Particular process effluents

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 eontrol of pH is a very important problem in maity processes, particularly in effluent wastewater treatment. The development and solution of mathematical models of these systems is, therefore, a vital part of chemical engineering dynamic modeling. 

Toxicity management of process effluents within particular industrial plants. 

Water consumption of the jets as a percentage of process effluent decreases from 5% at 15 psi to 2% at 50 psi. In general, backwash systems are operated at as low a pressure as possible consistent with successful cleaning. High-pressure operation incurs added system maintenance, particularly jet replacement, and is used only as needed. 

It is always essential to use less quantity of water with proper quality for a particular process. The cost of water is increasing and in order to conserve energy it is necessary to reduce the water consumption in the process house. This is expected to result in savings of chemicals, water, reduce the effluent quantity and related problems of treatment and disposal. Machineries with new designs and new process techniques are developed for minimising the requirement of water. 

In early days of Phase I, the predominant feedstock for ammonia synthesis was coke. Synthesis gas was either produced at atmospheric pressure in water-gas shift units or prepared by purification of coke oven gas. In these early plants, the process effluents from the ammonia converter were cooled without recovery of heat. Due to the lack of technology regarding the attainable size of the converter pressure shell, the physical dimensions of the converter were limiting factors for the achievable production capacity. Therefore, a particular emphasis was placed on maximization of the production capacity for a given volume [139]. During World War II, several plants were built in the United States, based on natural gas feedstock. Since then, natural... 

The effectiveness of a waste destruction process can be tracked by following the disappearance of a chemical compound that is especially resistant to the process conditions. The working assumption is that, if the tracking compound is completely destroyed, other less stable chemicals will also be absent in the process effluents. The fate of certain chemical species of particular regulatory or public concern, such as persistent organic pollutants (POPs) or toxic heavy metals, may also be used to track the performance of treatment technologies. 

In spite of the copious theories for the decanter centrifuge, it is not possible to predict performance with any particular process material simply from knowledge of pertinent physical parameter values, that is, without prior knowledge of the process material s behaviour on a decanter. Test work Is essential on any new, or unknown, sludge and on any sludge, such as effluents, that can vary widely in composition and/or quality. 

The resultant slag, a complex mixture of titanates, may contain 70—85% Ti02- The slag route is particularly useful when ilmenite is closely associated with haematite, from which it cannot economically be separated mechanically. Because the iron content of the slag is low, its use reduces the quantity of iron sulfate in the Hquid effluent of sulfate process plants. Slag used as a feedstock for TiCl production must be low in magnesium and calcium. A variety of other ilmenite beneficiation or synthetic mtile processes have been pursued, primarily to provide alternative chloride process feedstocks. Low grade ilmenite... 

The Catalytic Wet Air Oxidation (CWAO) process is capable of converting all organic contaminants ultimately to carbon dioxide and water, and can also remove oxidizable inorganic components such as cyanides and ammonia. The process uses air as the oxidant, which is mixed with the effluent and passed over a catalyst at elevated temperatures and pressures. If complete COD removal is not required, the air rate, temperature and pressure can be reduced, therefore reducing the operating cost. CWAO is particularly cost-effective for effluents that are highly concentrated... 

A final option for dealing with the bromide effluent problem is to recover the bromine for re-use giving a more environmentally acceptable effluent. The alternative approaches will be discussed in detail later, but H2O2 offers particular attractions in terms of giving a cleaner process. 

Whilst this process is attractive in that it removes an effluent problem and fully utilises the bromine used, it must be recognised that for some reactions, particularly where there is a degree of water sensitivity, the approach will not be practicable. 

As noted earlier, diverse forms of organomercury are released into the environment as a consequence of human activity. Methyl mercury presents a particular case. As a product of the chemical industry, it may be released directly into the environment, or it may be synthesized in the environment from inorganic mercury which, in turn, is released into the environment as a consequence of both natural processes (e.g., weathering of minerals) and human activity (mining, factory effluents, etc.). 

Process operation and the storage and handling of effluents and chemicals involve potential chemical and biological hazards (Chapter 5). Safeguards of the type outlined in Chapters 12 and 13 are essential, particularly since the activities are often on a site s periphery and have low manning levels. 

Electrochemical processes are particularly well suited for the manufacture of fine chemicals in view of their high sjjecificity (almost comparable to that offered by enzymes), the smaller number of steps required, adoption of milder conditions, lack of scale-up problems, avoidance of effluents, etc. The ease with which oxidation and/or reduction can be carried out with the practically mass-free clean electrons makes electrochemical processes well suited for such jobs, including paired synthesis in effect, we use electricity as a reagent . Consider a standard chemical oxidant like manganic or chromic sulphate. Here, a stoichiometric amount of the reduced salt will be formed the disposal of which can be a serious problem. If we adopt an electrochemical process, then the reduced salt is converted into the desired oxidized salt. 

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