Dissertation > Excellent graduate degree dissertation topics show

Isolation of Denitrification and Phosphorus Removal Bacterium and Its Nitrogen and Phosphorus Removing Characteristics

Author: WuShouZhong
Tutor: CaiTianMing
School: Nanjing Agricultural College
Course: Environmental Engineering
Keywords: DPAOs Growth Characteristics Nitrogen and phosphorus removing SBR System
CLC: X703
Type: Master's thesis
Year: 2010
Downloads: 17
Quote: 0
Read: Download Dissertation

Abstract

Denitrifying polyphosphate-accumulating organisms (DPAOs) used the energy generated by the degradation of PHB to storage the polyphosphates generated by the excess poly-PO43- phosphate in the body in the anoxic conditions, with the electron acceptor of oxidizing PHB was NO3- rather than O2. DPAOs could absorb phosphorus in the anoxic conditions.which made the nitrogen and phosphorus removing completed with the same strain and the same condition.The denitrifying polyphosphate-accumulating organisms (DPAOs) strain C18 was successfully isolated from the aerobic activated sludge in a municipal sewage treatment plan. On the basis of its morphological, physiological and chernotaxonomic characteristics, together with 16Sr RNA analysis, the strain was identified as Pseudomonas sp. generally.The strain C18 could utilize glucose and maltose better of carbon source. It could utilize yeast extract and peptone better of nitrogen source. The strain C18 could grow well in LB, YG medium and synthetic waste water. The optimum concentration of NaCl was 5g·L-1The optimum temperature was 30℃, the phosphorus and ammonia nitrogen removing rate could reach 90% under this temperature. The optimum pH was 7.0. The growth of the strain was inhibited when below 6.0 or higher than 8.5, and the efficiency of nitrogen and phosphorus removing was also very low. Different carbon sources had great impact on the strain removing nitrogen and phosphorus. The efficiency of nitrogen and phosphorus removing was higer when using sodium acetate and glucose as the carbon source.When the strain C18 was added in the SBR stsyem, the pH of water had a great impact on the operation, and the optimal pH range was between 7.0 to 7.5, More phosphorus would be released in the anaerobic conditions under the condition of initial pH 7.0. The HRT of the anaerobic conditions yielded a critical impact on the efficiency of phosphorus removing in the SBR system. The shorter HRT of the anaerobic conditions would reduce the efficiency, and when the HRT was too long, the phosphorus would be released ineffectively, which could cause more phosphorus releasing, but this result had no impact on the efficiency of removing phosphorus. The optimun HRT for the SBR stsyem was 2 hours for anaerobic and 4 hours for anoxic respectively. When the SRT was 10 days, the MLVSS and sludge were stable.

Related Dissertations

CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
© 2012 www.DissertationTopic.Net Mobile