Dynamics of Intracellular Polymers in Enhanced Biological Phosphorus Removal Processes under Different Organic Carbon Concentrations

Lizhen Xing,Li Ren,Yuntao Guan,Bo Tang,Guangxue Wu

doi:10.1155/2013/761082

Abstract

Enhanced biological phosphorus removal (EBPR) may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs) in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

Highlights

Eutrophication means the overgrowth of algae and cyanobacteria, and, after their death, it causes water pollution by the depletion of oxygen and the release of toxins
Total carbohydrate of biomass was measured according to Lanham et al [16]: (a) 2 mL of mixed liquor sample was added into a glass tube with 1 mL of deionized water and 0.3 mL of 6 M HCl and mixed; (b) the mixer was digested at 100∘C for 2 h; (c) after cooling down to room temperature, the digested liquor was centrifuged at 12000 rpm for 2 min, and the supernatant was taken for the measurement of glucose by high-pressure liquid chromatography (HPLC)
In spite of the relatively high effluent PO43−-P concentrations in both reactors, which could be due to the high influent PO43−-P concentration applied, a high phosphorus content in the biomass was obtained for both reactors

Summary

Introduction

Eutrophication means the overgrowth of algae and cyanobacteria, and, after their death, it causes water pollution by the depletion of oxygen and the release of toxins. Phosphorus in discharged wastewater is one of the main elements contributing to eutrophication and the worsening water quality. In order to reduce or control eutrophication of water bodies, enhanced biological phosphorus removal (EBPR) has been applied widely for phosphorus removal from wastewaters [1]. In EBPR, alternative anaerobic and aerobic phases are adopted and polyphosphate accumulating organisms (PAOs) with excess phosphorus accumulation ability will be enriched [1]. PAOs take up organic carbons such as acetate and propionate and store them as intracellular polymers such as poly-β-hydroxybutyrate (PHB), with polyphosphate as the energy source and glycogen as the reducing power source [1]. PAOs synthesize new organisms, restore polyphosphate, and replenish glycogen with stored PHB as the energy and organic carbon sources [1]. Phosphorus will be removed from wastewater by removing residue activated sludge with high phosphorus content from the wastewater treatment system

Methods

Results

Conclusion