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CCAT greenhouse water reclamation

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Abstract[edit]

Humboldt State University's Campus Center for Appropriate Technology (CCAT) is looking to further increase the sustainability of its practices. CCAT recognized that the water used on plants in its greenhouse was not being utilized to its fullest potential, especially when watering plants on the gardening tables. The water would run off to the ground and sometimes damage the plants that are grown under the tables. A water reclamation system was created to recycle the runoff water and protect the plants that grow below these tables.

Background[edit]

The Four Peppers: Harry Jones, Lauren Virzi, Mario Kaluhiokalani, and Amanda Madden are four spicy Humboldt State University students and creators of the greenhouse water reclamation system at CCAT. CCAT recognized the possibility of recycling water from the gardening tables within its greenhouse by installing a reclamation system. A need to re-purpose runoff water from the greenhouse's plants instead of letting it seep into the ground was made clear by CCAT, so we set out to put this water back to use! Through the use of local knowledge and materials that are available at CCAT and in the surrounding community we were able to do just that. Our project lasted a duration of 13 weeks spanning over the Spring 2019 academic semester.

Problem Statement[edit]

The objective of this project is to implement a water reclamation system that recycles water used to hydrate plants in the greenhouse as an effort to increase sustainable practices at CCAT. There is also an issue of seedling degradation due to the high velocity of water droplets that fall down to the seedling beds from the plants above. Our job is to find a way to divert and catch that water to protect the integrity of the seedlings.

Criteria[edit]

The following Criteria are used to assess the success of this project. These criteria were chosen based on suggestions from the project coordinator and input from the students who worked on this reclamation system. The scale (1-10) represents the relative importance of meeting the constraint listed by each criteria with 1 being the least important and 10 being the most important.

Criteria Constraints Weight
(1-10)
Efficiency The reclamation system will retain 90% or more of all run-off water from watered plants
5
Maintenance Must be easy to clean the tubing and remove debris, no more than 2 hours maintenance per month
6
Capacity Must be able to hold around 5 gallons or more of run-off water per day
6
Reproducibility The structure could be reproduced by CCAT volunteers
7
Usability Water is clean enough for plant uptake
9
Cost Does not exceed a budget of $250
5
Functionality Successfully captures and stores water run-off
8
Maintain Seedling Integrity Water is successfully diverted away from seedling bed under the platform
10

Literature Review[edit]

This is a review of the available literature pertinent to water reclamation systems.

Basics[edit]

Water reclamation from different sources, such as wastewater, groundwater, and rainfall is a way to relieve water needs across the globe. [1] Water reclamation is a system that recycles or reclaims water. The implementation of such a system has many different forms. Whether the system collects rainwater, runoff, or excess water from gardens they will share similar qualities within their design and construction.

Concerns[edit]

There are different concerns involving water reclamation. It is important to understand the path that the water has traveled to prevent changes in its water quality. Another issue is the comfort or acceptance of reusing water. Some may prefer an additional filtration system which increases the cost. Increase in cost may be an issue for some communities. Other concerns include the transport of water and whether or not a pump is needed. Not only is this another expense, but also spatially demanding.

Sources of Reclamation[edit]

Sources of water for reclamation are rainwater, wastewater, industrial groundwater, urban stormwater, desalinized seawater, and irrigation return water. [1]

Types[edit]

As mentioned above, water reclamation can take many forms. Below I will elaborate on the three main types. It is important to note that there are many sub categories of system types within each of these types.

Potable Reuse[edit]

For water to be considered potable it needs to go through a filtration process to ensure that contaminants are at a minimum level. Drinkable water may require additional filtration and disinfection. One can make their own filter out of a variety of natural materials, such as sand. [2] The gravity sand filter is effective in cleaning water and inexpensive to build. It is an opened topped and partially filled with gradient sand and gravel sizes. The water travels with a downward flow. The downside of this mechanism is that it is slower and requires a large area.

Nonpotable Reuse[edit]

Nonpotable water is more simple when compared to potable water. It is also simple to reuse. A system like this requires a dual distribution system so that potable and not potable water can be transported separately. This water can be used for any sector (residential, commercial and industrial). The extent to which we would filter this water is to separate debris with a screen. This water would most likely be used to rehydrate plants.[3] Separation of debris by flotation is another mechanism. That would be our main goal to make re watering plants less intensive. Sediment tends to sink to the bottom. Using this to our advantage, debris-free water can be transported to the storage container by diverting water through an overflow. [4]. PVC Piping is one of the most common uses to transport water in water reclamation systems.[5]

De Facto Reuse[edit]

De facto reuse is when the natural water source is the water supply and the resulting wastewater is returned. This is a common method amongst the dry regions.

Reclaimed Water Uses[edit]

After the water is reclaimed from the sources above, it may be used for applications that do not require high-quality water such as toilet flushing, irrigation, vehicle washing. Augmentation of this water can be used for current or future needs, protecting aquatic ecosystem flows, and recharging groundwater. [6] In 2009, use of reclaimed water substituted for more than 127 billion gallons of drinking water while serving to add more than 79 billion gallons back to available groundwater supplies. Using reclaimed water for non-drinking purposes extends our freshwater supplies and ensures sustainable use of a vital natural resource. [7]

Prototyping[edit]

To prototype the project, we continuously searched through the materials available at CCAT and compared how various items could be used to satisfy the general design ideas. Materials like wood pieces, gutter sections, various screws, and nails, etc. were taken from CCAT's supply of upcycled materials and brought into the greenhouse to assess an item's compatibility with our design. From here, group members would discuss their ideas of how a component could be used for the system. Upon group consensus, a component would be physically modified to fit the system (if necessary) and installation was completed. If the component worked as desired, it was incorporated into the final design. However, if it did not, then members continued to search CCAT for other viable components. Missing components were bought from the local retail store.

Construction[edit]

ImageStep
Fixed surface to support catchment trays Step 1 : Create a fixed surface on each end of the table.

Pieces of wood were fit into the width space between the table's legs by making cuts to each short side of a wood piece using a circular saw. We made rectangular cuts to pieces of wood with a width greater than that of the table's legs to create a protruding lip on the inside of the legs, which extends the shelf space available for support. A measuring tape or ruler should be used to accurately mark the dimensions needed to cut and fix a piece of wood to the table's legs.

Support brackets attach a wood board between a table's legs Step 2 : Use L-shaped support brackets to attach the surface to the table.

Use a power drill or phillips-head screwdriver to drive screws through the brackets, fixing them onto the bottom of the piece of wood. Measure and mark the space needed to fit an inclined catchment surface between the gardening table top and fixed surface, then adjust the placement of the wooden piece to the desired height. Use a level to ensure that the piece of wood is level and then drive screws through the remaining bracket holes to fix the wood piece to the table's legs.

A side view of the system's catchment components Step 3 : Add supports for an inclined catchment surface to attach to.

Measure the length needed for a front and back support to lay across the fixed surface. The back piece of wood is cut to lay across the entire length of the fixed surface, while the front piece is cut to fit the length between the table's legs. The back piece of wood is where the top of the inclined catchment surface will attach and the front piece of wood will be used to rest the lower end of the catchment surface on. So, the back support should have a good vertical height while the front support should have a good horizontal width. The supports are not fixed down.

Row of catchment trays underneath a gardening table Step 4 : Attach an inclined catchment surface to the supports.

Use a staple gun to place two or three staples along one short edge of a gardening tray, fastening it to the back wooden support. Staples should be placed to allow the top edge of the tray to align with the top edge of the back support. The tray's other short side should rest on top of the front support created in Step 3. Attach trays to the back support until a row underneath the table has been created. It is advised not to attach one tray on either end of the row, as this allows for the tray to be readily removed and the rest of the trays fixed to the back support can be removed as one piece. Using a pair of scissors or knife, perforate holes along the lower edge of the trays and widen them to the width of a finger.

Gutter directs water from catchment trays to storage tank Step 5 : Use a gutter to direct water from the catchment surface toward a storage tank.

Cut a piece of gutter to the length of the gardening table and then cut the gutter in half to create a C-shaped gutter. Use a staple gun to staple the gutter to the legs of the table at an incline, so gravity draws water through the gutter and toward a storage tank. The gutter can be extended out from the table's legs by fitting and screwing wood blocks onto the legs where the gutter needs to be stapled.

A plastic automotive oil tray captures water from the gutter Step 6 : Divert water from the gutter to the storage tank - refer to the video demonstration for a visual reference.

Use scissors to cut the top corner edges off the gutter. Start one centimeter below the edge and cut for a length of two inches. Pinch the gutter's edges to fit a 90 degree PVC fitting onto the gutter's end. Extend a straight piece of PVC pipe from the 90 degree PVC fitting down to the storage tank. Cut two 3x3 inch squares of fine plastic mesh and secure two layers of mesh over the open end of straight PVC piping with rubber bands.


Timeline[edit]

This is the timeline of our project.

Date Description
March 6 Meet with CCAT
March 10 Identify the need and propose design components, initial prototype complete
March 13 Meet with CCAT
March 17 Refine prototype with Gardeners/CCAT
March 27 Meet with CCAT
March 30 Obtain all materials and double check with Gardeners/CCAT
April 3 Meet with CCAT
April 6 Present blueprints to Gardeners/CCAT and begin construction
April 27 Complete construction and install project
May 4 Refine project and work on write-up
May 10 Finish write-up and submit write-up
May 14 Present project

Costs[edit]

The costs listed are primarily materials for the construction of the system. It does not account for the cost of our time and the time of the CCAT team in assisting us. It is, important to recognize that this is only a proposed budget and it is subject to change as our plans progress. A range of financial options is available for change in capital cost over time. For example, investment in sturdier, and more reliable valves. CCAT has a budget of $250 and we have a goal to get below that number.

By the end of our project the only materials purchased were the 12" x 22" plastic trays for catchment ($2.16), the plastic oil tray ($12.58), and brackets ($3.00). This leaves us with a total cost of about $30.00 plus tax for the entire system.

Item Price Quantity Total
12" x 22" Gardening Trays $2.16 7 $15.11
Brackets $0.30 4 $6.00
75" Rain Gutter Reused 1 $0.00
Plastic Oil Tray $12.58 1 $12.58

Operation[edit]

The reclamation system operates by channeling runoff water from the upper shelf of the greenhouse table with a row of inclined gardening trays fixed underneath the shelf. The trays feed water directly into an inclined gutter that leads to an automotive oil tray catchment.

System Maintenance[edit]

To reduce the accumulation of particulate matter within a water reclamation system it is recommended to flush out the material using a pressurized flow of water. This should be done regularly to maintain a functioning system. The injection of chemicals like chlorine into an irrigation system is often used to flush out material. However, such applications go beyond the scope of CCAT's operational interests. Conducting water quality tests of irrigation water such as pH, biological and chemical oxygen demand, transparency, etc. would be an effective way to determine the presence of water contamination. This will also check the viability of using reclaimed water for irrigation within the greenhouse. Since the system is just a demonstration size, most of the maintenance concern is being able to clean out the debris. The mechanism that we designed can be removed from under the table to be wiped down. The water channels from the catchment surface are large enough to where most of it will have fallen into the screen at the end of the gutter.

Schedule[edit]

The system should be maintained using the following procedures at each given time frame.

Daily
  • Lightly flush resting debris off catchment trays and gutter
  • Visually observe whether the system functions properly when watering plants
Weekly
  • Remove filter screen at end of straight PVC pipe and rinse it of debris.
  • Wipe down the gutter with a rag to clear any sediment build up.
Monthly
  • Remove catchment trays and the PVC pipe to rinse away debris over plants needing water.
  • Replace filter screen as necessary.
Yearly
  • Assess each component used in the system and replace any components that are worn out.
How to Maintain The Water Reclamation System
ImageStep
Row of catchment trays underneath a gardening table Step 1 : Remove the left and rightmost trays (unfixed) in the row, then remove the back wooden support with the remaining trays attached. PVC piping readily detaches from the gutter and may be cleaned of debris caught by mesh or inside piping.

Conclusion[edit]

Testing results[edit]

During Testing, our project went through about 3 big changes. The Initial change happened at the hardware store when we went to find our catchment material. The proposed catchment surface was going to run long-ways on the bottom level of the table with a drainage portion on the end of this piece. What we found was that sizing a catchment tray was difficult given the dimensions of the table. The adaptation that took place was replacing the single, long tray for 6 horizontally running trays that transport water to a long-way gutter system, then to the catchment reservoir. The second change occurred when we were trying to put a seedling surface that was above the catchment surface. One CCAT advisor suggested having the catchment surface be on the bottom, therefore, increasing the amount of reclaimed water. However, another CCAT advisor had less confidence about this design, feeling that the drop distance would still be harmful to the seedlings. The final decision for this portion of the design integrated our same horizontal design but wedged up under the bottom of the first (top) shelf of the table. The third change came as a response to the previous changes listed above. The original design included a subducted catchment reservoir to allow enough head for the water to flow into the catchment from a low entry point (6 inches). Because the system has been raised to near the top of the table, there was no need to subduct the catchment reservoir.

Discussion[edit]

The results of testing and change were produced through table watering tests where 5 cups of water was poured over the planted table and over two catchment trays. The yield of this test was about 2 cups. Because of how much the plants and table retain water, we were expecting to get lower output than input. The testing process of the physical system was the most challenging part of this project. Due to design alterations and implementing feedbacks, the testing process took the most time to get done. This took us by surprise as our group had confidence in our first designs of the system.

Lessons learned[edit]

This project introduced changes that were not always expected. From brainstorming to implementation, the process showed that smooth sailing is almost never the case. Mostly towards the end sections of the project, the team learned that communication and cooperation were the key factors to success. We also learned that we didn't give ourselves enough time for the testing process. An extra 10 hours of testing would have been ideal for this project, as the final portions were rushed and some things were overlooked. Group meetings and CCAT meetings were not as prioritized as they should have been and also would have been more beneficial to the project. The learning curve of having a whole project was a process that taught our group many lessons along the way.

Next steps[edit]

The next steps will be to continue learning about appropriate technology and renewable resources as well as incorporate these techniques into our own lives. Teaching others about our project. Encouraging other people to be involved in sustainable and appropriate technology projects like CCAT. Another important step that should be taken is to continue research and supporting appropriate technology projects in our own communities.

Troubleshooting[edit]

Problem Suggestion
Lack of flow out of catchment trays Clear large debris from trays and flush smaller debris towards the drainage area
Clogged trays, not draining Re poke the drainage holes with a nail or screwdriver

Widen tray drainage holes if necessary to increase flow

Pooling on catchment reservoir Clean off debris and reset the inflow valve to allow flow

Video Demonstration[edit]

Team[edit]

Humboldt State University spring semester 2019. The Four Peppers:

References[edit]

  1. 1.0 1.1 Novotny, Vladimir, Ahern, Jack, and Brown, Paul. 2010. Water Centric Sustainable Communities: Planning, Retrofitting and Building the Next Urban Environment. Hoboken: John Wiley & Sons, Incorporated. Accessed February 20, 2019. ProQuest Ebook Central.
  2. Huisman, L., and W. E. Wood. World Health Organization." Slow Sand Filtration, 1974. Accessed February 20, 2019.
  3. Grafman, Lonny. To Catch the Rain: Inspiring Stories of Communities Coming Together to Catch Their Own Rain, and How You Can Do It Too. Arcata, CA: Humboldt State University Press, 2017.
  4. Aulenbach D., Shammas N.K., Selke W., Wang L. (eds) Wastewater Renovation by Flotation. In: Flotation Technology. Handbook of Environmental Engineering, vol 12. Humana Press, 2010
  5. "Vinyl in Building and Construction." Building With Chemistry. Accessed February 21, 2019. https://buildingwithchemistry.org/chemistry-in-bc/vinyl-in-building-and-construction/.
  6. Asano, Takashi, Franklin Burton, and Metcalf & Eddy. Water Reuse: Issues, Technologies, and Applications. New York: McGraw-Hill, 2007.
  7. Lusk, Mary. "Reclaimed Water: Frequently Asked Questions." UF/IFAS Extension Flagler County. June 29, 2017. Accessed February 21, 2019.