Dr Parag Sadgir, Professor in Civil Engineering Department, College of Engineering, Pune, and his research scholar Mr Priyanad Agale had applied for the patent for their invention entitled "Self-Purification Based Polluted Water Purification "wide application no. 201621007499 dated 03.03.2016. The Patent Office granted the said patent to, Government of India, Mumbai, on 30th  April 2021 with Patent No. 365518. The open channel polluted water purification system comprises a tide generating structure, a plurality of baffle walls in varying width combinations and patterns, consisting of pebble and sand, an Up and downflow filtration mechanism, and a final filtration tray. It consists of five stages of the purification process designed on the principle of gravitational flow. The present invention is useful for domestic wastewater treatment in which the main principle is the self-purification of wastewater. No chemicals are used in this process or a system for wastewater treatment. The materials/media used in this process are selected from locally available materials such as brickbats, pebbles, sand, and coconut coir. This system is a decentralised eco-friendly domestic wastewater treatment system. The main logic of this purification system is to accelerate the fundamental process of self-purification, that is, equalisation, aeration, sedimentation. The system can be constructed in brick masonry, stone masonry, R.C.C., soil bunds, or fabricated in fibre or Ferro-cement material. In this system, after treatment, B.O.D. Removal efficiency is 88-90%, and C.O.D. removal efficiency is 89-90%. For this system, the land requirement is 0.75 m2 per 1 m3, and the cost varies from Rs. 4000 to Rs. 5000 per m3 of wastewater. Treated wastewater can be reused for farming and gardening etc .

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