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...

The objective of this paper is to complement the effluent quality (EQI) and operational cost (OCI) indices used to evaluate (plant-wide) control strategies in wastewater treatment systems with a new dimension dealing with greenhouse gas (GHG) emissions. The GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site (secondary and sludge...

BACKGROUND There are more than 350 wastewater treatment plants distributed across different parts of Oman. Some of them produce large quantities of domestic sewage sludge, particularly this study focused on characterizing domestic sludge of six treatment plants that may contain various pollutants, therefore the proper management of domestic sewage sludge is essential. METHODS Samples of domes...

the activated sludge process simply involves bringing together wastewater and a mixed culture of microorganisms under aerobic conditions. the system usually includes a secondary treatment given to the settled sewage, and requires an environment in which active microorganisms are maintained in intimate contact with wastewater in the presence of sufficient oxygen. in this study, the treatment of ...

Sewage sludge is generated as a result of treating municipal wastewater to remove organic and inorganic impurities from dilute solutions. The treatment results in concentrating the impurities into a smaller volume of liquid, called sludge. The main processes involve sludge stabilisation, dewatering and incineration. The major objective of stabilisation is to make the sludge less odorous and put...

A suspension of wastewater and treatment organisms in an aerated tank is known as the activated sludge process. The activated sludge process can be used for onsite wastewater treatment, generally requiring the addition of an air pump to deliver oxygen to the system and provide mixing energy. Suspended growth treatment systems can be secondary only (require supplemental primary treatment) or com...

Wool scouring sludge is the solid waste product of anaerobic treatment of wool scouring effluent. It has a high wool grease content (1316% of the dry weight, 45 -55% of the organic matter), resulting in a low melting point (approx. 45°C). The low melting point, the putty-like physical properties and the odourous. unstable nature of the sludge makes it unsuitable for land application in its raw ...

In activated sludge systems, the sludge settling ability is considered a critical step where filamentous bulking and biomass deflocculation are the most common problems, causing the reduction of the effluent quality. Furthermore, in recent years image processing techniques have been successfully used to elucidate the activated sludge morphology. Keeping that in mind, a program was developed for...

Physicochemical studies on wastewater quality and microscopic analyses of activated sludge are necessary to properly evaluate the condition of activated sludge. The aim of this study was to evaluate the application of the sludge biotic index to determine when a change in treatment quality is short-lived, caused by, e.g., a change in influent quality or quantity, and when it indicates adverse ch...

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...