ACTIVATED sludge processes are the dominating wastewater treatment method. Large quantities of hazardous excess sludge are generated in the processes, and elimination of the waste sludge has been a major problem for the last decade worldwide. The disposal of waste sludge is subject to various environmental, social and economic problems; and the cost consists about 50% of the operational cost of...

This work examined how adding one of three polyelectrolyte flocculants (T3052: cationic, T2000: non-ionic, and T1052: anionic) affected the anaerobic digestion of wastewater sludge. Methane production, floc characteristics (morphology and zeta-potential) and process parameters (soluble chemical oxygen demands (SCODs) and reductive potentials) were monitored along the digestion tests. The digest...

Quorum sensing is a concentration-sensing mechanism that plays a vital role in sludge granulation. In this study, the regularities of distribution of different signal molecules, including intra- and interspecific signal molecules (diffusible signal factor, DSF), interspecific signal molecules (autoinducter-2, AI-2) and intraspecific signal molecules (acyl-homoserine lactones, AHLs), from three ...

High-throughput genomic approaches to gene function or target identification have led to the development and implementation of the 96-well format for many standard molecular biology manipulations. The apparatus described here, a Multichannel Plating Unit, is designed to plate out individual cultures efficientlyfrom standard 96-well culture blocks. Following transformation, aliquots of culture a...

Globally, wastewater treatment plants are under pressure to handle high concentration sludge in a sludge treatment line. Unawareness of the non-Newtonian behaviour of the thickened sludge has the potential to cause unexpected problems when the fluid behaviour changes from turbulent to laminar flow. In this study, sludge apparent viscosity was plotted as a function of total suspended solids conc...

Sewage sludge is an unavoidable secondary pollution produced in the process of sewage treatment. At present traditional methods of treating sludge (e.g. landfill, incineration or land application) have some disadvantages and shortages. Direct thermochemical liquefaction of sludge is a new treatment method, which has the advantage of both treatment and energy recovery. Research progress and appl...

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...

An acidophilic, sulfur-oxidizing Acidithiobacillus thiooxidans MET bacterium was isolated from anaerobically digested, dewatered sewage sludge. This bacterium showed sulfur-oxidizing ability at both acidic and neutral conditions, and allowed metal leaching even at a high (130 g L(-1)) sludge solids concentration. We found that low metal leaching efficiency at high solids concentration was mainl...

Effects of different pretreatment methods on sludge dewaterability and polycyclic aromatic hydrocarbons (PAHs) degradation during petrochemical sludge anaerobic digestion were studied. Results showed that the total biogas production volume in the thermal pretreatment system was 4 and 5 times higher than that in the ultrasound pretreatment and in the control system, and the corresponding volatil...

Sludge drying reed beds have been used for dewatering and mineralization of sludge since the beginning of the 90’s, but their insufficient performances in terms of Dry Matter [DM] content and mineralization of the sludge have made necessary new studies. Therefore, 8 pilots of 2m2 each and a full-scale plant (13 000 p.e , 8 beds of 470m2 in operation for 4 years) have been monitored to examine t...