Removal of High BOD and COD Loadings of Primary Liquid Waste Products From Dairy Industry by Vermi-filtration Technology Using Earthworms

摘要

Dairy industry generate large amount of white highly turbid liquid waste products which cannot be processed further in the industry and has to be discarded. They contain very high organic matter that may be in dissolved or colloidal form and is thus very high in BOD and total solids. Earthworms have been found to remove the 5 day BOD (BOD_5) by over 98 %, COD by 80-90 %, total dissolved solids (TDS) by 90-92 % and the total suspended solids (TSS) by 90-95 % from any liquid waste by the general mechanism of 'ingestion' and 'biodegradation' of organic wastes, heavy metals and solids. Earthworms increase the hydraulic conductivity and natural aeration by granulating the clay particles. They also grind the silt and sand particles, increasing the total specific surface area, which enhances the ability to 'adsorb' the organics and inorganic from the liquid waste. Intensification of soil processes and aeration by the earthworms enable the soil stabilization and filtration system to become effective and smaller in size. Suspended solids are trapped on top of the vermifilter and processed by earthworms and fed to the soil microbes immobilized in the vermifilter. There is no sludge formation in the process and is also odor-free. The resulting vermi-filtered liquid is clean and clear like water to be reused for irrigation.