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Testing synthesized components of rainwater harvesting systems with Isla Urbana

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Ajusco Labs
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The Laboratory of Community Alternative Technologies at Ajusco
Rainwater harvesting system installed in Mexico City in colonia Cultura Maya
Zach Estela lab technician at Ajusco Labs
Isla Urbana
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Intro[edit]

The following is a list of goals, test procedures, equipment needed, and goals for testing synthesized components of rainwater harvesting systems and how effective each componenet in the system is at removing contaminants. This is one test in a series of tests of rainwater, grid water, and store bought garafon drinking water quality at The Laboratory of Community Alternative Technologies at Ajusco in conjunction with Isla Urbana. Both groups are non profits in association with International Renewable Resources Institute-Mexico located in Mexico City. Isla Urbana is a group providing rainwater catchment systems around Mexico City and other areas of Mexico, Ajusco Labs is a laboratory testing center for appropriate technology projects and outcomes. Ajusco Labs will be testing rainwater quality outcomes from Isla Urbanas systems set up around Mexico City. This is one part in a series of rainwater testing at Isla Urbana and Ajusco Labs. Click here to connect to the main page on Rainwater quality testing.



Abstract:[edit]

Different catchment characteristics and components in rainwater harvesting systems have been found to have statistically significant effects on total coliform bacteria levels as well as heavy metal levels, and other contaminants. [1][2] Atmospheric influences have also been found to effect the ending water quality from rainwater. The point of this study is to understand the atmospheric influences on the rainwater quality found in Mexico City, the effectiveness of contaminant removal by different components including the first flush and different filter types, and the overall ending water quality after water passes through different types of synthesized filter sequences found in Isla Urbana’s rain catchment systems. Variables in the field that can not be accounted for with this testing procedure include inefficiencies that might be found in an actual first flush and how different pumps effect the speed of water through the filters and thus changes the removal rate of the filter. The benefits of this testing is that it can be done in a location with or without a rainwater harvesting system because we will be synthesizing the components of the system in the laboratory using samples collected from rooftops around Mexico City, this greatly helps increase the number of samples we can collect, since these samples are limited to being taken only during the rainy season. We will take random samples from at least 15 houses over the course of the rainy season and compare them against both water potability and recreational water standards by the World Health Organization (WHO) and the Environmental Protection Agency (EPA).

rainwater, water quality, rainwater harvesting, Mexico City, contamination,


Goals:

  • Understand the atmospheric influences on the rainwater quality.
  • Understand the effectiveness of contaminant removal by the first flush, make sure to write the date because this will change depending on if it was during the first rains or the last of the season.
  • Compare contaminant removal rates from different filters.
  • Understand the overall ending water quality after water passes through different types of synthesized filter trains.

Variables in field that are not accounted for with this testing system include:

  • different pump types, from gravity fed to 2 horse power pumps in the field, this changes the speed of water through the filters and thus the removal rate of the filter.
  • inefficiencies that might be found in a regular first flush


Equipment:[edit]

  • 9 clean 25 gallon buckets with lids (food grade)

or could just have at least 3 buckets and need to clean the same bucket 6 times to finish the process

  • Timer
  • Plastic Piping for water (? length and ? diameter)
  • 3/4ths horse power pump
  • 2 Sediment Filters including:
    • 1 Pleated sediment Filter (write down the age)
    • 1 Gravel sediment Filter (write down age)
  • 1 Carbon Filter (write down the age)
  • 9 sterilized 500ml sample containers
  • Icebox for storing fresh samples
  • Ice to put in icebox
    • equipment and reagents as specified in the colorimeter manual for each parameter

Test Timing within the Year:[edit]

Rainy Season

Sampling Sites:[edit]

  1. On top of roof (In order to get sample of rain before touches system and to understand atmospheric influences on rainwater quality)
  2. Below Gutters (in order to get sample of roof and gutter influence on rainwater quality)


Process:[edit]

  • Watch the weather, you want to place 2 of the sample buckets before it starts raining and the third sample bucket ten minutes after its started raining.
  • Place one 25 gallon bucket on top of the roof in order to catch the first 10 minutes of rain.

This rain water has not touched the system and it tells us initial quality of the water and the atmospheric influences effecting the rainwater quality. This gives us a base line to compare our ending rainwater with.

  • Place another 25 gallon bucket under the gutter in order to catch the first ten minutes of rain. This will synthesize the water quality found in the first flush.
  • After the first 10 minutes of rain remove the 25 gallon bucket from under the gutter or put a lid on it to prevent further rain entry. This will make sure that this water quality only represents the water found in the first flush.
  • Also after the first 10 minutes of rain place the third 25 gallon bucket under the gutter. This will act as the water quality found entering the cistern after the first flush has removed the first ten minutes of rainwater contaminants.
  • Fill this third bucket until it is 3/4ths full.
  • Take samples from all three buckets in 500ml containers, write the date, and label them:

Bucket 1 = AtmosphereR (Atmosphere Rainwater), Bucket 2 = First FlushR BP(First Flush Rainwater Before Processing) Bucket 3 = After FFR BP(After First Flush Rainwater Before Processing)

  • Put a lid on Bucket 3 to return to the laboratory for further processing and analysis of water in bucket and water in sample containers, but dump out water from bucket 1 and 2.
  • Assemble the plastic tubing, water pump, filter, and buckets... (Enrique can you elaborate on how the specifics of how the tubing and pump and filters can be placed together

Sample bucket - tubing- water pump - tubing - one filter - tubing empty bucket

  • Now with water from the third bucket place only half of this water in another bucket (bucket 4). This allows us to do different types of processing on the same sample.

Combo 1.
1 pleated sediment filter

  • Place the plastic tubing in this bucket 4 and pump this water through the first pleated filter into an empty bucket 4b.
  • Take a sample of this processed water in one of the 500ml containers , write the date, and label it

After FFR Pleated HP1 (After First Flush Rainwater Pleated Sediment Filter and 1 Horse Power Pump)

Combo 2
1 pleated sediment filter + 1 carbon filter

  • Now take the rest of the processed water from bucket 4b and run it through the carbon filter into an empty bucket 4c.

This will synthesize the sequence found in normal systems at Isla Urbana where water first passes through a sediment filter and then a carbon filter.

  • Take a sample of this processed water from bucket 4c into a 500ml container, write the date, and label it

After FFR Pleat + Carbon (After First Flush Rainwater Pleated Sediment Filter + Carbon Filter + Micropore Filter)

Combo 3
1 pleated sediment filter + 1 carbon filter + 1 micro-pore filter

  • Now take the remaining water from bucket 4c place the plastic tubing in the bucket and pump the water through a micropore filter into an empty bucket (4d).

This will synthesize the sequence of water filtered through the pleated filter and carbon filter followed by the micropore filter.

  • Take a sample of this processed water from bucket 4d into a 500ml container, write the date, and label it

After FFR Pleat + Carbon + MicroP (After First Flush Rainwater processed through a Pleated Sediment Filter + Carbon Filter + Micropore filter)


Combo 4
1 pleated sediment filter + 1 carbon filter + 1 micro-pore filter + 1 UV filter

  • Now take the remaining water from bucket 4d place the plastic tubing in the bucket and pump the water through a UV filter into an empty bucket (4e).

This will synthesize the sequence of water filtered through the pleated filter and carbon filter followed by the micropore filter and then the UV.

  • Take a sample of this processed water from bucket 4e into a 500ml container, write the date, and label it

After FFR Pleat + Carbon + MicroP + UV (After First Flush Rainwater processed through a Pleated Sediment Filter + Carbon Filter + Micropore filter + UV filter)

Combo 5
1 gravel filter

  • Now with the other half of the water remaining in bucket 3 that has not been processed at all, place clean plastic tubing in the bucket and pump it through a gravel filter into an empty bucket 3b.

This will act as the water quality found as water from the cistern then is filtered through the first gravel filter.

  • Take a sample of this processed water from bucket 3b into a 500ml container and label it

After FFR Gravel (After First Flush Rainwater processed through a Gravel Sediment Filter)


Your samples list should include:

  1. AtmosphereR (Atmosphere influenced Rainwater),
  2. FFR (First Flush Rainwater)
  3. After FFR BP(After First Flush Rainwater Before Processing)
  4. After FFR Pleat (After First Flush Rainwater processed through a Pleated Sediment Filter)
  5. After FFR Pleat + Carbon (After First Flush Rainwater processed through a Pleated Sediment Filter and Carbon Filter)
  6. After FFR Pleat + Carbon + MicroP (After First Flush Rainwater processed through a Pleated Sediment Filter + Carbon Filter + Micropore filter)
  7. After FFR Pleat + Carbon + MicroP + UV (After First Flush Rainwater processed through a Pleated Sediment Filter + Carbon Filter + Micropore filter + UV filter)
  8. After FFR Gravel (After First Flush Rainwater processed through a Gravel Sediment Filter)
  • Test samples along the parameters in Section 2, parameters will be tested according to the colorimeter manual.
  • For coliform testing samples must be tested within 6 hours.
  • Reagents used in the testing may be toxic and will need careful disposal, check the colorimeter manual for proper disposal and check Section 3 for locations and contact information for the proper disposal organizations in Mexico City.


Results[edit]

Pending, this study will begin with the rainy season in May 2011.


References[edit]

  1. Dillaha, Theo A. III, and Zolan, William J. Rainwater catchment water quality in Micronesia. Water Research. Vol. 19, no. 6, 1985, pp. 741-746.
  2. Thomas, P R and Greene, G R. Rainwater quality from different roof catchments. Water Science & Technology. Vol. 28, no. 3/5, 1993, pp. 291-299.