FINAL REPORT



Final Report

Mars Society Desert Research Station

Project Greenhab

Greenhouse Completion and

Living Machine Installation for Wastewater Recycling

October 19, 2002

Prepared by:

David Blersch

Department of Biological Resources Engineering

1457 Animal Sciences/Ag. Engineering Building

University of Maryland

College Park, Maryland, USA

Email: dblersch@wam.umd.edu

TABLE OF CONTENTS

TABLE OF CONTENTS 1

1.0 objectives 2

2.0 project background 2

3.0 Scope of Work 5

4.0 System Overview 6

5.0 Report on Task Completion 7

6.0 Recommended Future Work Items 25

7.0 Long Term STrategies 28

8.0 Conclusions 30

9.0 References 30

Objectives

The overall objective of the installation work, pursuant to the mission of the Mars Society’s Greenhab project, was the construction of a system for wastewater management in support of field/simulation activities Mars Society’s Desert Research Station (MDRS). The Greenhab project is tasked with the exploration and development of technologies for life support appropriate for manned missions to Mars, and within that context favors development of biologically-based life support technologies whenever possible. The specific installation work described here represents what is considered by Greenhab task force members as the first stage in a long-term project of development of life support technologies: that of recycling wastewater from the MDRS habitat to various uses within the habitat using biologically-based technologies. This installation crew was tasked with installation of a biologically-based wastewater treatment system (WWTS) to recycle gray and black water from the habitat for reuse within the habitat toilet. Ancillary objectives included completion of the greenhouse intended to house the WWTS, installation of various plumbing and electrical subsystems to support the WWTS, and installation of sterilization equipment within the habitat to process water returning from the greenhouse-based WWTS for safe use within the habitat toilets.

project background

1. Project History

The Greenhab Project was established in the fall of 2001 to continue the efforts of the Mars Society’s Life Support Technical Task Force, which evaluated water management designs appropriate for the Mars Society’s Flashline Arctic Research Station the previous year (Blersch, et al. 2002). The Greenhab Project resulted from discussions held between Gary Fisher and Bruce Mackenzie from the Mars Society and capitalized on the previous efforts of the Technical task force in an effort to produce a viable life support research program within the Mars Society.

The Greenhab project took upon itself the responsibility for designing and building the MDRS greenhouse to fulfill its threefold purpose: first, to provide a wastewater recycling system at MDRS, reducing resupply requirements for the station; second, establish a research facility for humans-to-mars related life support; third, simulate the appearance of a cylindrical inflated structure as a visual and operational analog to a possible Mars base greenhouse. A prototype greenhouse segment was constructed in winter of 2001/2002 at the MDRS site. Soon after, a companion greenhouse segment was constructed at the University of Maryland’s Department of Biological Resources Engineering in College Park, Maryland, to serve as a design and prototyping testbed to support MDRS activities. It was soon realized that the segment erected at the MDRS would not withstand for long the continued battering by the seasonal winds in southeastern Utah. A new structural design was developed throughout the spring of 2002 and partially installed by a work crew in early August of 2002 (Fisher, 2002).

2.2 Technology Summary

The intended use of the Greenhab greenhouse is to experiment with different technologies related to life support in space. Long-term human space missions require a large amount of consumables—food, water, and air—and recycling as much as possible in a closed or semi-closed system it desirable for reducing the overall mass of the mission. Biologically-based life support, in the form a closed ecological life support system (CELSS), attempts to use as much as possible the power of biological organisms and the sun to accomplish the recycling of human gaseous, liquid, and solid wastes to useful products. CELSS concepts are based upon the ecological relationships that exist between organisms, recognizing that one organisms wastes are another organisms food source. For example, the oxygen produced when a plant photosynthesizes (converts sunlight and carbon dioxide), while a waste product to the plant, is essential for human respiration, the waste product of which (carbon dioxide) is reciprocally essential to the plant. A CELSS system seeks to recreate these natural ecological cycles found on Earth, but in miniature through the use of technological components.

An essential part of any CELSS system is the recycling of wastewater and its nutrient components to useful products. Two candidate technologies are currently being explored by the Greenhab project to treat and to some extent recycle wastewater at the MDRS. Both systems are preceded by various tanks in which microbes break down organic (carbon-based) wastes in the water stream coming from habitat sinks, showers, and toilets. These tanks might be aerobic (with oxygen) or anaerobic (no oxygen). In an anaerobic tank (which, in principle, is similar to a backyard septic tank), the microbial reactions that occur break down the organics more slowly but more completely, converting the organic compounds to gaseous carbon compounds such methane, a byproduct that can be recaptured for fuel or released to the atmosphere.

The anaerobic microbial digestion of organic wastes also releases nitrogen from the waste in the form of ammonia or nitrate. Normally, in standard household septage, this high-nitrogen water from the septic tank is disposed of in a leach field where the nitrogen eventually degrades microbially. However, in a closed system, it is desirable to recapture as much nitrogen as possible. Nitrogen in the form of ammonia or nitrate can be useful to various green plants and algae (for example, most fertilizers contain a mix of nitrate and ammonia); hence, the microbial tanks will be followed by a system to include green plants. Two systems are currently under consideration: the hydroponic polishing system (HPS) and a living machine concept.

The hydroponic polishing system, or HPS, is intended for biologically-based treatment of the wastewater for the removal of nitrogen and phosphorus compounds. The HPS is not a true hydroponic plant growth system, which usually employs a sterile nutrient fluid stream in which plants grow. Rather, the HPS concept is based upon overland flow systems, a common large-scale municipal wastewater treatment process in rural area in which nutrient-rich wastewater is allowed to flow over sloped land through a bed of plants. The main components of the Greenhab’s HPS include a sloped waterproof sheet underlying a bed of fibrous coir mat (made from coconut fibers), forming a substrate in which plants can root and grow. A drip irrigation system trickles the nutrient-rich water onto various locations on the bed, proving a moist environment around the plant roots. Nutrients are removed from the water by the plants themselves and by microorganisms that colonize the mats and the plant root zones. To compensate for the large area typically required for overland flow systems, water in the HPS system will be recirculated through the mats between 10 and 20 times per day to adequately treat the waste load coming from the habitats. The beds will be planted with salt- and drought-tolerant plants such as alfalfa and barley, the stems of which might also make a good amendment to a compost operation. Additionally, the large surface area of the HPS mats will provide a significant rate of water evaporation; recapturing this water vapor with a condenser can yield clean, pure water suitable for potable applications. A sketch of the Greenhab’s prototype HPS system is shown in the Figure 1 (Blersch, et al. 2002). While a prototype of the HPS was installed in the first MDRS greenhouse in March of 2002, the system proved susceptible to freezing and difficult to maintain: the system remains under development.

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Figure 1: Schematic drawing of the HPS system under development for the MDRS greenhouse.

Another possible candidate wastewater treatment system being investigated is a living machine, a series of bioreactor tanks comprising various different aquatic ecosystems. The philosophy of the living machine concept is based upon the inherent stability of ecosystems resulting from high species diversity, fundamentally different from the monoculture approach employed by the HPS. By including a large number of microbial, plant, and animal species in different combinations in different tanks, numerous and varied metabolic pathways are created for the conversion and uptake of nutrient wastes. The ecological complexity of the system provides a process redundancy that makes the entire system resilient to catastrophic failure. In addition, the mechanical components of a living machine can be quite simple—a viable living machine might be constructed with merely one pump, large-diameter plumbing, and a few tanks—thus making the mechanics of the system as resilient to catastrophic failure as the ecological components. Experience with other greenhouse-based living machines has shown that these systems might run adequately for weeks at a time with little or no maintenance, a characteristic

desirable for remote locations such as the MDRS. While living machines have been shown to adequately and efficiently treat wastewater to acceptable levels (Todd and Josephson, 1996), the addition of multiple life-support functions, such as atmospheric management and food production, will be eventually be explored within the Greenhab project. Prototyping of a living machine suitable for the MDRS was performed at the University of Maryland: a schematic of the prototype living machine built and studied at the University of Maryland is show in Figure 2 (Blersch, et al. 2002):

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Figure 2: Schematic drawing of the living machine prototyped at the University of Maryland.

3.0 Scope of Work

1. Tasks

Pursuant to the objectives and background outlined above, the work crew for this specific installation operation at the MDRS was tasked with the following work items:

• Install insulation, diamond plate, and pig flooring in greenhouse (Greenhab work order GH2002001.11);

• Install Greenhouse ends (Greenhab work order GH2002002.00);

• Replace Dryer/Compster Door (Greenhab work order SP2002001.00);

• Install 110 gallon Rentention Tank and Sump pump (Greenhab work order SP2002002.00);

• PowerPod Move and PV Panel Installation (Greenhab work order PS2002001.00);

• Install Living Machine for processing of septic overflow water (no specific work order);

• Install sterilization system for processing of Living Machine water (no specific work order);

• Install improved HPS developed for Adler exhibit (no specific work order).

2. Dates of Operation

Installation operations were conducted from Monday, October 7, through Saturday, October 16, 2002, at the Mars Society’s MDRS near Hanksville, Utah.

3. Work Crew Personnel

Personnel involved in the installation operations were as follows:

David Blersch

Dennis Creamer

Dr. Patrick Kangas

Greg Mungas

Frank Schubert (Monday and Tuesday only)

Jeff Zerr

Mr. Creamer deserves special recognition for driving a delivery van from Chicago to the MDRS site to transport parts from the greenhouse constructed for the Mars Society’s Adler Planetarium exhibit the previous summer.

System Overview

The system intended to be installed in this operation is a functional wastewater treatment and partial recycling system for the MDRS. A system overview is given in Figure 3. Wastewater from the habitat sinks, showers, and a toilet to be installed drains via gravity to a 100-gallon septic tank in the ground (installed on a previous construction trip). Overflow water from the septic tank, rather than flow to the partial leach field (constructed on site in August), is routed to the 110-gallon holding tank also in the ground. When this tank fills to a certain level, a float-switch controlled AC pump pumps water from the 110-gallon tank into the first tank of the living machine in the greenhouse. The living machine consists of five separate tanks housing various ecosystems: Tank #1 is a 20-gallon trickling filter, in which an attached microbial community processes organic and nutrient wastes; and Tank numbers 2 through 5, 55-gallon tanks in which complex aquatic communities of microorganisms, submerged and emergent plants, and invertebrates continue to process organics and nutrients in the wastewater. A small DC pump, powered with a solar panel, continuously recycles water from Tank #5 back to Tank #1, lengthening the effective retention time and keeping the biology alive when left unattended. A pump in Tank #5 returns water through a filter to the 20-gallon toilet supply tank in the habitat and is controlled either by manual or float switch. A separate pump continuously pumps water in the toilet supply tank through a UV filtration unit for sterilization. Once the toilet is installed, water may be drawn from the toilet supply tank on demand for flush purposes. Also, an overflow standpipe in Tank #5 in the living machine sends excess water to the leach field should the capacity of the living machine tanks be overrun.

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Figure 3: Schematic drawing of the wastewater treatment system installed at the Mars Society's MDRS.

Report on Task Completion

Summaries of the various tasks addressed and completed in this installation operation, as listed in Section 3.1 of this report, are outlined below.

1. TASK: Install insulation, diamond plate, and pig flooring in greenhouse.

Greenhab Work Order GH2002001.11

Task origination: Tuesday, October 8

Task completion: Tuesday, October 8.

The foam board was found under the habitat, as left from the construction trip in August. Its condition was generally good. Four pieces were used to cover the floor of the greenhouse in between the lengths of 2x4 comprising the existing floor substructure. The foam board was cut to fit in between the 2x4s and around the protruding 4” conduit access ports (Figure 4).

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Figure 4: Floor insulation installed in the Greenhab greenhouse segment.

Diamond plate sheets and scraps were found on a large pallet in the junk pile near the MDRS site. There were approximately 5 or 6 full sheets (4x8 ft) of diamond plate; three sheets lain side by side were enough for covering the entire 8x12 ft floor of the greenhouse. Rectangular holes were cut in the diamond plate to fit over 4” conduit access ports (after repeated trial and error, it was determined that the diamond plate may be easily cut with a Sawzall with a fine-toothed blade; a hole saw was not tried under the assumption that it would not be able to cut the diamond plate). The floor was installed (see Figure 5) and held in place using 2” deck screws through holed previously drilled in the diamondplate (the 1-1/2” self tapping stainless screws were not used in order to conserve them for the greenhouse walls). The screws were installed mostly in the corners of the diamond plate with some on the sides and should be relatively easy to access should it be necessary.

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Figure 5: Floor diamondplate installed in the Greenhab greenhouse segment.

All members of the work crew contributed to this task. Mr. Schubert and Mr. Mungas deserve special commendation for transporting the diamondplate sheets to Hanksville to be cut.

2. TASK: Install Greenhouse ends (Greenhab work order GH2002002.00);

Greenhab Work Order GH2002002.00

Task origination: Tuesday, October 8

Task completion: Saturday, October 12

Installation of the greenhouse ends, delivered from the Adler exhibit greenhouse in Chicago, was the most onerous task undertaken this trip. It was realized early on that a significant amount of custom fitting of the ends would have to be performed to fit the Adler ends to the existing greenhouse; it is this custom fitting which made the task span the entire time the construction crew was at the MDRS site.

One of the difficulties with installing the ends was the fact that the greenhouse structure had possibly sagged in the few months it has been sitting unattended in the Utah desert; consequently, the cross-sectional shape was more elliptical than circular, resulting in vertical dimensions that were shorter than expected and horizontal dimensions longer than expected. To counter this, U-brackets were crafted out of spare strapping material and installed at four points around each end hoop of the greenhouse. Next, ratchet straps were installed connecting opposite U-brackets: when tightened, these ratchet straps formed an “X” across the end hoop of the greenhouse. Incremental tightening of these straps allowed adjustment of the shape of the hoop back to circular. Another difficulty encountered was the interference of the corrugated polycarbonate and twinwall sheets that formed the inner and outer curved skin of the greenhouse. Both the corrugated polycarbonate and twinwall sheets extended beyond the outer hoops of the greenhouse structure; these were trimmed with a razor knife and/or the Sawzall so the ends were flush with the steel hoops. Additionally, where the inner twinwall sheets interfered with installation of the U-clamps for mounting the box beam structure, a hole was cut in the twinwall with a razor knife to allow passage of the U-clamp.

Once these difficulties were recognized and mitigated, the general procedure for attaching the walls was as follows, starting first with the south wall and concluding with the north wall: first, the vertical box beams extending down from the top of the greenhouse hoop structure were attached, centered using a plumb bob. Next, the doorframe was installed under these beams and attached, cut to length as necessary forming a butt joint with the diamondplate floor (Figure 6). Then the box beam structures for either side of the door frame were assembled and fit into place, adjusting the shape of the hoop cross section as necessary; shims or spare brackets were constructed and inserted as necessary to make up for gaps between connection points. Box beams were attached using the hardware available from the Adler exhibit greenhouse, mostly steel angles and self tapping screws, and U-clamps and ¼” bolts. Vent frames were then installed on top of the door frames using deck screws. Once the box beams were attached in place, the triple wall sheets from the Adler were fit into place, cut as necessary (generally, only the bottom sheets required cutting of about 8 to 12” from their bottom edges, equivalent to the amount the MDRS greenhouse is buried), and tacked up with 2” self-tapping screws to the hoop structure. The 1” aluminum flashing was then installed covering the gaps between the triple-wall sheets, attached to the structure using 1-1/2” self-tapping screws and 1” gasket washers. Generally, the panels did not exactly align with the previously tapped screw holes from the Adler construction, so new holes were made as necessary.

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Figure 6: Door frame and box beam structure installed on the south wall.

With the triple wall in place, the doors, black vents, and fan assemblies were then installed. Note that the black vents were installed with the removable rubber flaps facing out of the greenhouse; were they installed facing inwards, the 2x4 vent frames would have blocked removal of these flaps. The DC fan was installed on the south wall with a black vent above it. This fan is powered by the 17V PV panel installed above the south door, and is controlled by an on-off switch inside the greenhouse above the south door. The AC fan was installed on the north wall, with a black vent above it. Also, note that the doors were hung with approximately a ½” gap underneath, resulting from careful adjustment of the doorframes prior to installation. After this, the end-to-end bracing was assembled, cut to fit, and installed above the doorways (note that the X-braces to stabilize these were NOT installed, and should probably be installed by the next work crew). For structural stability, ratchet straps were installed in an X-pattern along the length of the length of the greenhouse on the east and west sides, joining the upper U-clamps on the north and south ends with the lower U-clamps on the opposite walls. A ratchet strap was also installed between the upper U-clamps on each end wall, securing the structure from inside. Finally, two tiedowns were installed, one on each end from the top of the end hoop to a stake in the ground. The final greenhouse installation is shown in Figure 7.

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Figure 7: Final greenhouse installation with ends installed and ratchet strap tiedowns.

Cotemporaneous with the installation of the ends, the 12 foot twin wall sheets were installed in the interior of the greenhouse with the Suntuff 1” self-tapping screws, forming a double membrane for the greenhouse skin. This work was undertaken and completed by Thursday, October 10 so the interior tanks and plumbing might be installed.

All members of the work crew contributed to this task at various times during the week. Mr. Zerr deserves special commendation for overseeing the installation and custom fitting of the box beam structure. Mr. Creamer deserves special commendation for installing the DC fan, PV panel, wiring and switch.

3. TASK: Replace Dryer/Compster Door

Greenhab work order SP2002001.00

Task origination: Tuesday, October 8

Task completion: Tuesday, October 8

The door to the composter was replaced per the work order with little or no difficulty (Figure 8). The door height was measured to be 3 feet, 7 ½ inches. Also, it was determined that between 7 and 8 feet of additional ¾” hose would be required to move the composter to the far side of the manual hand pump. Additionally, the blue tarp was removed from the bottom of the composter, and the hoe was cleaned, painted, and left inside the hab airlock.

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Figure 8: Composter with repaired door.

It is interesting to note that the old composter door was found during the week approximately ½ mile to the north of the MDRS location, partially buried by silt. The old door was retrieved and placed next to the composter weighted down by a rock.

4. TASK: Install 110 gallon Rentention Tank and Sump pump

Greenhab work order SP2002002.00

Task origination: Tuesday, October 8

Task completion: Saturday, October 12

Digging of the hole for the 110-gallon tank was undertaken on Tuesday and Wednesday of the work week and focused upon expanding the hole previously dug on the north-west corner of the greenhouse. Digging was accomplished using a pick axe bought at Home Depot, and proceeded until the hole was large enough all but the top of the 110-gallon tank would be buried (Figure 9).

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Figure 9: Hole dug for burying of 110-gallon tank.

Inspection of the 110-gallon tank showed that, in addition to the 10” access port on top, the tank had two open threaded bulkhead fittings on the bottom, one 1-1/2” in diameter and one 1” in diameter. A threaded plug was found for the 1” bulkhead fitting, but none could be found for the 1-1/2” fitting. Rather, this one was first filled with polyurethane foam sealant (“Great Stuff” from Home Depot). When this was dry, the remaining space in the fitting was filled with silicone sealant, and a small flat circle of plastic was pressed over this and sealed in place to complete the seal. It took until Friday for all this sealant to adequately dry, which prevented earlier installation of the tank. It is possible that the 1-1/2” fitting will leak slightly, but it is expected to not be enough to cause a problem.

Once the tank was installed in place, two bulkhead fittings were installed in the top of the tank: a 1-1/2” threaded fitting on the top of the tank nearest the greenhouse, and a 1” threaded fitting on the side of the tank close to the top on the end nearest the hab and septic tank (prior to installing the 1” fitting, the drop along the 15 ft. distance from the septic tank outlet to the top of the 110-gallon tank was measured, with string and level, to be no more than 6”; to provide extra head for septic tank drainage, it was decided to mount the 1” fitting on the side of the tank rather than the top).

With the bulkhead fittings in place, the Flotec pump was placed in the tank on top of a cinder block near the greenhouse-end of the tank, effectively raising it 8” off the bottom of the tank. This placed the pump’s float switch such that it would turn the pump on when water in the tank reached approximately 90 gallons. The outlet of the Flotec pump (a 1-1/4” FPT port) was plumbed with a 1-1/4” MPT to ¾” hose barb, a short (6”) length of ¾” ID hose, and the blue spring check valve (3/4” FPT ports with ¾” MPT to hose barb adapters inserted). As an air outlet, two 1/16” holes were drilled in one of the hose barb adapters between the pump and the check valve. The 20 foot length of black ¾” garden hose was then attached to the hose fitting on the outlet of the check valve. This hose and the electrical plugs for the pump and float valve were run through the 1-1/2” bulkhead fitting closest to the greenhouse; extra space in the fitting was then filled with a wad of fiberglass insulation, which may be removed if necessary for access. This hose was run into the greenhouse via the nearest sub-floor 4” conduit, and attached to a hose barb fitting inserted into a ¾” bulkhead fitting in Tank #1 (Trickling filter) of the greenhouse.

Additionally, the ¾” drain hose from the septic tank was unburied. Water use by the work crew during the week showed that this hose was likely plugged, as water would seep from under the lid of the septic tank following water use. Inspection of the drain hose after unburying revealed that approximately the last 6” was full of compressed wet silt, completely stopping any flow. The last 12” of this hose was cut off with a hose cutter, and water began to flow freely. The end of this hose was loosely inserted into the 1” bulkhead fitting on the hab side of the 110-gallon tank, and a wad of fiberglass insulation was inserted to take up extra space. See Figure 10 for final tank installation.

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Figure 10: Final installation configuration of 110-gallon holding tank.

Note that the hoses and wires to and from this tank were left unburied at the end of the work operation. This is to allow any future inspections and changes that might be instituted prior to the simulation operations this season. When buried in the future, the hoses might be run through more 4” conduit; three 10’ lengths of conduit, plus numerous fittings, are stored under the hab near the rear airlock.

5. TASK: PowerPod Move and PV Panel Installation

Greenhab work order PS2002001.00

Task origination: Tuesday, October 8

Task completion: Saturday, October 12

The Powerpod was moved from its previous location to a new location near the southeast corner of the greenhouse, near the existing flagpole (see Figure 7 in Section 5.2). The solar panels were found in the habitat in good condition; these were mounted on the Powerpod pole and electrical wires were hooked up. Once the location of the Powerpod was determined adequate, the Powerpod was anchored using three duckbill anchors and wire rope assemblies; the wire ropes were attached to the eyebolts on the neck of the Powerpod using the steel/rubber straps from the old greenhouse and ¼” bolts and nuts. The duckbill anchors were driven into the ground approximately 12” (possibly not enough for very high winds).

Once the Powerpod was in place, the all-weather cable was connected and run into the greenhouse through the southwest sub-floor 4” conduit opening. This wire was run up to the DC power distribution box, which had been found, cleaned, and mounted inside the south wall on the doorframe. The wire was connected to the main 20A breaker in the box. One of the 12V DC pumps was run through one of the 10A circuit breakers, and the Diehl timer, mounted directly below the distribution box, received 12V DC power directly through no breaker. The timer was installed to control the DC pump (intended for the living machine internal recycle from Tank #5 to Tank #1), and left in the “ON” condition using the manual override switch on the timer control. A circuit schematic is given in Figure 11.

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Figure 11: Circuit diagram of the Powerpod and DC distribution box.

6. TASK: Install Living Machine for processing of septic overflow water

No specific work order

Task origination: Thursday, October 10

Task completion: Saturday, October 12

Installation of the living machine did not commence until the twin wall sheets were installed on the interior of the greenhouse, dependent upon a certain amount of completion of the greenhouse ends. Once commenced, living machine construction was performed contemporaneously with other tasks.

The living machine consists of five separate tanks, each housing a different ecosystem. The layout follows the general schematic shown in Figures 12 and 13.

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Figure 12: Plan view of the installed living machine.

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Figure 13: Elevation view of the installed living machine.

Water is pumped into the system from the 110-gallon tank on the north end of the greenhouse; this pump is controlled by a float switch and is thus activated when enough wastewater is discharged from the hab. This water is pumped into Tank 1, the trickling filter; this tank is mounted high (approx. 60”) to provide gravity potential head to allow the subsequent tanks to be fed via gravity feed. Subsequent tanks are installed at successively lower heights: Tank 2 is 16” off the greenhouse floor (two cinder blocks high), Tank 3 is 8” off the floor (one cinder block high), and Tanks 4 and 5 are sitting on the floor. With the exception of Tank 1, the construction of each of the tanks is similar: a 1-1/2” FPT bulkhead fitting is inserted 4” from the bottom of the tank; a 1-1/2” standpipe on the inside of the tank controls the level of water in the tank (the standpipe may be revolved about it’s horizontal member to adjust the water level within a range of 2”); and 1-1/2” pipe is installed (with the exception of Tank #5) on the exterior of the bulkhead fitting to deliver water to the top of the next lower tank. The entire system of tanks as installed is shown in Figures 14, 15, and 16. Following these, individual tank descriptions are given.

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Figure 14: Tanks 2 through 5 of the living machine.

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Figure 15: Tank 1 and spare water tank of the living machine.

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Figure 16: Entire living machine installed in the west side of the greenhouse.

Tank Descriptions:

|Tank 1: |Trickling filter |

|Purpose: |Aerobic metabolism of organics & nutrients |

|Dimensions: |14x14x24” (square) |

|Capacity: |20 gallons |

|Material: |Blue polyethylene |

|Elevation: |Approx. 60” |

|Inlets: |1” bulkhead inlet w/ ¾” hose barb |

| |½” line from recycle pump |

|Outlets: |1-1/2” bulkhead w/PVC pipe |

|Internal: |1 cu. Foot of bioballs |

|Biology: |Attached growth microbial community |

|Tank 2: |Aquatic Tank |

|Purpose: |Uptake of organics & nutrients |

|Dimensions: |22” diameter x 36” tall |

|Capacity: |55 gallons |

|Material: |Translucent polyethylene |

|Elevation: |Approx. 16” |

|Inlets: |1-1/2” gravity feed from Tank 1 |

|Outlets: |1-1/2” bulkhead w/PVC pipe |

|Internal: |1-1/2” standpipe, 30” long |

|Biology: |Water hyacinth (from nursery in Grand Junction, CO) |

| |Polygonum sp. (from UMD) |

| |Elodea sp. (submerged, from UMD) |

| |Aquatic invertebrates fr. Bull Cr., Henry Mts. |

|Tank 3: |Aquatic Tank |

|Purpose: |Uptake of organics & nutrients |

|Dimensions: |24” diameter x 36” tall |

|Capacity: |55 gallons |

|Material: |Black polyethylene |

|Elevation: |Approx. 8” |

|Inlets: |1-1/2” gravity feed from Tank 2 |

|Outlets: |1-1/2” bulkhead w/PVC pipe |

|Internal: |1-1/2” standpipe, 30” long |

|Biology: |Water Lettuce (from nursery in Grand Junction, CO) |

| |Ludwigia sp. (from UMD) |

| |Aquatic invertebrates from a drainage ditch in Green River |

|Tank 4: |Aquatic Tank |

|Purpose: |Uptake of organics & nutrients |

|Dimensions: |22” diameter x 36” tall |

|Capacity: |55 gallons |

|Material: |Translucent polyethylene |

|Elevation: |None |

|Inlets: |1-1/2” gravity feed from Tank 3 |

|Outlets: |1-1/2” bulkhead w/PVC pipe |

|Internal: |1-1/2” standpipe, 30” long |

|Biology: |Water hyacinth (from UMD) |

| |Azola sp. (from nursery in Grand Junction, CO) |

| |Pennywort (from nursery in Grand Junction, CO) |

| |Green algae from Crescent Creek |

| |Blue-green algae from Rt. 24 roadside ditch |

|Tank 5: |Aquatic Tank |

|Purpose: |Uptake of organics & nutrients |

|Dimensions: |30” diameter x 30” tall |

|Capacity: |64 gallons |

|Material: |Black polyethylene |

|Elevation: |None |

|Inlets: |1-1/2” gravity feed from Tank 3 |

|Outlets: |1-1/2” bulkhead w/ 3/4” barb adapter |

|Internal: |1-1/2” standpipe, 24” long |

|Biology: |Terrestrial plants in pots on floating rack: |

| |Spider plants |

| |Philodendron sp. |

| |Duckweed (from UMD pond) |

|Tank 6: |Spare Water Tank |

|Purpose: |Reservoir of spare nonpotable water for emergencies; structural |

| |component for Tank 1 stand |

|Dimensions: |24” diameter x 36” tall |

|Capacity: |55 gallons |

|Material: |Blue polyethylene |

|Elevation: |18” |

|Inlets: |2” bung port (sealed) |

|Outlets: |¾” stopcock |

|Internal: |None |

|Biology: |None |

Note that each of the standpipes has a removable 12” cover that allows water to flow but prevents floating plants from entering the standpipe. All plants were inserted into the tanks as soon as the end walls were complete; tanks were filled with water delivered to the hab, and Miracle Grow was mixed into the water stream to encourage rapid plant growth and establishment. Aquatic heaters were installed on Tanks 2 and 4; these heaters are AC and could not run off the Powerpod (this was attempted, but the Powerpod circuit was immediately overloaded). Note that there is currently no heat in the greenhouse; it is uncertain whether or not the plants will survive over the next few weeks without tending. Should they senesce or die, new plants might be shipped out from various suppliers.

Tank 5 of the living machine is special in the sequence, as is houses additional pumps and provides the system overflow. The DC pump connected to the Powerpod is dangling in Tank 5 approximately halfway down the water column; this returns water back to Tank 1 via a ½” vinyl hose wrapped in hose insulation at a flow rate of approximately 4 gpm. Also, the Pondmaster 1800 pump is in the bottom of this tank. This feeds the dual filter preceding the toilet supply tank in the hab via 50’ of black ¾” garden hose, which is run through the 4” conduit port in the floor of the greenhouse and continues through 4” conduit run under the hab. Finally, Tank 5 has the system overflow standpipe. Should water be pumped into the system in excess of its capacity, water will overflow into this standpipe. The outlet of the standpipe is currently adapted to a ¾” hose barb, followed by a short length of vinyl hose connected via adapter to the green garden hose that extends to the drainfield. Testing of the overflow standpipe first showed that the end of the drain garden hose was plugged, as no water drained at all; this was solved by cutting the hose where it entered the drainfield. Subsequent testing showed that, even with a completely unblocked drain hose, water could not flow through the ¾” hose fast enough to prevent Tank 5 from overflowing (when water is being pumped into the system)—this is a potential problem situation that should be resolved in future work operations.

Tank 1 of the living machine is also special in the sequence, as it provides an environment for a microbial community that might be different than elsewhere in the living machine. This tank is fed continuously by the ½” line from the recycle pump in Tank 5. This line terminates in a manifold that distributes water flow evenly over the cross section of the tank; this manifold merely sits on top of the bioballs in Tank 1. Should it be necessary, the flow rate for this recycle may be controlled by a gate valve installed on the manifold inlet. This tank also receives water from the float-switch-controlled Flotec pump in the 110-gallon tank. This water enters the tank through the 1” manifold installed near the top of the tank, to which a 3 ft. length of hose is attached on the inside via barb adapter to funnel water near the bottom of the tank to prevent oversplashing.

In addition to the hose from Pondmaster pump, the 4” conduit installed between the workbench area of the hab and the greenhouse contains the following: two 12-gage stranded wires (one white, one black) suitable for AC or DC power; one all-weather AC cable; a length of nylon cord (for pulling through other lines in the future); and the 30 foot pipe heater (plug end in the habitat by the work area).

7. TASK: Install sterilization system for processing of Living Machine water

No specific work order

Task origination: Thursday, October 10

Task completion: Saturday, October 12

The system for sterilization of the water was installed according to instructions and guidance pictures given via email. The black hose from the pump in Tank 5 is connected to the inlet of the dual filter, installed on the wall above the work area (Figure 17). A short length of ¾” hose connects the outlet of this filter to a 1” bulkhead fitting installed near the top of the toilet supply tank (same dimensions as Tank 1 of the living machine—see Section 5.6), installed on top of the workbench (Figure 17). A separate loop is installed in this tank to pump water in this tank through the UV filter, installed under the workbench (Figure 18). These tank connections are 1” bulkhead fittings as well. Another 1” bulkhead fitting is installed near the bottom of this tank, to which a garden hose is attached that is run across the workbench into the bathroom, awaiting toilet hookup. Finally, a small ¼” bulkhead fitting was installed on the side, to which a ¼” clear vinyl tube was connected for visual inspection of the water level in the tank.

[pic]

Figure 17: Toilet supply tank and dual filter installed in the work area in the hab.

[pic]

Figure 18: UV filter installed under the workbench in the work area.

Testing of the system met with mixed success. The Pondmaster pump in Tank 5 of the living machine adequately provides water through the dual filter and into the toilet tank at a flow rate of approximately 3 to 5 gpm. Testing of the UV filter revealed that the pump supplied with the assembly was damaged: the female threaded outlet port was split and leaking seriously. A similar pump, on hand from the Adler equipment, was substituted and tested; this pump leaked through its housing (possibly because this one was designed to be submersible). The original pump might be repaired by replacing the faceplate that covers the impeller assembly and houses both the inlet and outlet ports; however, it is recommended that the pump be entirely replaced.

8. TASK: Install improved HPS developed for Adler exhibit

No specific work order

Task origination: N/A

Task completion: N/A

This task was not performed due to time constraints. Most equipment and materials for this mechanism were stored under the habitat next to the remains of the old greenhouse. The barrel used for this mechanism is stored in the greenhouse on the east side. The pump for this mechanism is stored in the work area in the hab.

Recommended Future Work Items

Pursuant to the installation summary detailed in section 5, a number of work items were left incomplete on this operation and should be addressed as soon as possible by future work crews. These may be summarized as follows according to subsystem:

Greenhouse:

• The cross structure on the end-to-end framing was not installed. This should be installed as soon as possible to secure the structure of the greenhouse. Parts for this task are stored in the greenhouse on the east side.

• Ratchet straps should be installed in the greenhouse from the ends of the end-to-end framing to the opposite corners of the greenhouse (Figure 19). Without this reinforcement, the greenhouse ends vibrate together under wind load, which, over time, may dislodge some of the screws holding the end assemblies together. There is at least one unused ratchet strap stored in the greenhouse: four would be necessary for proper securing.

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Figure 19: Suggested arrangement for ratchet straps to secure greenhouse ends.

• The doors were not sealed with weather strip; this should be done before colder weather strikes. Weather stripping is stored in the greenhouse.

• The wood corner pieces were not installed on the doors; again, this should be done before colder weather strikes. The corner pieces are stored in a Ziploc bag hanging on the inside of the north door.

• The greenhouse should be sealed with caulk, particularly between the ends and hoop structure. The caulk is stored in the red-topped storage bin in the greenhouse.

• While the latch was installed on the south greenhouse door, there was no latch hardware for the north door. This should be installed to guard against wind damage (currently, the door is tied from the inside with a bungee cord). Additionally, the doors are difficult to close from the inside; handles should be sent there and installed on the inside of both doors.

• Only two tiedowns were installed: one on each end. It may be desired to install tiedowns on the sides of the greenhouse as well.

• AC power needs to be installed in the greenhouse. The AC wire is run from the hab to the greenhouse; this needs to be hooked up to run the AC fan, the Flotec pump in the 110-gallon tank, the Pondmaster pump in Tank 5 of the living machine, and the water heaters in Tanks 2 and 4 of the living machine.

Composter:

• To replace the blue tarp, an aluminum chute might be fabricated and installed below the composter.

110-gallon Holding Tank:

• The hoses from the septic tank to the holding tank, and from the pump in the holding tank to the living machine were not buried in the 4” conduit as intended. The 4” conduit should be installed and buried. The conduit and fittings are located under the hab near the rear airlock.

• The bulkhead fittings in the top of the holding tank need to be sealed better, possibly with putty or GreatStuff. Following this, the tank should be buried.

Powerpod:

• The duckbill anchors may not be buried deep enough to withstand high winds. The anchors should be checked and reseat as necessary.

• Both voltmeters available at the hab were not operational, which caused difficulty in troubleshooting the Powerpod and circuitry. Spare 9V batteries should be brought to power the small yellow voltmeter, and the larger gray voltmeter should be sent for repair and calibration.

Living Machine:

• The spare water barrel in the greenhouse should be labeled “NON POTABLE” as soon as possible. This barrel had been used in its past to store an unknown substance, and while it had been washed as well as possible, this water should be not used for drinking. It should be safe to use this water for toilet flushing following discharge into the living machine first. Over the long term, this barrel should probably be replaced with a clean, new barrel with a solid (non-removable) lid.

• As soon as AC power is installed in the greenhouse, the aquarium heaters in Tanks 2 and 4 should be turned on to their lowest setting (20 degrees C) in order to keep the plants alive.

• There were not enough bioballs to fill Tank 1 (trickling filter). A quantity of 2” biobarrels will be shipped from University of Maryland in the coming weeks to the Whispering Sands Motel. These should be dumped into the trickling filter under the recycle manifold as soon as received.

• If left unattended, evaporation will eventually lower the water level in Tank 5 below the recycle pump, possibly harming the biology. One of the spare 12V DC pumps should be installed in the 110-gallon tank, powered by hooking it up to one of the two spare 10A circuit breakers in the Powerpod’s DC junction box. This pump should be controlled by a float switch installed above the recycle pump in Tank 5 of the living machine to keep the water level at some minimum. There are three spare DC pumps in the large blue bin in the greenhouse.

• The hand pump was not installed in Tank 5 of the living machine, since the HPS was not installed either. This may be installed when convenient. Two pumps are on site, one of which was packaged at University of Maryland with the mounting hardware. These pumps are stored in the greenhouse.

• As a long-term project, a solar water heater might be constructed out of ¼” copper pipe painted black and assembled to fit in spare spaces on the inside of the north greenhouse wall. This might be supplies with water from the living machine by one of the DC pumps connected to the PV panel that currently powers the DC fan. In this way, water is sent through the black pipes only when sunlight is incident on the greenhouse itself, passively warming the living machine water.

Toilet Supply:

• The toilet must still be installed. It is staged in the hab near the bathroom.

• The pump for the UV filter assembly must be repaired or replaced. It may be possible to repair it by replacing merely the faceplate that covers the impeller mechanism and contains the inlet and outlet ports.

• The control switch, either manual or float, must be installed to control the Pondmaster pump in Tank 5 of the living machine.

General:

• The ¾” drain hose currently attached to the overflow standpipe of Tank 5 of the Living Machine is likely too small for adequate flow capacity; i.e., the Flotec pump, when activated, supplies water to the system faster than the ¾” line can take it away, should an overflow condition be reached. This small-diameter line has repeatedly proven problematic, as they become easily plugged with silt and thus useless when the end is buried in the drainfield. It is recommended that this ¾” hose be replaced with a larger hose (1”) or hard pipe (1” or larger) to provide enough overflow capacity into the drainfield.

• The 4” conduit that runs under the hab to the greenhouse is only partially buried. Attention should be given to burying or insulating this conduit before inclement or cold weather.

Long Term STrategies

A number of ideas were developed during the most recent installation operation. A few of them are summarized here for consideration as long-term strategies for improving the system.

• While the curved portion of the greenhouse skin is double-walled, the ends are not. They might easily be made double by installing the twin wall on the inside of the box beams. This would help to insulate the greenhouse further. Currently, there is probably not enough double wall on site to perform this operation.

• With the living machine now installed, consideration should be given to development of a viable remote monitoring and control system. At the very least, sensors for water temperature, water flow, water level, and dissolved oxygen should be installed with a simple data acquisition system. This may be built upon in the future for more active control of water supply and control. For example, the water available to the habitat might be controlled not by availability of water, but by availability of treatment or storage capacity in the waste treatment system. This is a fundamentally different water management pattern than is conventionally accepted, and may prove interesting for study (this idea was suggested by Greg Mungas).

• The water cycle for the MDRS is very tight due in part to significantly undersized tanks. While the 110-gallon tank and living machine do indeed provide some extra capacity, the system is likely undersized for the amount of usage it will be getting (consider that a standard 4-person home is designed with a 1000-gallon septic tank in the ground, whereas the MDRS, hosting 6 people, has only 210 gallons in the ground). Serious consideration should be given to increasing the septic tank volume in the ground.

• A water quality monitoring program should be designed and instituted to evaluate the performance of the system as a step in its iterative design. Ideally, qualities such as total suspended solids, chemical or biological oxygen demand, nitrogen content (ammonia and nitrate), conductivity (giving an indication of salt concentration), and fecal coliform should be monitored regularly by regularly paid staff (probably not simulation crew members, as consistency in measurements would be paramount). However, this causes a problem of hazardous chemical storage and disposal, as many of these tests require hazardous reagents. Thought should be given as to how best to design a viable monitoring program.

• While the living machine should prove successful in treating all wastewater streams from the habitat, there still remains the fundamental problem of surplus water coming into the system. This results from the fact that only toilet water will be recycled, but considerable volume of wash water will be input every day from clean water storage. This invariably will result in some water being discharged to the drain field; granted, this water will be clean from its time in the living machine (an improvement over past simulation operations), but it may generally be considered a waste of water. It would be much more desirable to recycle water as much as possible, for wash applications and eventually for potable uses. However, the extant health risks posed by recycling black water for nearly any use is troublesome and the technology remains generally unproven. Two proposals are possible. First, construct some system of raceways in the greenhouse to provide a large surface area for evaporation, disposing of as much water as possible using ambient sunlight. This may take a lot of engineering and trial and error to produce a system that can evaporate upwards of 50 gallons of water a day. Paired with an adequate system to condense water from humid air in the greenhouse, this system may have the benefits of producing a measurable quantity of pure clean water.

As a second proposal, given the conditions and the tankage now installed at the MDRS, the best proposition for recycling water to wash sources is to separate wastewater draining from the hab into black and gray water streams. Gray water (sink and showers) might be sent directly to the 110-gallon holding tank (now used as a primary septic tank) and treated through the existing living machine for eventual recycle back to toilets and wash sources (following more stringent sterilization unit processes not yet installed at MDRS). Black water might be sent to the 100-gallon cone-bottom tank, and effluent from this tank might be treated in another living machine on the opposite side of the greenhouse from the exiting one; the treated water from this living machine might then be sent to the drainfield. This proposal has numerous advantages from a flow standpoint: the high flow stream (wash water) is recycled more readily, whereas the low flow stream (black water) is retained in its treatment train longer and is thus treated more thoroughly for safe discharge. This option must be considered a medium to long-term research project, as care must be given to incorporate adequate filtration and sterilization to avoid health risks. (Note that this idea was first proposed by Frank Schubert and was subsequently developed further by all on the installation team).

Conclusions

The Greenhab greenhouse is now a fully, albeit marginally, functional wastewater recycling system at the MDRS. Provided the structural and thermal integrity of the greenhouse is maintained, the biology of the living machine should continue to exhibit adequate performance in the treating of the habitat wastewater. Significant improvements can be made, some of which have been suggested here. Considering the success of the most recent installation, the long term prospects for the development of a viable wastewater treatment and recycling system are good, attaining the first milestone in an even more ambitious program in life support development.

References

Blersch, D.M., Biermann, E., Calahan, D., Ives-Halperin, J., Jacobson, M., Kangas, P. 2002. A proposed design for wastewater treatment and recycling at the Flashline Mars Arctic Research Station utilizing living machine technology. Presented at the Third Annual Convention of the Mars Society, August, 2000. Reprinted in: On to Mars: Colonizing a New World. R. Zubrin and F. Crossman, eds. Apogee Books, Burlingon, Ontario, Canada.

Blersch, D.M., Calahan, D., Kangas, P. 2002. Project Greenhab at the University of Maryland: A University Platform for Life Support Engineering and Education. Presentation given at the Mars Society’s Fifth International Convention, August 8-11, 2002, University of Colorado at Boulder.

Fisher, G.C. 2002. Project Greenhab—The Origin, Efforts, and Future. Presentation given at the Mars Society’s Fifth International Convention, August 8-11, 2002, University of Colorado at Boulder.

Todd, J. and B. Josephson. 1996. The design on living technologies for waste treatment. Ecological Engineering 6: 109-136.

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