Wastewater treatment, inorganic chemicals production

Miscellaneous. Hydrochloric acid is used for the recovery of semiprecious metals from used catalysts, as a catalyst in synthesis, for catalyst regeneration (see Catalysts, regeneration), and for pH control (see Hydrogen-ION activity), regeneration of ion-exchange (qv) resins used in wastewater treatment, electric utiUties, and for neutralization of alkaline products or waste materials. In addition, hydrochloric acid is also utilized in many production processes for organic and inorganic chemicals. 

Tang H.X., Tian B.Z., Luan Z.K., Zhang Y. (1994), Inorganic polymer flocculant polyfertic chloride, its properties, efficiency and production. Chemical Water and Wastewater Treatment III, 57-69. 

Over half the quantity of wastes is accounted for by three large groups 27 % wastes not associated with chemical production (building rubble, excavated soil, wastes from energy production facilities) 17% from wastewater and water treatment and 16% inorganic sludges. 

Very often the use of process water and/or the treatment of wastewater requires the use of inorganic or organic additives. Sometimes these additives have to be considered later on as pollutants, sometimes as compounds of which the concentration in the process water should not be too high. It is therefor not allowed that the concentration of these additives exceeds a maximal admissible value. This means that in case of a continuous closed loop system, the physical/chemical treatment step has to remove an amount of these compounds corresponding to the amount of these compounds added elsewhere in the closed loop water system, minus the amount consumed in the production process. Often the consequence is that only relatively low removal efficiency in the treatment step is necessary. 

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