the excess sludge treatment and sludge disposal are major factors to the over-all economy of wastewater treatment plants (wwtp). the ideal solution to the problem of sludge disposal is to combine sludge minimization with contamination removal at the source. in this study, the effect of ozonation, chlorination and 3,3,4,5–tetrachlorosalicylanilide (tcs) to treat part of the return activated slud...

the excess sludge treatment and sludge disposal are major factors to the over-all economy of wastewater treatment plants (wwtp). the ideal solution to the problem of sludge disposal is to combine sludge minimization with contamination removal at the source. in this study, the effect of ozonation, chlorination and 3,3,4,5–tetrachlorosalicylanilide (tcs) to treat part of the return activated slu...

Sequencing batch reactor (SBR) systems were used for the development of a system and operating procedures for the high production and storage of polyhydroxyalkanoates (PHAs) by wastewater treatment (activated sludge) bacterial cultures. The systems were maintained at a nominal hydraulic retention time (HRT) of 10 hours, and a temperature of 20°C. The solids retention time (SRT) was maintained a...

Microbial activity measurements (oxygen transfer rate, OTR, carbon dioxide transfer rate CTR and respiratory quotient, RQ) are used to monitor and control biological processes. In this study, the digestion of activated sludge in microaerobic conditions was evaluated. The changes of biological activity during digestion were monitored by respiration activity. The sludge mixtures used were primary...

As input to the steady state design and kinetic simulation models for the activated sludge system, the correct value for the heterotroph anoxic yield is essential to provide reliable estimates for the system denitrification potential. This paper examines activated sludge anoxic yield values in the literature, and presents experimental data quantifying the value. In the literature, in terms of t...

Seeding of nitrifying bacteria into the activated sludge process was studied both theoretically and experimentally. A simple model was developed for prediction of the effects of seeding of nitrifying bacteria from a separate stage into the activated sludge process. The purpose of seeding is to improve the treatment results and the process stability as well as to decrease the volume requirements...

The activated sludge biodegradability of 12 commercial phthalate esters was evaluated in two test systems: (i) a semicontinuous activated sludge test and (ii) an acclimated 19-day die-away procedure. Both procedures demonstrated that phthalate esters are rapidly biodegraded under activated sludge conditions when loss of the parent phthalate ester (primary degradation) is measured.

Activated sludge gains xenobiotic degradation capability through acclimation to the target. Acclimated activated sludge contains a two-part biomass of non-degrader and degrader, abundance of the latter being most important for activated sludge to successfully treat the inflow of xenobiotic pollutants. For the purposes of understanding and also possible improvement of xenobiotic treatment, xenob...

A membrane-coupled aerobic bioreactor (MBR) can be described as a system coupling the aerobic bioreactor, or activated sludge tank, of a wastewater treatment system with a microor ultrafiltration membrane. The membrane serves to separate the suspended material in the sludge so that the permeate stream is free of chemicals, microorganisms, and other contaminants. The membrane may be either inter...

PHYSICAL, chemical, and biological properties of activated sludge are influenced by changes in ionic strength and ionic composition of sludge. Many studies have investigated the effects of various cations on sludge characteristics [e.g. 1–6] and concluded that cations, particularly divalent cations, play a crucial role in the formation of flocs, influence floc properties such as size, density, ...