Abstract
Organic substances contained in 4, 000 kg of blue mussels were subjected to microbial degradation. Seawater (1, 280 L) trapped in the shells was discharged by smashing shells, and the value of chemical oxygen demand (COD) was 5, 800 mg/L. The remaining solid organic substances (2, 720 kg) including broken shells were washed with 6, 000L of tap water to reduce NaCl concentration. The COD in the wastewater was 550mg/L. The washed organic substances were subjected to compression treatment by using the Screw-press machine so as to adjust its water content (around 30%) to that optimal for microbial activity, thereby removing 680L (COD=11, 800mg/L) of wastewater from solid organic substances. Wastewater obtained at each process was collected together in one pot, and flocculating agents were added thereto to cause aggregation and precipitation, thereby recovering organic substances in the form of sludge. Water content of sludge after the belt press process was reduced from 56% to 39%, by vacuum drying. The solid organic substances obtained after washing and compressing and the sludge after vacuum drying were subjected to the degradation (45 h) by Bacillus sp. HR6. As a result, 41% (w/w) of the solid organic substances and 20% (w/w) of sludge disappeared. Total carbon and nitrogen ratios were reduced from 6.0 to 5.1 in the solid organic substances and from 12.8 to 12.5 in the sludge, respectively.
