High performance achieved by microbes to separate laundry effluents resulting in producing high water quality in a compact area

Chemical treatment enhanced with air-flotation can produce acceptable water quality for laundry effluents in a compact area. However, the stringent discharge limit of chemical oxygen demand (COD) level for direct discharge into surface water was always beyond the scope of this separation. By undertaking biological treatment before chemical separation, the amount of sludge generated from flotation resulted in a reduction of 35% for a daily flow of 100 m3. COD levels can be reduced to meet the stringent local requirement to less than 80 mg/L. Bacteria play a major role as a primary degrader to reduce pollutant, dye and toxicant in terms of COD from the effluent even at a dissolved oxygen (DO) level below 2 mg/L during the operation time. The higher trophic level microbes such as flagellate, ciliate, rotifer, vorticella and nematode were successfully introduced from a sewage treatment plant (STP) to recycle the laundry effluent. Biological recycling of the pollutants from the trade effluents was cost effective and environmentally friendly by converting them into biomass derived from the microbes. Furthermore, the very clear water produced with a low COD level from the treated effluents can be utilized for various applications such as flushing, floor washing, plantations or others.

► Pollutants in laundry effluents generate environmental and health problem to us.
► High water quality produced after treatment protects our environment and health.
► Achievement of stringent COD level is always beyond the scope of chemical treatment.
► In terms of COD, stringent water quality can be achieved by appropriate technologies.
► Microbes solve the COD problem for chemical treatment in a compact area.