Current Technologies for Sludge Treatment and Disposal

Abstract

This paper reviews the current sludge technologies and discusses likely future trends associated with those technologies. It describes the role of thickening, dewatering, pasteurization, stabilization, thermal destruction and product enhancement to satisfy environmental standards. Reference is made to technologies which, for decades, have been associated with sewage sludge but where market conditions have forced R and D initiatives to be introduced and commercialized.

Application of flat-sheet membrane to thickening and digestion of waste activated sludge (WAS)

“…Several problems and disadvantages are still existing among the typical sludge thickening technologies, e.g., the large footprint and low thickening efficiency and the release of phosphorus under long sludge retention time (SRT) with gravity thickening process, lower quantity of sludge storage and higher energy cost with DAF thickening compared with gravity thickening, and much higher energy cost and advanced maintenance requirements with centrifugal thickening technology [3][4][5]. If sludge thickening could not perform reliably, it would lead to an increase in volume load on the sludge dewatering process, a decrease in dewatering performance and an increase in pollution load of the return flow [2,6]. In order to solve some problems with conventional sludge thickening technologies, to provide an alternate process for sludge thickening and to improve its efficiency and reliability, the flat-sheet membrane for sludge thickening (MST) process was developed in this paper.…”

Characterization of Odors from Limed Biosolids Treated with Nitrate and Anthraquinone

“…[8] Lime is added to raw sludge until the pH is >12. [8] Lime is added to raw sludge until the pH is >12.…”

Composition, Production, and Treatment of Sewage Sludge

“…In a system of conventional activated sludge or aerobic biological filters, the sludge is mixed, primary and secondary. It is generated with a solid content between 1.0 and 1.5%, and its increase to about 4% allows an even greater reduction in volume, being able to prove the advantage of incorporating it into the system, in view of the much smaller required volume of anaerobic sludge digesters [1,5,6].…”

“…Then, it is mixed with the sludge at the entrance from the bottom of the flotation chamber, with scraping removal of the densified sludge at the top and the sub-liquid to return to the entrance of the WWTP. Recently, machines for the mechanical thickening of sludge have been developed [5,7]. They are machines designed to provide only a partial dehydration of the sludge, around 4-5%, for later final dehydration that can also be mechanized.…”