Discharge limitations

The Clean Water Act (1972) requires discharge limits to be set on industrial and municipal wastewater, and these analyses are outlined in the National Pollution Discharge Elimination System for the 600 Series Methods. Method 624 covers the analysis of purgeable organic compounds Method 625 covers the analysis of 81 bases, neutrals, and acids Method 613 describes the analysis of dioxins and furans. 

NO Abatement. Source performance standards for nitric acid plants in the United States were introduced by the U.S. EPA in 1971 (55). These imposed a discharge limit of 1.5 kg of NO as equivalent nitrogen dioxide per 1000 kg of contained nitric acid, which corresponds to about 200—230... 

The Clean Water Act strives to restore and maintain the chemical, physical, and biological integrity of the nation s water. The act sets up a system of water quality standards, discharge limitations, and permits. If a project may result in the... 

Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program - Volume 1, November 1987 ERIC W025 NTIS PB95-157707. 

This concentration should be compared against permissible exposure limits estabhshed by OSHA (Occupational Safety and Health Act) and allowable discharges limits set by federal (EPA) and local emissions regulations. 

As already mentioned, the scope for direct disposal to drain can be limited by local regulations and will often involve costs. Whilst this may be an option at present, it will become less attractive in the future as discharge limits are tightened. 

The effluent discharge limitations imposed by the Federal and local governments... 

The type of vapor treatment that is used will depend on factors such as the contaminant concentrations in the extracted vapors and the air emission discharge limitations for the site. Highly contaminated vapors at a site with stringent air emission limitations may require a multistep vapor treatment train, such as thermal oxidation, followed by carbon adsorption. Less contaminated vapors at a site with less stringent air emission limitation may require minimal or no vapor treatment. Fields et al.38 described the following rules of thumb for selecting vapor treatment ... 

A philosophy of design is required that will allow the designer to combine effluents for treatment when it is appropriate, but also segregate them if it is appropriate. Consider now the targeting of minimum treatment flowrate for a given set of effluent streams that need to be treated to bring the concentration to below an environmental discharge limit. 

Example 26.3 The data for a wastewater treatment problem are given in Table 26.8. Centralized treatment would correspond with a flowrate to be treated of 75 t-tr1. For an environmental discharge limit of 20 ppm, determine the minimum treatment flowrate. 

One complication not considered so far that is very commonly encountered in effluent systems is where some of the effluents are already below their environmental discharge limit. Table 26.9 presents a problem involving four effluent streams. The environmental discharge limit is 20 ppm. 

Table 26.9 A problem where one of the effluents is below the environmental discharge limit.

The effluent streams are currently combined and sent to a steam stripper to remove NH3 from wastewater. The environmental discharge limit for NH3 is 30 ppm. 

A water network produces the 6 effluent streams in Table 26.17. The environmental discharge limit for the contaminant concentration is 50 ppm. There are two treatment processes available on the site, which are capable of reducing... 

The environmental discharge limit for the contaminant is 50 ppm. Freshwater is available with a concentration of 0 ppm. A treatment process is available capable of achieving a contaminant outlet concentration of 20 ppm. 

Phenols are carcinogenic [39-42] and mutagenic thus affect the central nervous system. Long term contact to phenol may even paralyze the body and damage liver, kidneys [41] and heart [43]. Phenol and its vapour are corrosive to the eyes, skin and respiratory tract [44], Renal failure and pulmonary toxicity has been reported with overdose of 89% injectable phenol solution [45]. According to Central Pollution Control Board (CPCB) the discharge limit of phenol in inland water should be lower than 1 mg/1 [46],... 

These synthetic pyrethroids mimic natural counterparts, of which the most important is pyrethrin 1 (10.265). Unfortunately, the natural products lack the photochemical and hydrolytic stability necessary for use as wool insect-resist agents. The synthetic products have the required stability, yet retain the low mammalian toxicity and low environmental retention of the natural products. Permethrin, however, is toxic to aquatic life and is therefore subject to increasingly severe discharge limits. There is some evidence that permethrin is less effective against larvae of a certain beetle. This can be compensated for by using a combination of permethrin with the hexahydropyrimidine derivative 10.264. Some possible alternative pyrethroids have been mentioned [517] as development products (10.266-10.269). 

Table 3 Current national discharge limits and proposal levels for production of bleached Kraft and bleached sulphite pulp [5]... 

Environmental limits or guidelines for the pulp and paper industry vary significantly between European countries, despite efforts to create a more uniform system [5]. As an example the discharge limits for bleached Kraft and bleached sulphite pulp are given in Table 3. In some countries, such as Austria or France, there is different legislation depending on the type of paper mill. Normally, the most restrictive corresponds to the bleached Kraft pulp. In other countries, such as Ireland, there are no requirements or limits for some parameters. 

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