Development of Enhanced Digestion and Multi-Stage Bioreactor (EDMSB) reactor for faecal sludge and septage treatment: A pragmatic low-cost and space saving robust technical solution for developing countries 

Abstract

In developing countries like India, a tremendous thrust is observed on installation of sewage and septage treatment, which is an essential requirement for environmental protection . However, many cities, urban and rural areas do not have proper sewerage network facilities and subsequent sewage treatment plants. Septic tank, twin-pit toilets, etc. are the onsite soltions of wastewater management. In this context, the major chalanges is associated with the safe disposal of treated/partially treated sludge of onsite treatment facilities to prevent environmental pollution from highly contaminated faecal sludge or septage.Faecal sludge treatment plant with different technologies are adopted in different areas, although a pronounced challenge is associated with the efficacy, economy, land requirement and effluent quality meeting the desired effluent or discharge standard. In the present research, a novel “Enhanced Digestion and Multi-Stage Bioreactor (EDMSB)” is developed as an efficient and cost effective technolgy with less plant foot print  (Indian Patent No: 202331055337).EDMSB is based on advanced hybrid system of anaerobic digestion for sludge and solid-liquid separation followed by moving bed bio-reactor based aerobic treatment associated with inclied plate-settler and denitrifyning unit for the treatment of supernatant water. Suitable pre- (screen, non-degradable fraction and scum removal unit) and post-treatment (multi-grade filtration, activated carbon filtration and ozonation) are provided to enhance the treatment facility and to meet the reuse/disposal standard. The novelty of the proposed invention lies in its unit design and appropriate process flow circumscribing compactness, modular arrangement, cost effectiveness, efficiency and space saving set up. The system is capable to handle the variation of faecal sludge characteristics, i.e., fresh faecal or partially/mineralized sludges from septic tanks with cleaning intervals of wide variation. EDBSM exhibited a significant efficiency (BOD >99%, COD >99%, TSS >99%, Faecal coliform >99%, TKN>98%) for the high pollunat load of fresh faecal or septage. In addition, the proposed system has also established a significant reduction of cost (Capital cost~60% and operation cost~70%) and land requirement (> 80%) compared to other popular technologies like phytorid based system. The units of proposed inventions are completely odorless as compared to other technologies adopted in field and free from flying nuisance which creates a better working environment for the plant operators and maintains an immaculate surrounding environment. The stabilized sludge volume is very low which creates a significant reduction in the sludge handling facility. The quality of digested sludge ensures its use as good manure. The present invention brings an significant advancement in faecal sludge and septage management, which can be adopted in various developing countries like India as an efficient, cost-effective and space saving opportunity in this field.     Keywords: Faecal sludge and septage management, Anearobic digestor, Moving bed bio-reactor, Environmental pollution, Aerobic and anaerobic treatment