6 Chemical Unit Processes 6-1 Role of Chemical Unit Processes in Wastewater Treatment The principal chemical unit processes used for wastewater treatment include(1)chemical coagulation, (2) chemical precipitation,(3)chemical disinfection,(4)chemical oxidation,(5)advanced oxidation processes,(6)ion exchange, and(7)chemical neutralization, scale control, and stabilization application of Chemical Unit Processes Applications of chemical unit processes for the management and treatment of wastewater are reported in Table 6-1 Tab. 6-1 Applications of chemical unit process in wastewater treatment Application Advanced oxidation processes Removal of refractory organic compounds Chemical coagulation The chemical destabilization of p an wastewater to bring about their aggregation during perikinetic and orthokinetic Flocculation Chemical disinfection Disinfection with chlorine, chlorine compounds, bromine, and。zone Control of slime growths in sewers Control of odors Chemical neutralization Control of pH Chemical oxidation Removal of BOD, grease, etc. Removal of ammonia(NH:) estruction of microorganisms pump stations, and treatment plants Removal of resistant organic compounds Chemical precipitation Enhancement removal of total suspended solids and BOD i rimary sedimentation facilities emoval of phosphorus Removal of heavy metals Physical-chemical treatment Corrosion control in sewers due to has Chemical scale control Chemical stabilization Stabilization of treated effluents lon exchang emoval of ammonia (NH4), heavy metals, tot solved solids emoval of organic compound Chemical processes, in conjunction with various physical operations, have been developed for the complete secondary treatment of untreated(raw)wastewater, including the removal of either nitrogen phosphorus or both. Chemical Fig. 6-1 have also beer Typical lime clarification developed remove facilities following phosphorus by chemical secondary treatment used precipitation, and are designed pretreatment step for advanced treatment of to be used in conjunction with wastewater using reverse biological treatment Other osmosis. Lime storage is chemical processes have been in the silo shown behind developed for the removal of building that is used eavy metals and for ific to house the lime slaking acilities and the reverse organic compounds and for the mosis units, used for advanced treatment odvanced treatment wastewater. Currently the most Granular medium-depth ant filters are shown to ight of the lime clarifier wastewater treatment are for(1) the disinfection of wastewater. 2)the precipitation of phosphorus and (3) the coagulation of particulate matter found in wastewater at 6-16-1 6 Chemical Unit Processes 6-1 Role Of Chemical Unit Processes In Wastewater Treatment The principal chemical unit processes used for wastewater treatment include (1) chemical coagulation, (2) chemical precipitation, (3) chemical disinfection, (4) chemical oxidation, (5) advanced oxidation processes, (6) ion exchange, and (7) chemical neutralization, scale control, and stabilization. Application of Chemical Unit Processes Applications of chemical unit processes for the management and treatment of wastewater are reported in Table 6-1. Tab. 6-1 Applications of chemical unit process in wastewater treatment Chemical processes, in conjunction with various physical operations, have been developed for the complete secondary treatment of untreated (raw) wastewater, including the removal of either nitrogen or phosphorus or both. Chemical processes have also been developed to remove phosphorus by chemical precipitation, and are designed to be used in conjunction with biological treatment. Other chemical processes have been developed for the removal of heavy metals and for specific organic compounds and for the advanced treatment of wastewater. Currently the most important applications of chemical unit processes in wastewater treatment are for (1) the disinfection of wastewater, (2) the precipitation of phosphorus, and (3) the coagulation of particulate matter found in wastewater at Fig. 6-1