In present scenario black water is one of the vital pollutants in environment. And recycling of black water is quiet expensive. If handledsmartly this solid waste can be converted into very good manure and can be used in agricultural fields.Moreover human faeces gives the most nutritious compost because of the varieties of our diet.
What is the relevance of Dry compost toilets today?
• It saves water by minimalizing the use of water.
• Human faeces being rich in ammonia it provides us with rich manure that is a very good quality compost that can be used in agriculture.
• It generates revenue if done in huge scale (public toilets).
Essential components of dry compost toilets:
1. Commode with separate pee hole, poop hole and bum wash basin.
2. A compost storage area – Currently either a compost pit or a barrel system is widely used as storage for composting human faeces.
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3. A chimney to take out the hot air rather than letting hot air escape into the toilet room through poop hole.
4. Saw dust storage.
How do we convert human faeces into compost?
• The faeces should be humid but not wet for the same to become compost. Thus ideally it is effective to separate urine and bum wash waters from faeces. Every time after using the toilet the faecesis covered with saw dust or dry leaves to keep the wetness away.
• It should be maintained at hot temperatures within the range of 40 degree Celsius and 60 degree Celsius. This temperature enables bacteria (thermophylllic) that oxidizes the waste and eliminates pathogens to thrive. The maggots eat the undigested food scraps in faeces and break it down more for bacteria to take over.
• With these parameters compost will be ready in 6 months.
DESIGN AND CONSTRUCTION OF DRY COMPOST TOILET ON SITE:
• We designed with compost pits rather than using barrels.
• It was designed in such a way that there are two useable toilets at any given point of time.
• Each of the toilets have two commodes and a compost pit for each of the commodes.
• It was designed in such a way that one of the commodes in each toilet blocks will be shut for 6 months after it will be filled up with faeces. By the time the second commode will be filled the faeces in the first pit will become compost and will be free for usage.
We elevated the toilet slab to a height of 1.2M, to get a space for compost pit at ground level so that removing compost becomes.
• Firstly we marked the foundation, one and half feet wide and 1 foot deep for the compost pit wall.
• After digging the foundation pit, rubbles of variable sizes were used in the foundation along with cement mortar.
• The compost pit walls were made up of random rubble masonry with lime mortar and plastered with lime plaster to make it waterproof.
• To trap heat and hence speed up the composting process a tilted window with translucent glass pane was provided.
• For the elevated toilet slab and overhead tank we built 4 huge pillars of 3 feet X 3 feet made by placing the sandstone slabs on each other. We used sand stone pieces asthey were available in excess as waste from construction of Matrimandir.
• The bamboo beams for the toilet slab were placed into these pillars.
• Bamboo reinforcements of the slabs were laid on the bamboo beams with tying done by coconut ropes.
• To support the slab vertical bamboo posts were used.
• Scaffolding for the concrete cast was laid using tetrapack sheets.
• Concrete mix was poured in the cast and cured.
• For walls a visual barrier was all we needed. Thusa simple frame of bamboo poles wasconstructed and palm leaves were used to provide a visual barrier.
• For toilet door we used marine ply -wood frame and with flattened tetrapack boxes.
• The toilets were left open to sky without roof.
We had to replace the palm leaf with a strong permanent wall and also provide a roof and thus we constructed wattle and daub as exterior walls for the dry compost toilet block:
Wattle of the toilet block is a frame work made of palm reeds by tying them with coconut ropes in a manner that it makes frames of palm reeds.
1. And into this frame palm reeds were woven.
2. Palm reeds were used because they don’t get attacked by termites even after it gets wet.
3. Wet mix of cob was used as daub.
4. The daub was applied from both sides oof the wattle.
5. While it was still wet put some artistic skills to create some art work using hands and by sticking some pebbles.
6. Then it was left to dry. It was plastered with wet mud as we had enough over hangs to protect it from rain.
We put together a framing roof structure from locally harvested bamboo. The shape of the roof is sloped on three sides from the center like a pyramid cut in half.
1. The holes were punched and J-Bolts were pierced through the sheet. The nuts were tightened.
2. We made sure that we punched the holes on the ridges in the sheet. This way chance of leakage was avoided.