Wastewater biological treatment processes

Secondary Treatment A wastewater treatment process used to convert dissolved or suspended materials into a form more readily separated from the water being treated. Usually the process follows primary treatment by sedimentation. The process commonly is a type of biological treatment process followed by secondary clarifiers that allow the solids to settle out from the water being treated. Sedimentation The process of subsidence and deposition of suspended matter from a wastewater by gravity. 

Biological Treatment Processes for Urea and Formaldehyde Containing Wastewater... 

The deep shaft biological treatment process,87 which is one of the activated sludge systems, has been successfully applied to a paper mill wastewater treatment in Japan (see Case Study III, Section 21.6.3). 

The biological treatment process involves the use of microorganisms such as bacteria and fungi to convert finely divided colloidal and dissolved carbonaceous organic matter in wastewater into various gases and into cell tissues that are then removed from sedimentation tanks as flocculent settle-able organic and inorganic solids. This process often complements both physical and chemical processes and it is classified as follows. 

Dos Santos AB, Bisschops LAE, Cervantes FJ (2006) Closing process water cycles and product recovery in textile industry perspective for biological treatment. In Cervantes FJ, Van Haandel AC, Pavlostathis SG (eds) Advanced biological treatment processes for industrial wastewaters, vol 1. International Water Association, London, pp 298-320... 

Biological toxicity tests are widely used for evaluating the toxicants contained in the waste. Most toxicity bioassays have been developed for liquid waste. Applications of bioassays in wastewater treatment plants fall into four categories [19]. The first category involves the use of bioassays to monitor the toxicity of wastewaters at various points in the collection system, the major goal being the protection of biological treatment processes from toxicant action. 

Activated sludge is the most common biological treatment process because of the high rate and degree of organic stabilization possible. It is widely used in treating refinery wastewater [5]. 

Despite the initial apprehension over the possible extent of impacts of surfactants on the physicochemical or biological treatment processes of municipal and industrial wastewaters, it soon became evident that no major interference occurred. As mentioned previously, the greatest problem proved to be the layers of foam that not only hindered normal sewage plant operation, but when wind-blown into urban areas, also aided the probable transmission of fecal pathogens present in sewage. 

Hall, E.R. Randle, W.G. AOX removal from bleached Kraft mill wastewater. A comparison of three biological treatment processes. Water Set Technol. 1992, 26 (1-2), 387-396. 

Aerobic biological treatment process for domestic or industrial wastewaters. Treated water from this process can often be used as a low cost makeup water source for cooling towers. 

The aerobic complete-mix biological treatment process without recycle, as shown in the drawing, receives wastewater with a biodegradable soluble COD (bsCOD) concentration of 500 g/m3. The flowrate is 1000 m3/d and the reactor effluent bsCOD and suspended volatile solids (VSS) concentrations are 10 and 200 g/m3, respectively. Based on these data ... 

Describe the various biological treatment processes employed for wastewater. 

These nutrients are important in natural waters because, in excess, they can cause nuisance growth of algae or aquatic weeds. In wastewater treatment, a deficiency of nutrients can limit the effectiveness of biological treatment processes. In some plants treating industrial wastewaters, ammonia or phosphoric acid must be added as a supplement. 

Industrial wastewaters are often mineralized to a high degree due to the high concentration of chlorides, sulphates and other salts — sodium, potassium or calcium ones, the concentration of which can be as much as tens of g 1. Concentrations of ions (e.g. Na , Cl, SO ) higher than 10 g 1 can negatively influence biological treatment processes of these waters. Such salts are introduced into wastewaters particularly from neutralization and salting out of different products, or from neutralization of acid or alkaline wastewaters. 

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