Feasibility and optimization of wastewater treatment by chemically enhanced primary treatment (CEPT): a case study of Huangshi

Qiulai He,Hongyu Wang,Congyuan Xu,Jing Zhang,Wei Zhang,Zhuocheng Zou,Kai Yang

doi:10.1080/09542299.2016.1247657

Abstract

Carbon and nutrients as well as suspended solids (SS) removal by chemically enhanced primary treatment (CEPT) were conducted in the Qingshan wastewater treatment plant in Huangshi, Hubei Province. Feasibility of this process for wastewater treatment were investigated in detail by comparing the removal performance of three inorganic chemical coagulants (polyaluminium chloride, polyaluminium ferric chloride [PAFC] and poly ferric sulfate) individual or couple with poly acrylamide, optimizing the conditions during CEPT by both single factor analysis and orthogonal test designs. The results of this study demonstrated that CEPT turned out to be an effective method for wastewater treatment, with PAFC as the optimal coagulant, which showed preeminent removal capacity for chemical oxygen demand, total phosphorus and SS. The optimal working condition could be at pH 7.0, settling time 15 min, and velocity gradient of 174.80 and 15.56 s−1 for mixing and reaction phase respectively. While the coagulant dosage depends on raw water attributes, which had a decisive effect on CEPT treatment performances. However, the three coagulants behaved poorly in nitrogen removal.

Highlights

Enhanced primary treatment (CEPT), or advanced primary treatment (APT) refers to the process which applies chemicals, typically metal salts and polymers in the form of organic polyelectrolytes, for coagulation, flocculation and precipitation of particulate/dissolved solids.[1]
The experimental plant is located in the Qingshan Lake wastewater treatment plants (WWTP) (Huangshi, Hubei Province), of which the influent is dominant by domestic wastewater
chemical oxygen demand (COD) removal COD removal performance by individual chemical coagulant and couple with PAM at various dosages was present in Figure 1(A) and (B), respectively

Summary

Introduction

Enhanced primary treatment (CEPT), or advanced primary treatment (APT) refers to the process which applies chemicals, typically metal salts and polymers in the form of organic polyelectrolytes, for coagulation, flocculation and precipitation of particulate/dissolved solids.[1] The suspended particles clump together through the processes of coagulation and flocculation. The particles aggregates, or flocs, settle faster, enhancing treatment efficiency.[2]. CEPT technology has been used at various wastewater treatment plants (WWTP), targeting at clarification of wastewater, phosphate removal, reduction in sludge volume, and increase in surface overflow rates.[1,3] Apart from carbon and nutrients, CEPT can remove other contaminants, such as heavy metals,[4] polycyclic aromatic hydrocarbons (PAHs) [5] and helminth eggs [6] associated with particles. The related parameters during this process depend on the primary objective of application

Objectives

Methods

Results

Conclusion