Wastewater clarification

Chargepac . [Drew Ind. Div.] Coagulants for water and wastewater clarification. 

WorieeAdd 902 WorieeAdd 904 deaerating agem, wastewater clarification... 

RO, primarily used ia the dairy iadustry, is expanding iato other areas of food processiag. RO can be used for a variety of operations, ranging from wastewater treatment and material recovery to clarification and concentration. Material recovery is advantageous for two reasons. By recovering valuable products, eg, proteias, from waste streams, profits can be iacreased while costs for waste disposal decreased. An excellent review of the different apphcations ofRO ia food processiag is available (9). 

For wet ESPs, consideration must be given to handling wastewaters. For simple systems with innocuous dusts, water with particles collected by the ESP may be discharged from the ESP system to a solids-removing clarifier (either dedicated to the ESP or part of the plant wastewater treatment system) and then to final disposal. More complicated systems may require skimming and sludge removal, clarification in dedicated equipment, pH adjustment, and/or treatment to remove dissolved solids. Spray water from an ESP preconditioner may be treated separately from the water used to wash the ESP collecting pipes so that the cleaner of the two treated water streams may be returned to the ESP. Recirculation of treated water to the ESP may approach 100 percent (AWMA, 1992). 

Lime is somewhat different from the hydrolyzing coagulants. When added to wastewater it increases pH and reacts with the carbonate alkalinity to precipitate calcium carbonate. If sufficient lime is added to reach a high pH, approximately 10.5, magnesium hydroxide is also precipitated. This latter precipitation enhances clarification due to the flocculant nature of the Mg(OH)2. Excess calcium ions at high pH levels may be precipitated by the addition of soda ash. The preceding reactions are shown as follows ... 

Diatomaceous earths may resemble the forms of the charcoals. The earths are primarily filter aids, precoats or adsorbents, the hmction of the filter medium being secondary. Fuller s earth and clays are used for decoloring applications diatomaceous earths are used for clarification. The adsorbtivity of diatomaceous earth works in the same fashion as activated carbon, but isotherms (affinity) for many chemical species like the hydrocarbons is weaker. For this reason, activated charcoal or carbon is much preferred in wastewater treatment applications expecially when taste and odor issues are priorities. 

Clarification A process in which suspended material is removed from a wastewater. This may be accomplished by sedimentation, with or without chemicals, or filtration. 

Alumina clarification Alumina slurry, starch, Wastewater ... 

Wastewaters generated from primary aluminum processing are produced during clarification and precipitation, although much of this water is fed back into the process to be reused. 

Full Scale Treatment of Aluminum Forming Wastewater by Chemical Precipitation and Clarification... 

The precipitated metal hydroxide can then be removed from the wastewater by clarification or other solid-water separation techniques.52... 

The modified reduction-flotation wastewater treatment system (Figure 6.5) will be very attractive if all or most of an existing wastewater treatment facilities are to be reused. The high-rate DAF clarifier is a very low-cost clarification unit. 

Removal of Total Suspended Solids and Oil and Grease from Coil Coating Wastewater by Emulsion Breaking and Clarification Process... 

Granular bed filters are used in ten coil coating plants to remove residual solids from the clarifier effluent, and are considered to be tertiary or advanced wastewater treatment. Chemicals may be added upstream to enhance the solids removal. Pressure filtration is also used in this industry to reduce the solids concentration in clarifier effluent and to remove excess water from the clarifier sludge. Figure 7.4 shows a granular bed filter and Table 7.13 presents the heavy metal removal data of a lime clarification and filtration system. 

Removal of Heavy Metals from Coil Coating Wastewater by Lime Precipitation, Clarification, and Filtration... 

This plant produces 130 m2/h of enameled steel and operates 3500 h/yr. It uses 0.0036 m3 water/m2 of product to coat the steel. Average process water flow is 0.144 m3/h for coating operations and 0.734 m3/h for metal preparation. The primary treatment in-place for process wastewater is clarification and settling. Other water treatment practices employed are pH adjustment with lime or acid, sludge applied to landfill, polyelectrolyte coagulation, and inorganic coagulation. 

This facility produces 210 m2/h of enameled aluminum and uses 0.015 m3 water/m2 of product for coating operations. The average process flow rate is 1.33 m3/h for metal preparation operations and 0.716 m3/h for coating operations. The primary in-place treatment for process wastewater is chemical coagulation and clarification (i.e., settling). 

This facility produces 360 m2/h of porcelain enameled aluminum for 4000 h/yr, and uses 0.038 m3 of process water/m2 of product coated. The mixed wastewater stream is treated by equalization (settling), pH adjustment (lime or acid), polyelectrolyte coagulation, clarification, and contractor removal of the resulting sludge prior to discharge to a surface stream. Process water flow for this production consists of 8.12 m3/h and 4.37 m3/h for surface preparation and coating operations, respectively.3 5... 

This facility produces 9.1 m2/yr of porcelain enameled cast iron. The primary in-place treatment for process wastewater is chemical coagulation, clarification (settling), and skimming. 

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