Wastewater polishing

Quench waste recirculation requires installation of a cooling tower to lower the temperature of the quench wastewater stream. The multimedia filter system for the final polishing of effluent includes a backwash mechanism, pumps, control media, and the filter structure. 

Granular bed filters are used in porcelain enameling wastewater treatment to remove residual solids from clarifier effluent (sedimentation effluent or flotation effluent). Filtration polishes the effluent and reduces suspended solids and insoluble precipitated metals to very low levels. Fine sand and coal are media commonly utilized in granular bed filtration. The filter is backwashed after becoming loaded with solids and the backwash is returned to the treatment plant influent for removal of solids in the clarification step.10-12... 

Hajdow MWTP is a typical Polish municipal wastewater treatment plant and consists of primary (mechanical) treatment part and secondary (biological) treatment part. Total treatment procedure lasts about 22 hours. The primary sludge and excess sludge are water reduced separately and go together to the digester. 

In some cases (particularly reactive dyes) dyes can pass the aerobic, anaerobic degradation step and colored water is observed at the end of the treatment. In such cases a special treatment of the colored wastewater (reduction, adsorption, precipitation) has to be introduced [105,134-137]. In the presence of low concentrations of organic compounds, ozonation can be used as a final polishing step. 

Some fixed filtration systems are relatively inexpensive. For example, constructed wetlands and sand filters are generally the most successful methods of polishing the treated wastewater effluent from lagoons. These systems have also been used with more traditional, engineered primary treatment technologies such as septic tanks and primary clarifiers. In such constructed wetlands, the system utilizes the roots of plants to provide substrate for the growth of attached bacteria, which utilize the nutrients present in the effluents and for the transfer of oxygen. 

The Unipnre Environmental, Unipnre process technology is a unique iron co-precipitation method for removal of heavy metals from waste streams or groundwater. It can act as a primary metal-removal system or as a polishing step to an existing treatment system. The reactor mod-nle replaces the nentrahzation tank in a conventional wastewater treatment system. The process prodnces solids that are extremely insolnble in water and mild acid solutions. 

Special applications The environmental control and life support system on a spacecraft maintains a safe and comfortable environment, in which the crew can live and work, by supplying oxygen and water and by removing carbon dioxide, water vapor, and trace contaminants from cabin air. It is apparent that the processes aimed at the recycling of air and water are vital for supporting life in the cabin. These recycling processes include separation and reduction of carbon dioxide, removal of trace gas-phase contaminants, recovery and purification of humidity condensate, purification and polishing of wastewater streams, and are performed totally or in part by adsorption equipment (Dabrowski, 2001). ... 

Alternate technologies have recently become available to deal with certain types of waste materials. Ion-exchange and bio-recovery offer the attractive potential of recovering metals from waste water for re-use in the primary process, but these techniques are limited to low concentration, aqueous solutions of metal ions, and thus are more suited for "polishing" a wastewater stream before discharging it to city wastewater treatment facilities. In many cases, capital costs for these techniques are prohibitive relative to the value of the metal recovered. 

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