Performance of Denitrifying Phosphate Removal via Nitrite from Slaughterhouse Wastewater Treatment at Low Temperature

Min Pan,Guangxue Wu,Yuansheng Hu,Xiaoming Huang,Yan Yang,Xinmin Zhan

doi:10.3390/w9110818

Abstract

This study aims to investigate the effects of the organic loading rate (OLR) and the aeration rate on denitrifying phosphate removal (DPR) from slaughterhouse wastewater treated at a temperature of 11 °C. Three laboratory-scale intermittently aerated sequencing batch reactors (IASBRs) were set up and three OLRs and five aeration rates were employed in the study. The results indicated that efficient removals of nitrogen (N) and phosphorus (P) from DPR were achieved. Furthermore, the intermittent aeration pattern benefitted both the phosphorus-accumulating organisms (PAOs) and the denitrifying phosphorus-accumulating organisms (DPAOs) that accumulated at 11 °C. The ratio of P uptake in the aeration periods/P release in the non-aeration periods was in the range of 0.94–1.10 in the three stages. The relationship between the specific poly-β-hydroxybutyrate (PHB) degradation rate (z), the specific P removal rate (x), and the specific total oxidized nitrogen(TON) reduction rate (y) can be fitted approximately as a plane ( z = 1.3626 x + 0.2882 y − 0.6722 , R2 = 0.83).

Highlights

Eutrophication is a key driver causing numerous environmental problems, naturally controlled mainly by phosphorus and nitrogen bioavailability [1]
Hu et al [5] stated that denitrifying phosphorus-accumulating organisms (DPAOs) could be subdivided into two groups: one group
The reactors were constantly stirred during the fill, non-aeration and aeration periods, while in the aeration periods air was supplied by air diffusers located at the bottom of the reactors

Summary

Introduction

Eutrophication is a key driver causing numerous environmental problems, naturally controlled mainly by phosphorus and nitrogen bioavailability [1]. Relying on the capacity of denitrifying phosphorus-accumulating organisms (DPAOs), P removal is encouraged to mediate denitrification in the anoxic periods. Compared with the conventional enhanced biological phosphorus removal (EBPR) process, the DPR can reduce 30% of the aeration demand, 50% of the carbon source requirement, and 50% of the sludge production [3]. In a similar metabolic mechanism with the PAOs, the DPAOs utilize an external carbon source to store polyhydroxyalkanoates (PHA, including poly-β-hydroxybutyrate [PHB] and poly-β-hydroxyvalerate [PHV]) in an anaerobic period. They employ nitrite (NO2 − ) or nitrate (NO3 − ) as the electron acceptor instead of oxygen for P uptake by oxidizing intercellular PHA [4]. Hu et al [5] stated that DPAOs could be subdivided into two groups: one group

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