Effluent discharge standards

Depending on the state where the industrial plant is located, an aqueous effluent from a pretreatment facility or a complete end-of-pipe treatment facility can be discharged into a river, a lake, or an ocean, only if it meets the pretreatment standards and the effluent discharge standards established by the regulatory agencies, in accordance with the National Pollutant Discharge Elimination System (NPDES) or the State Pollutant Discharge Elimination System (SPDES). The standards can be industry-specific, chemical-specific, or site-specific, or all three. The readers are referred to other chapters of this handbook series for the details. 

Degree of Treatment The desired or required degree of treatment depends on objectives. It may meet the effluent discharge standards, or the requirements for water reuse, or the quantity/quality of recovered material. 

UF is used to treat wastewater to meet the municipal effluent discharge standards and to recover valuable component for recycle as in the case of oily wastewater. The sources of oily wastewater include metal works, textile industries, automotive, aeronautical and animal/vegetable fats industries and industrial laundromats. Hydrophilic UF membranes (e.g., polyacrylonitrile and PES) are used for recovering oil from oily waste waters instead of hydrophobic membranes (e.g., PVDF) that get fouled with oil resulting in loss of flux. The oil droplets are completely retained by the UF membrane, although the membrane is... 

Liquid effluents are similarly required to meet local standards and in this case due to the relative insolubility of lead it is often associated metals that require closest attention. Liquid effluents are commonly processed by lime neutralisation to precipitate metals, aiming for pH levels of the order of nine to ten. Typical effluent discharge standards are given in Table 15.7. 

Kowalchuck (2011) selectively removed F from drinking water based on a process which combined precipitation by aluminum hydroxide Al(OH)3 with subsequent removal of the floe by membrane ultrafiltration. A 0.3 gal min ( 11.4 Lmin ) pilot test plant achieved F removal to a concentration of 3.5 mg L at an aluminum dose of 30 mg L . The former F concentration met the USEPA effluent discharge standard of 4 mg L for F from wastewater. However, it was not in the optimum range since the maximum WHO safe F level in drinking water is considered to be between 0.5 and l.OmgL (Ghorai and Pantk, 2005 Wang and Reardon, 2001 WHO, 2011). 

Industrial wastewater Process effluent treatment to meet environmental discharge standards Reduction of total organic halogens (TOX), biological oxygen demand (BOD), and chemical oxygen demand (COD)... 

Municipal sewage-treatment effluents discharge to surface waters and is subject to the same EPA control on quality and quantity as independent industrial surface-water discharges. Any tightening of EPA standards may therefore result in more stringent controls on industrial effluents discharged to sewers. All the water companies levy charges on industry for the reception, conveyance and treatment of the industrial effluents. 

Direct discharges are discharges from point sources into surface water pursuant to a National Pollutant Discharge Elimination System (NPDES) permit. NPDES permits are granted on a case-by-case basis and limit the permissible concentration of toxic constituents or conventional pollutants in effluents discharged to a waterway. These limits are generally established on the basis of the best available treatment technology and, where necessary, to protect surface water quality standards. 

As was indicated in the previous section, the concentration of iron in the mixed wastewaters ranged from 5980 to 6100 mg/L its pH was 0.7 and zinc concentration was 15 pg/L. Since these wastewaters come only from acid baths and not from other processes of the plant, parameters such as cadmium and fluoride are not encountered. The discharge standards for the metal industry effluents set by the Turkish Water Pollution Control Regulation (Official Gazette, Table 15.7, September 4, 1988) are shown in Table 28.10.1... 

Skim tanks. Tanks have been used for many years as oil field oil/water separators, or water polishers in high rate, high water-cut service. They are nothing more than cylindrical separators, lubricated from standard tank which have a central entrance and a peripheral effluent discharge. 

Another example of using ultrafiltration for wastewater treatment and resource recovery is the separation of oil-water emulsions generated from metal machining, oil field wastes, and enhanced oil recovery effluents. Hydrophilic membranes such as cellulose acetate are preferred because they are effective barriers to oil droplets and are less prone to fouling. The UF permeate readily meets direct discharge standards. The oil-rich stream can be processed to reclaim the oil, or disposed at reduced transportation cost because of its reduced volume. 

TABLE 26. Discharge Standards for Palm Oil Industrial Effluents for Malaysia. 

Mainly the effluent treatment units only, with emphasis to check if they are meeting the required discharge standards. 

All permit effluent limitations, standards, and prohibitions, including those necessary to achieve water quality standards, will be stated as maximum daily and average monthly discharge limitations for all dischargers. 

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