Filtration media

Granular media filtration is used for treating aqueous waste streams. The filter media consists of a bed of granular particles (typically sand or sand with anthracite or coal). The anthracite has adsorptive characteristics and hence can be beneficial in removing some biological and chemical contaminants in the wastewater. This material may also be substituted for activated charcoal. 

E. Very low solids concentration (i.e. clarification duty), or containing solids which blind normal filter media Filtrate usually required. 

Mixed-media filtration Up to 95% of free oils. Efficiency in removing emulsified oils unknown. 

A third plant uses a chemical precipitation step for removing arsenic and zinc from contaminated surface water runoff. Ferric sulfate and hme are alternately added while the wastewater is vacuum-filtered and sludge is contract-hauled. The entire treatment system consists of dual-media filtration, carbon adsorption, ion exchange, chemical precipitation, and vacuum hltration. Sampling results across the entire treatment system indicated that arsenic was reduced from 6.9 to 0.2 mg/L and zinc from 0.34 to 0.11 mg/L. 

Mixed-Media Filtration of Oily Waste Waters... 

There are many granular filter systems available. The purpose of this paper is to discuss mixed-media filtration — how it was developed, where it has been used, and its application to the petroleum industry. 

The development of mixed-media filtration and its application to oily wastes, including oilfield-produced water, refinery waste water, and other waters containing oil, is reviewed. Several case histories are presented and data show that simple filtration through mixed-media filters can remove essentially all visible oil. 

To provide this finished water quality, a system incorporating flocculation, settling, and mixed-media filtration is used. Fig. 6 schematically illustrates the flow of the system used. After flocculation, the coagulated water is processed through a shallow-depth sedimentation basin using tube settlers. Tube settlers provide efficient sedimentation in greatly reduced detention times. The tube settlers are essentially a honeycomb of 1-in. trays operating in parallel. The... 

A mixed-media filtration study on an asphalt plant effluent was also conducted. In this case, the oily waste contains a heavy fraction of asphalts. Typical influent quality to the filter was 30 to 40 ppm oil and 30 to 50... 

Media filtration capsules, 0.2-pm pore size (Gelman Sciences) (see Note 8). 

Traditional pretreatments make an extensive use of chemicals (NaCIO as disinfection, FeCl3 as flocculants, H2S04 as antiscaling agent) and mechanical filtration units (sand filtration, media filtration, cartridge filtration). 

An integrated water-treatment system designed to use different water sources and different treatment processes, including membrane processes, has been realized in Temeuzen (The Netherlands) [15]. Raw-water sources and treatments include seawater and integrated membrane system to produce demineralized water fresh water, and ion exchange to produce demineralized water effluent industrial wastewater-treatment plant (WWTP) and media filtration to produce cooling tower supply water. 

Media filtration this step includes multimedia filtration or high-efficiency filtration, and reduces the concentrations of suspended solids, turbidity, and SDI. 

This type of filtration is typically only used on well water sources. In some cases, media filtration is not required prior to greensand filtration. 

There have been some efforts in slurry recycling to reduce CoO of CMP consumables. In a recent study [37], the effluent samples were characterized for pH, trace-metal levels, viscosity, specific gravity, mean aggregate particle size, and LPC (>1.0 rm) before and after depth (melt-blown polymeric media) filtration. The study showed that the use of a recycled fumed silica slurry (recycled five times) decreased the CMP removal rate and the coefficient of friction (COF) by 40%. A perfect relationship was observed between the removal rate and COF. It was concluded that the increase in mean aggregate particle size, which lowers the contact area between the abrasive particles and the wafer, had some impact on the removal rate data. In general, there is a stronger emphasis on slurry additives and chemical action in current CMP processing with much lower maximum defectivity performance specifications [2]. 

Beigman L., The world market for hot gas media filtration Current status and state of the art, in Gas Cleaning at High Temperatures, Clift R. and Seville J.RK., eds.. Chapman Hall, London (1993), p. 294. 

Field evaluation of a hybrid membrane system consisting of an UF membrane pretreatment unit and an RO seawater unit was conducted by Glueckstem et al. [56]. For comparison a second pilot system consisting of conventional pretreatment and an RO unit was operated in parallel. The conventional pretreatment unit included in-line flocculation followed by media filtration. The smdy showed that UF provided a very reliable pretreatment for the RO system independent of the raw water quality flucmations. However, the cost of membrane pretreatment was higher than conventional pretreatment. This suggested that membrane pretreatment for RO desalting systems is only economic for sites that require extensive conventional pretreatment or where wide flucmations in the raw water quality are expected. 

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