Turbidity in Combined Sewer Sewage: An Identification of Stormwater Detention Tanks.

Yang Liu,Wei Bian,Jun Li,Liangang Hou,Dongbo Liang,Banglei Zhou

doi:10.3390/ijerph17093053

Abstract

Combined sewer overflow remains a major threat to surface water quality. A stormwater detention tank is an effective facility to control combined sewer overflow. In this study, a new method for the selective collection of combined sewer sewage during wet weather based on real-time turbidity control is established to reduce the load of pollutants entering a river using a stormwater detention tank with a limited volume. There was a good correlation found between turbidity and the concentrations of total suspended solids (TSS) (R2 = 0.864, p < 0.05), total phosphorus (TP) (R2 = 0.661, p < 0.01), and chemical oxygen demand (COD) (R2 = 0.619, p < 0.01). This study shows that turbidity can be used to indicate the concentration of TSS, TP, and COD in the sewage of the combined sewer systems in wet weather. Based on the adopted first flush detection approach, total nitrogen (TN) and TP showed the first flush effect, whereas the first flush effect of TSS and COD was not obvious. The results show that it is impossible to effectively control combined sewer overflow by only treating the initial rainwater.

Highlights

In many large cities all over the world, the combined sewer system is mostly used in old urban areas to receive rainwater runoff, domestic sewage, and industrial wastewater and is a common method of wastewater transportation [1]
The ammonium nitrogen in the combined sewer sewage in wet weather accounted for 76.5–93.2% of the total nitrogen
The average concentrations of NH4 + -N, total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), and total suspended solids (TSS) pollutants in the 21 rainfall events were 15.50, 20.69, 3.25, 142.3, and 313.3 mg/L, respectively, which are higher than the concentration limits of class V water bodies in the “Environmental quality standards for surface water” (GB3838-2002)

Summary

Introduction

In many large cities all over the world, the combined sewer system is mostly used in old urban areas to receive rainwater runoff, domestic sewage, and industrial wastewater and is a common method of wastewater transportation [1]. Under sufficient rainfall, combined sewer overflow (CSO). In CSO events, the discharge of untreated domestic sewage and rainwater into surface water means that numerous nutrients, suspended solids, heavy metals, and pathogenic microorganisms are imported. This phenomenon has become one of the main causes of pollution for many receiving water bodies around the world [5,6,7]. The construction of stormwater detention tanks is considered to be an effective measure to reduce the negative impact of CSO [8,9]

Objectives

Methods

Results

Conclusion