Sanitation in the Circular Economy – an integrative-modular-onsite toilet treatment for recovery of NPK fertilizer, carbon and water
Implementing Organization
Indian Institute of Technology (IIT)
Principal Investigator
Dr Indumathi M Nambi
Professor
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Indian Institute of Technology (IIT)
CO-Principal Investigator
Dr Tiju Thomas
Assistant Professor
CO-Principal Investigator
Dr Devasena M
Associate Professor
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PSG Institute of Technology and Applied Research, Salem
CO-Principal Investigator
Dr Divyapriya Govindaraj
Indian Institute of Technology (IIT)
Environmental Engineer
About
Environmental sanitation is a significant public health issue in India that is still lagging far behind many countries. The government has embarked on a mission to make India Swachh by October 2nd 2019. Many attempts to deal with sanitation issues have faced challenges which are fuelled by inadequate water and improper maintenance. Undiluted human waste (urine & faeces) is a potential source of Nitrogen (N) and critical, non-renewable Phosphorous (P) and soil amendment. Presently the valuable nutrients are flushed into the sewer systems. About 80% of N & 60% of P load to wastewater treatment plants are contributed by human urine. On the other hand, India imports about 80% and 100 % of phosphorus and potassium respectively for agriculture and often pay a very high price. Nutrients from urine can cater to about 22% of the global P demand. Currently these nutrients are flushed into sewer which often is treated only with the intention of removal and not recovery. The project explores the techno-economic feasibility of zero energy process by unlocking circular potential in sanitation thereby achieving Swachh Bharat mission & enables societal welfare. The work yields three major end products NPK fertilizer, enriched carbon and recycled water. The integrated zero energy process is a holistic approach which can be upscaled into a profitable entrepreneurial element. Scope and methodology: 1. Onsite treatment starts by collecting liquid and solid resources through waterless urinals and urine diversion toilets. 2. Nitrogen in the form of ammonium liquid will be harvested from source separated urine by Solar Powered Distillation. 3. Phosphorus is harvested in the form of struvite in the automated struvite reactor fitted with magnesium dosing pumps. 4. Carbon as soil amendment from solid waste by Black Fly Larvae Composting Technique, removing process residuals and recovering water for flushing by Electrochemical method. 5. Economic values of the products and circular economic potentials. 6. A spreadsheet-based life cycle assessment model will be developed to track the impacts of design and operational decisions. Utility, Justification & Anticipated impact: The proposed modular toilets can be referred as first of its kind in saving water along with nutrient recovery and fecal sludge management. Earth's inexpensive phosphorus assets are anticipated to be exhausted in 50–100 years and P is estimated to be in very high demand by 2030. The fertilizer import can be entirely eliminated by the struvite recovery from urine. The technical solution of electrochemical oxidation tackles water supply crisis and makes the system to be self-sustainable. The project explores the techno-economic feasibility of zero energy process by unlocking circular potential in sanitation thereby achieving Swachh Bharat mission and enables societal welfare. The work yields six major end N, P, K, ammonium solution, water for reuse and soil amendments.