Studies On Photosynthetic Bacteria Biomass Separationand Brewery Wastewater Reclamation

Since 60's in 20th century, photosynthetic bacteria (PSB) was gradually promote into application in the fields of wastewater treatment and reclamation due to its high efficiency, low energy consumption and less sludge disposure in high concentrated organic wastewater treatment process, and its capable of producing high-value nutrients in biomass. Biomass should be separated between wastewater treatment and utilization processes. However, the research about biomass separation was rarely. This study used a strain of Rhodobacter Sphaeroides, which was isolated from soil in previous research and named Z08. Different separation methods were studied and the most effective one was optimized in order to achieve an efficient way to gain pure PSB biomass. The effluent from PSB separation process could reach the standard for discharge or go through post-treatment process. The biomass could be reclaimed to realize resource reuse. The study also discussed about PSB brewed wastewater treatment base on the optimized separation method.Immobilization, coagulation and ultra-filtration were studied to separation PSB. The result showed that immobilization could hardly immobilize PSB on all the supporters. Coagulation could achieve 51%-92% separation ratio. However it consumed about 1000-5000 mg/L coagulant. The dosage was to much for application and could pollute the biomass after separation process. Ultra-filtration could achieve desired separation ratio, average 99%, and could avoid the pollution in biomass separation process.When the biomass was 840 mg/L, the optimized pressure was 0.02 MPa, back-washing time was 24 h, influent rate was 55 L/h and average flux was 16 L/m2h. The back-washing was operated under 0.2 MPa, with influent rate 55 L/h for 5 min. In 24 h separation, 58.78 L water and 50000 mg biomass were separated. The separated water was used for back-washing, and the water used in back-washing process was 5 L. The water production was much more than back-washing consumption. Which meant the ultra-filtration system was self-sufficiency without extra water supply. The initial COD in brewed wastewater was 3000-5000 mg/L in this study. PSB brewed wastewater treatment was operated under the environmental condition as following: anaerobic condition in day-time, aerobic condition in dark-time. The F/M was 2, HRT was 72 h. After treatment, the COD removal rate was 91%, and the biomass production was 39%. PSB was separated by ultra-filtration membrane due to its disadvantage of sediment difficulty. The new born biomass was reclaimed for other utilization, and extra biomass was pumped back to the bio-reactor.