Quality of surface water and generation of sludge at water treatment plants

Fabiana Alves Fiore,Suzelei Rodgher,Vivian Silveira Dos Santos Bardini,Luis Miguel Gutiérrez Klinsky,Cristiane Yumi Koga Ito

doi:10.4136/ambi-agua.2565

Abstract

Among the waste produced daily by communities are those resulting from the treatment of water for public supply, with local specificities that reflect the characteristics and uses of the land. Despite the continuous generation and inadequate disposal still current in Brazil, there is little information on these residues. The data related to the composition of these sludges are essential for the study of alternatives for beneficial uses and for determining the risks to the environment and human health from inadequate disposal. It is in this context that the present study was developed, with the objective of identifying the physical-chemical characteristics of sludge produced in water treatment plants (WTPs) and of verifying the presence of these elements in the waters of the source used for supply. Such research was carried out through a case study in two WTPs in the state of São Paulo that perform surface abstraction. Therefore, in each of the WTPs, samples of densified sludge, representative of the dry and rainy periods, were characterized. The chemical findings of the sludge have been compared to the historical series of a decade of monitoring of the water quality of the sources of these WTPs. Among the main results, concentrations above the reference limits for the inert residues of aluminum, iron, manganese and barium in sludge are highlighted, as well as the existence of iron and manganese in the raw water collected and the variations in the concentrations of iron, sodium and manganese in the sludge due to the climatic conditions.

Highlights

In Brazil, the water supply is an essential service under public responsibility and aims to ensure adequate conditions of basic sanitation in the national territory
In order to accomplish the current guidelines of potability, in most of the cases water is treated in complete cycle stations that generate sludge (Brasil, 2007; 2019)
The generation of sludge in water treatment stations can be estimated by empirical formulas that are dependent on the physicochemical characteristics of water and products used in the process

Summary

Introduction

In Brazil, the water supply is an essential service under public responsibility and aims to ensure adequate conditions of basic sanitation in the national territory. In 2017, 90% of the population inhabited urban centers and the mean per capita demand of water was approximately 160 liter/day. In order to accomplish the current guidelines of potability, in most of the cases water is treated in complete cycle stations that generate sludge (Brasil, 2007; 2019). The generation of sludge in water treatment stations can be estimated by empirical formulas that are dependent on the physicochemical characteristics of water and products used in the process. Considering the generation of sludge of approximately 1 to 3% of treated water, according to Messias (2013), in Brazil the generation of sludge per day would be around 260,000 to 800,000 m3

Methods

Results

Conclusion