Biological treatment, effluents

Subpart l-Direct Discharge Point Sources that Use End-of-Pipe Biological Treatment-effluent limitations BAT and NSPS... 

Toxic pollutant effluent limitations and standards for direct discharge point sources that use end-of-pipe biological treatments—effluent limitations Maximum for any 1-day Maximum for any monthly average... 

The pretreatment processes may be most effective when applied to individual waste streams from particular processes or process steps before effluent streams are combined for biological treatment. 

The capital cost of most aqueous waste treatment operations is proportional to the total flow of wastewater, and the operating cost increases with decreasing concentration for a given mass of contaminant to be removed. Thus, if two streams require different treatment operations, it makes no sense to mix them and treat both streams in both treatment operations. This will increase both capital and operating costs. Rather, the streams should be segregated and treated separately in a distributed effluent treatment system. Indeed, effective primary treatment might mean that some streams do not need biological treatment at all. 

Water reuse is usually a question of the tradeoff between the costs of raw water and the costs associated with treatment for reuse and for discharge. If biological treatment is to be employed, several factors must be considered. These are an increase in concentration of organics, both degradable and nondegradable. This may have a negative effect in terms of final effluent toxicity. An increase in temperature or total dissolved soHds may adversely affect the performance of the biological process. 

A comprehensive analytical program for characterising wastewaters should be based on relevance to unit treatment process operations, the poUutant or pollutants to be removed ia each, and effluent quality constraints. The qualitative and quantitative characteristics of waste streams to be treated not only serve as a basis for sising system processes within the facility, but also iadicate streams having refractory constituents, potential toxicants, or biostats. Such streams are not amenable to effective biological treatment, as iadicated by the characterization results, and requite treatment usiag alternative processes. 

Process industry Effluent guidelines and standards Reference Parameters regulated N eutralization Sedimentation and/or filtration Biological treatment... 

Points of Chemical Addition In independent physical-chemical treatment or in phosphate removal in the primary clarifier ahead of biological treatment, chemicals are added to raw sewage. In tertiary treatment for phosphate removal and suspended solids (SS) reduction, they are added to secondary effluent. In both cases, proper mixing and flocculation units are needed. For phosphate removal or improvement of SS capmre in biological secondary treatment, chemicals are often added directly to aeration units or prior to secondary settling units, without separate mixing and flocculation. In some phosphate removal applications coagulants are added at... 

Temperature and Humidity When adsorption, absorption, or condensation is employed, the lowest inlet gas temperature is desirable. Adsorbent and absorbent capacities generally increase with the decreasing gas temperature. High waste-gas temperatures may preclude the use of adsorption or condensatit)n due to the cost of chilling. Thermal and catalytic oxidation benefit from a hot effluent gas stream, as that reduces the supplementary fuel requirement. In biological treatment, a waste-gas temperature of near 37 °C is ideal. 

Manttari M, Nystron M (2007) Membrane filtration for tertiary treatment of biologically treated effluents from the pulp and paper industry. Water Sci Technol 55(6) 99-107... 

The advantage of ex situ biological treatment is the ability to control the effluent quality. The use of air for aerobic treatment is easier to control and costs less. Nutrient can be added more effectively and the temperature can be controlled. 

Efficiencies for removal in the wastewater treatment plant were estimated for total and soluble BOD, total COD, soluble COD, color, total suspended and dissolved solids, and total solids. The removal efficiencies summarized in Table 21.14 are high for total BOD, soluble BOD, and suspended solids, at 96%, 96%, and 95%, respectively. The removal efficiencies for total and soluble COD were significantly lower at 76% and 66%, respectively. The removal efficiency for color was only about 38%. This value is typical for biological treatment of pulp and paper wastewater, and may be due, at least partially, to the formation of new colored groups when the bleach effluents are oxidized in the treatment system. 

Tezel, U., Guven, E., Erguder, T.H., and Demirer, G.N., Sequential (anaerobic/aerobic) biological treatment of Dalaman SEKA pulp and paper industry effluent, Waste Manage., 21, 717-724, 2001. 

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