Thiruvananthapuram: The city corporation and the Kerala Water Authority are exploring options to set up Japanese decentralised wastewater treatment plants known as ‘Johkasou’ in the city.
At the river rejuvenation committee (RRC) meeting held in April, KWA MD informed that KWA is jointly taking steps with the corporation for setting up Johkasou facilities at the KWA office at Vellayambalam. According to the minutes of the RRC meeting held in February, the chief secretary had directed the KWA to look into the possibilities of Japanese underground models of STPs. The secretary, water resources department, had informed that he shall visit the Johkasou plants implemented in Delhi.
The Union cabinet had in April 2022 given its ex-post facto approval for a memorandum of cooperation signed between India and Japan in the areas of decentralized domestic waste water management
The collaboration with Japan was mainly mooted in areas such as decentralized domestic wastewater management and effective reuse of treated wastewater using Johkasou technology.
The decentralized Johkasou system of management of wastewater can have greater implications for management of grey (domestic wastewater) and black water (wastewater from toilets) from settlements with coverage under Jal Jeevan Mission as well as the sustainability of sources of fresh water under the mission. It will help urban local bodies to plan better for the complex issue of treating waste water, a PIB press release said.
As per a case study document by Asian Development Bank Institute, Johkasou is a decentralized wastewater treatment system that treats human waste from flush toilets and domestic wastewater.
Initially developed exclusively for flushing toilets, Johkasou treated only black water and bridged the gap until the public sewerage system was installed. The long period of construction and the large budget required to build a public sewerage system in addition to the poor economics of managing wastewater treatment using only the public sewerage system and the collective management method made apparent the need for an alternative system. Hence, the Japanese government revisited the concept of Johkasou as a small, decentralized wastewater treatment system to serve housing areas and consequently introduced the type of Johkasou that could treat both human waste and grey water, the document notes.
In Thiruvananthapuram, a septage treatment plant was established at the medical college hospital under AMRUT-1. Steps to extend the network of sewerage in all the wards and direct the sewage to centralised treatment facility at Muttathara have been plodding on owing to several factors.
Out of the 100 wards in the corporation, 43 wards (Blocks A to E ) are fully/partially covered with sewerage facilities. For 35 Wards (Blocks F to R), design of sewerage network was prepared earlier but needs modification in lieu of the change in demography.
