Earth, Atmosphere & Environment Sciences
Title : | Sanitation in the Circular Economy – an integrative-modular-onsite toilet treatment for recovery of NPK fertilizer, carbon and water |
Area of research : | Earth, Atmosphere & Environment Sciences |
Focus area : | Environmental sanitation |
Principal Investigator : | Dr Indumathi M Nambi, Professor, Indian Institute of Technology (IIT) Madras |
Timeline Start Year : | 2020 |
Contact info : | indunambi@civil.iitm.ac.in |
Details
Executive Summary : | 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. |
Co-PI: | Dr Tiju Thomas, Assistant Professor, Dr Divyapriya Govindaraj, Environmental Engineer, Indian Institute of Technology (IIT) Madras, Dr Devasena M, Associate Professor, PSG Institute of Technology and Applied Research, Salem |
Total Budget (INR): | 69,07,027 |
Achievements : | Prototype fabricated, Urinals converted to waterless urinals and Collected urine was taken to prototype for running Trial experiments. Based on learnings from initial trials, modifications to the unit were undertaken Experimental Conditions: Optimum dosage of MgO : 3.75 g / liter of Cow urine, pH : 9-10, Optimum time : 2 hours, Quantity of struvite : 22.5 grams, Electrical conductivity(Ec) of decanted urine : 40mS. Phosphate analysis of decanted urine by spectrophotometer unveiled that 80% of phosphates in urine has been removed/recovered as struvite |
Organizations involved