Optimization of photosynthetic bacteria wastewater treatment and study of microbial species diversity

Abstract

The photosynthetic bacteria (PSB) wastewater treatment was optimized in terms of light and oxygen conditions, pH, temperature, initial PSB, and wastewater concentrations. The changes of microbial species were studied using PCR–DGGE technique. The results showed that in batch reactors the optimum conditions of PSB soybean wastewater treatment were natural light-micro oxygen, initial PSB concentration of 160 mg/L, initial wastewater concentration of 3,600 mg/L, pH of 8.0, and temperature of 30°C. In semi-continuous reactors, the results verified that under the optimum conditions PSB soybean wastewater treatment was effective and PSB biomass increase was good. PCR–DGGE analyses showed that the types of micro-organisms in the reactor gradually increased. Under the optimum conditions, Lactococcus lactis subsp. formed on the 7^th day; Veillonella sp. and Dysgonomonas sp. formed on the 14^th day; and iron-reducing bacterium and Veillonella sp. formed and Lactococcus lactis subsp. disappeared on the 21^st day; Janthinobacterium lividum formed on the 28^th day; and the community did not change from the 28^th to 35^th day; after that the system entered a stable situation. PSB were the dominate bacteria during the whole period.

Keywords:

• PSB
• Wastewater treatment
• Natural light-micro oxygen condition
• Microbial species
• PCR–DGGE

Acknowledgments

Authors thank financial supports from National Natural Science Foundation of China (50978072, 51278489) and helpful suggestions from Professor Jianzhen Li in paper revision.