The Lachish regional council needed to treat wastewater from the eastern part of the region and decided to construct a regional wastewater treatment plant for the wastewater streams - Amatzia
The regional council needed to reach high quality, tertiary level effluent, in order to reuse the water for irrigation and adhere to the Inbar committee standards. However, the council did not want to deal with large quantities of sludge, a bi-product of all biological treatment processes.
Shtang Construction & Engineering, having won the commission from the regional council, proposed an innovative solution: a compact reactor based on MSABP (Multi - Stage Activated Biological Process). This process is based on the generation of a hierarchy of bacterial colonies and micro-organisms that in turn creates a food-chain sequence in which elite organisms feed off of inferior ones, which develop at an earlier stage of the food chain.
The bioreactor is constructed of 8 separate cells in which both aerobic and anoxic processes take place simultaneously.
Colonies develop in the various cells, on a special substrate, in controlled conditions that lead to the development of a process in which the food for a certain colony in a certain cell is the product of the biological process in the preceding cell. A steady state is reached under these controlled special conditions and the excess sludge volume is lowered by over 60% compared with the conventional activated sludge process.
The system is comprised of an automatic, 1 mm screen as pre-treatment, an equalization tank and a pumping station, the bioreactor, a secondary clarifier and a phosphorous removal system, a tertiary treatment system (sand pressure filtration), a contact tank for disinfection, a sludge treatment module (a stabilization tank and a drying field) and a computerized command & control system.
After almost two years of operation the plant has yet to produce any excess sludge and provides tertiary-level effluent