Nouveau design solar septic tank: Reinvented toilet technology for sanitation 4.0

The up-flow solar septic tank (UTST) and multi-soil layering (MSL) system has been developed and proposed as “Nouveau Design Solar Septic Tank”. The objective of this study was to verify functionality of the integrated UTST and MSL system for treatment of toilet wastewater (or black water) under actual conditions over a year at the Asian Institute of Technology campus, Pathumthani province, central Thailand. During the operation period which involved fluctuating flow rates, ambient temperatures and black water characteristics, the UTST unit yielded satisfactory performance with the average treatment efficiencies of 92 [Formula: see text] 10% for total chemical oxygen demand (TCOD), 79 [Formula: see text] 10% for soluble chemical oxygen demand (SCOD), 93 [Formula: see text] 9% for total 5-days biochemical oxygen demand (TBOD) and 90 [Formula: see text] 12% for soluble 5-days biochemical oxygen demand (SBOD), respectively, while the MSL unit could remove 95 [Formula: see text] 3%, and 88 [Formula: see text] 15% of total kjeldahl nitrogen (TKN) and total phosphorus (TP), respectively. The effluent TCOD, TBOD, TKN, nitrite (NO(2)-N), nitrate (NO(3)-N), ammonia (NH(3)) and TP concentrations of the integrated UTST and MSL system were 39 [Formula: see text] 27,8 [Formula: see text] 27,5 [Formula: see text] 5 mg/L, 2 [Formula: see text] 2,39 [Formula: see text] 24,8 [Formula: see text] 9,2 [Formula: see text] 5 and 1 [Formula: see text] 1 mg/L, respectively, meeting the ISO requirements. The removal efficiencies of TCOD, SCOD, TBOD and SBOD exhibited positive correlation with the ratios of TBOD/TKN, TBOD/SBOD and TBOD/TP. With high treatment efficiencies and effluent quality meeting the ISO requirements, the nouveau design solar septic tank has been demonstrated as an innovative technology toward the sanitation 4.0 concept and the Sustainable Development Goal no. 6 (SDG6).