HIGH-CONCENTRATION ORGANIC WASTEWATER TREATMENT USING INCLUSIVELY IMMOBILIZED SOIL BACTERIA

抄録

 Activated sludge method is a wastewater treatment technique used for removing organic matter from sewage using biological floc. It is a widely used low-cost and environmentally friendly method for sewage treatment. However, this method is not suitable for treating high-concentration wastewater since it is often necessary to perform physicochemical pretreatment, such as dilution with water, pressure floatation treatment, or chemical treatment. This study aims to biologically treat high-concentration wastewater using a suitably selected soil bacteria. The soil bacteria adopted in this study were separated and cultured from the soil collected in Okinawa Prefecture in 2012. The base sequence was then determined, and the homology search was performed by the Basic Local Alignment Search Tool of the DNA Data Base of Japan. It was found to be a soil bacterium called Agrobacterium Tumefaciens by 99% homology. When Agrobacterium Tumefaciens was directly used to treat high-concentration wastewater, it caused sludge bulking, and its treatment capacity was low and the chemical oxygen demand value found using chemiluminescence detection of permanganate index (CODMn) was unstable. However, there was no outflow of bacteria from the inside of the inclusion when Agrobacterium Tumefaciens were inclusively immobilized by the sodium alginate-acrylamide method, which suggested that the sludge volume could be reduced. The CODMn concentration of the artificial sewage added was 1500 mg/L, which was exponentially attenuated, and a high removal rate of 96% was observed 12 hours after the start of treatment. Furthermore, the allowable design value for the volumetric load is 3CODMn-kg/m³ per day, and thus the compactification of wastewater treatment facility should be possible. These findings have proved the significance of the treatment method proposed in this article in the field of excluded facilities for the purpose of high-concentration wastewater treatment owing to its cost reduction and downscaled treatment facility advantages.