This paper presents three new approaches to reduce excess sludge production in activated sludge systems: 1) modification of conventional activated sludge process with insertion of a sludge holding tank in the sludge return line; 2) chlorination of excess sludge so as to minimize excess sludge production; and 3) utilization of a metabolic uncoupler, 3, 3', 4', 5-Tetrachlorosalicylanilide (TCS) t...

Antisera were raised against nine strains which had been isolated from phenol-acclimated oil refinery activated sludge. Although several antisera reacted significantly with the activated sludge during a period of adaptation to phenol, only an antiserum against one of the isolates, Alcaligenes sp. E2, reacted with the activated sludge after the adaptation period. A kinetic pattern of phenol-oxyg...

Palmitic acid was the main long chain fatty acids (LCFA) that accumulated onto the anaerobic sludge when oleic acid was fed to an EGSB reactor. The conversion between oleic and palmitic acid was linked to the biological activity. When palmitic acid was fed to an EGSB reactor it represented also the main LCFA that accumulated onto the sludge. The way of palmitic acid accumulation was different i...

This study aims at evaluating the impacts of PAM addition on activated sludge performance. Four lab-scale sequencing batch reactors (SBRs), each with a working volume of 3L, were investigated with different PAM concentrations. Experiments were conducted with varying organic loading rate and the sludge volume index (SVI), particle size, zeta potential, specific oxygen uptake rate (SOUR), mixed l...

The objective of this work was to verify the effect of frequent sludge soil amendments on the soil’s activity and microbial biomass C. Results showed that the use of excessive sludge doses could be detrimental to the soil’s microflora.

Morphological changes in anaerobic granular sludge fed with increasing loads of oleic acid were quantified by image analysis. The combination of this technique with data on the accumulation of adsorbed long chain fatty acid and with the molecular characterization of microbial community gave insight into the mechanisms of sludge disintegration, flotation and washout. It was found that the bacter...

the present work has been performed to eliminate sewage dry sludge of alborze city wastewater treatment plant by using them as fine aggregate in concrete. on this basis, at first the selected dry sludge was analyzed for xrd and xrf for crystalline phases and chemical composition, respectively. the results showed that more than 50% of the sludge is formed of sio2 and it had more than 20% organic...

Sewage sludge production increases continuously reaching almost 20% (946 700 t 1 118 795 tons of dry matters in 2007) during the (directly or after composting). The remaining 30% was incinerated (with or without household wastes) or landfilled. Nowadays, sludge reduction is a major concern. This activity has to becom be careful to the environmental impacts of sludge treatment and disposal route...

A lab-scale expanded granular sludge bed (EGSB) reactor was operated at 20°C with low strength wastewater (0.6-0.8 g COD/L) for over 200 days. Reactor was inoculated with mesophilic granular sludge. The up-flow velocity was set to 5 m/h by effluent recirculation. The COD loading was increased up to 12 kg COD/m3/day until the day 76, resulting in hydraulic retention time of 1.5 hours. Physical p...

Inhibition of the respiration microbial activity in the activated sludge caused by heavy metal concentrations (Cr, Cd, Cu and Ni) was studied by means of respirometric method using Strathtox respirometer (Strathkelvin Glasgow).The studied sludge samples were obtained from the two waste water treatment plants with different types of pollution (municipal waste water and domestic waste water). Key...