Effluent treatment passivation

The wash water and the spent acid from all the pre-treatment tanks is also transferred to the effluent treatment plant for further treatment. Spent passivation liquor from the passivation tank is a strong waste and it may be provided with a separate pipeline to the effluent treatment plant, as shown in Figure A13.12. 

Effluent is associated not just with many process industries, as has been illustrated above in the case of the textile finishing industry, but also with most aspects of our urban existence. The need to treat effluent arises for several reasons. Some effluents can be transformed into useful products, such as feedstock for animals or even pharmaceutical products the ability to concentrate effluent, particularly in an energy-efficient manner, can reduce disposal costs and the ability to recycle effluents, once separated from less desirable components, can also be economically beneficial. The link between effluent treatment and PI is strong and growing, as the above influences become the subject of legislation or economic necessity. The range of techniques that can be used to aid clean-up covers both active and passive intensification methods. Included below are several examples including the use of ultrasound already dealt with in a number of process uses in this chapter. 

MANAGEMENT OF PASSIVE BIOLOGICAL WATER TREATMENT SYSTEMS FOR MINE EFFLUENTS... 

Dechlorination is the process of converting highly reactive chlorine from these waters into less reactive chloride ions prior to disposal into receiving streams. Various chemical and nonchemical techniques are currently used for disposal of chlorinated waters by water and wastewater agencies. For example, wastewater treatment plants use sulfur dioxide gas or sodium metabisulfate to dechlorinate treated effluent prior to release into receiving streams. Many water utilities often use passive, non-chemical methods such as discharge to sanitary sewers for disposal of chlorinated waters. Impurities such as organics, iron, and sulfide in the sanitary sewer exert a chlorine demand and neutralize chlorine in the released water. 

The first js the pyrolysis of acetone in a tubular reactor. As for the cracking of acetic arid, it is preferable to use chromium steel (25 per cent) tubes. The use of conventional alloys may be feasible after passivation of the inner walls by a mixture of H2 and CO. or by prior treatment with steam, or by the injection of small amounts of sulfur compounds (H,S, CS etc.). The effluents leaving the furnace are quenched in two stages ... 

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