Abstract

Sewage treatment ultimately culminates in the concentration of the solid phase. Sludge are separated mainly in primary or secondary decanters. Even in biological treatment, where biological degradation of organic matter actually occurs, there is the separation of excess sludge concentrated in the bottom of the secondary settlers of activated sludge systems or biological filters. In fact, the production of sludge is an important differential in the choice of the treatment system. While purely aerobic systems such as activated sludge or high-rate biological filters can produce 0.6-0.8 kgSS/kgBOD applied, sludge production in an upflow anaerobic sludge blanket (UASB) reactor is only about 0.2 kgSS/kgCOD applied. Even the mixed anaerobic/aerobic system leads to less sludge production than that of an exclusively aerobic system. This advantage is very important nowadays, especially since, besides reducing the treatment needs, the difficulties with the final disposal of the sludge are usually very large.

Highlights

  • The main concern in relation to sewage treatment is to solve the problem of the liquid phase, leaving in the background the solution of the problem of the sludge generated in the treatment of this liquid phase

  • In order to study the alternatives for the treatment and disposal of sewage and the sludge generated in the treatment of the liquid phase, it is necessary to first know the possibilities of treating a sewage, in view of the quality of the final effluent to be obtained, as well as the quantities and qualities of the sludge produced in the wastewater treatment plant (WWTP), which constitutes the main objectives of this work

  • This chapter covered the classic processes applied to the treatment, digestion, and drying of sewage sludge

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Summary

Introduction

The main concern in relation to sewage treatment is to solve the problem of the liquid phase, leaving in the background the solution of the problem of the sludge generated in the treatment of this liquid phase. When there is a sewage treatment in which the generation of sludge is quite significant and the main concern with this sludge, at first, is restricted to its stabilization and dewatering to reach a solid content of the sludge in the range of 15–40%, aiming almost exclusively at its removal from the wastewater treatment plant (WWTP) area by trucks, has no clear definition of its final destination. In order to study the alternatives for the treatment and disposal of sewage and the sludge generated in the treatment of the liquid phase, it is necessary to first know the possibilities of treating a sewage, in view of the quality of the final effluent to be obtained, as well as the quantities and qualities of the sludge produced in the WWTPs, which constitutes the main objectives of this work. For the design of the new WWTPs, it is recommended that, in addition to the quality of the effluent to be required depending on the receiving body, the destination to be given to the sludge is considered, as this aspect may be preponderant for the definition of the sewage treatment system and sludge to be adopted

Sludge treatment steps
Sludge densification
Gravity density
Sludge digestion
Anaerobic sludge digestors
Sludge dehydration
Sludge drying beds
Mechanical sludge dehydration
Disinfection
Findings
Conclusion
Full Text
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