Large quantities of sludge are produced in biological wastewater treatment. Sludge has a high putrescibility and therefore has to be stabilizsed in order to enable an environmentally safe utilization or disposal. The anaerobic digestion is the standard technique to stabilize the sludge. Digestion produces biogas and reduces the amount of organic matter. The amount of excess sludge production fr...

Polyhydroxyalkanoates are known to be temporarily stored by microorganisms in activated sludge, especially in anaerobic-aerobic processes. Due to the problems resulted from the disposals of plastic wastes and excess sludge of wastewater treatment plants, the production of polyhydroxyalkanoates by treating activated sludge and determining the effect of process variables were the main issues of t...

Sewage sludge treatment has become a primary subject in wastewater treatment and energy production. This paper aims to study the feasibility of power generation by incineration from sewage sludge enriched with impurities like heavy metals. For this purpose, we chose Arak wastewater treatment plant (AWWTP) and used calorific bomb test for examination. The experimental results showed that the hea...

In the present study, two bench-scale anaerobic/ anoxic/ oxic submerged membrane bioreactors were used to study the effect of thermochemical sludge disintegration system on the excess sludge production. Among the two membrane bioreactors, one was named experimental membrane bioreactor and another one was named as control membrane bioreactor, where a part of the mixed liquor was treated with the...

A mesocosm experiment to assess the fate and effects of sewage sludge in the coastal marine environment was conducted over 4 mo during the summer of 1984 with 9 different treatments of sewage sludge and nutrient addtions. Evidence from setthng rate studes, accumulahons of carbon and pollutant organics and rahos of in the sediment indicated up to 83 O/O of the sludge particulate inputs settled t...

Excess wastewater sludge collected from the recycling stream of an activated sludge process is biomass that contains large quantities of polysaccharides and proteins. However, relevant literature indicates that the bio-conversion of wastewater sludge to hydrogen is limited and therefore not economically feasible. This work examined the anaerobic digestion of wastewater sludge using a clostridiu...

polyhydroxyalkanoates (phas) are naturally occurring polyester that can be accumulated in bacterial cells as a carbon and energy storage compound. they are metabolized by many microorganisms. these biopolymers accumulate in microbial cells under stress conditions such as limitation of nitrogen, phosphate, sulfur, oxygen, and excess carbon source. currently, phas have attracted increasing intere...

Disintegration by hydrodynamic cavitation has a positive effect on the degree and rate of sludge anaerobic digestion. By applying hydrodynamic disintegration the lysis of cells occurs in minutes instead of days. The intracellular and extracellular components are set free and are immediately available for biological degradation which leads to an improvement of the subsequent anaerobic process. H...