Adsorption system, carbon wastewater

The process of adsorption on carbon is applicable to wastewaters and polluted air. Treated waters may be suitable for reuse in industrial processes and can be discharged safely to the sewer system if removal efficiencies are high enough. Hazardous constituents of no commercial value that are removed may be disposed in burial sites after they have been stabilized. The high capacity of activated carbon for many compounds is attributable to the large surface area of the carbon (500-1500 m2 g-1). 

The Jet Propulsion Laboratory (JPL) Process (20) has also been the subject of study. This process is a two-stage countercurrent adsorption system using PAC. Fresh activated carbon is mixed with wastewater in the secondary mixing basin and settled, and then the entire mixture of settled sewage solids and activated carbon is transferred to the primary mixing basin. Settled solids and carbon are removed from the primary settling basin, dewatered, and transferred to a pyrolysis reactor. The reactor produces activated carbon, which is then recycled to the secondary mixing basin. 

In wastewater treatment, carbon adsorption systems often use granular activated carbon. The design of the activated carbon system consists essentially in determining ... 

Remediation. Many companies specialize in hazardous-waste remediation by providing a variety of disposal services and equipment, not limited to catalytic oxidizers and carbon adsorption systems. Remediation includes reduction and cleanup of hazardous wastewater by using oil-water separators to separate oil and solids from wastewater effluents of petroleum-based industries. Other hazardous-vwiste remediation services include demolition and removal of hazardous materials such as asbestos, removal of leaky fuel tanks, cleanup of contaminated sods, and the construction of slurry walls to aid in the remediation of groundwater that is polluted with hazardous waste. Bioremediation is also a growing field that involves disposal of medical and laboratory wastes often by using microorganisms to break down the hazardous materials. 

In addition to anionic species, some metal cations can also be removed via adsorption processes with LDH materials. Recently, Lazaridis reported an interesting removal of two anions (P04 , SCN ) and three cations (Cd , Pb ", Ni " ) from aqueous solutions in single batch systems using uncalcined and calcined (773 K) Mg/Al LDH carbonate materials [148]. It was found that the calcined material showed higher sorption capacities than the uncalcined material for all the ions. Since the sorption capacities are relatively high, the author suggested that LDHs could be considered as a potential materials for sorption of both anions and cations in wastewater treatment systems. Seida et al. have also reported the rapid removal of dilute Pb from dilute aqueous solutions by a column packed with a pyroaurite-like Mg/Fe-COs LDH compound over a wide range of space velocity (Sv = 150-800 min" ) [149]. 

Activated carbon adsorption is a well-established process for adsorption of organics in wastewater, water, and air streams. Granular activated carbon (GAG) packed in a filter bed or of powdered activated carbon (PAG) added to clarifiers or aeration basins is used for wastewater treatment. In the pesticide industry, GAG is much more widely used than PAG. Figure 10 shows the process flow diagram of a GAG system with two columns in series, which is common in the pesticide industry [11]. 

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. 

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). ... 

That carbon adsorption is deemed a suitable technology for a variety of water and wastewater treatment applications is evidenced by the substantial shift of the technology from pilot to full scale implementation over the past decade. However, and particularly in the case of wastewaters, it is difficult to generalize or extrapolate system design from one situation to another, even within a given... 

On the basis of the total amount of organic matter removed during the process, it was found that the activated carbon had adsorbed well above its adsorption capacity (Table 2). Tbe total amount of the adsorbed organic matter was determined as the difference of the integrals for the surface under the curves showing dependence of the organic matter concentration in the influent, respectively, and the volume of the wastewater passed through the system. 

If powdered activated carbons (or other adsorbents) are added to water or wastewater for removing soluble pollutants, the spent carbons are then flocculated and floated by a dissolved air flotation cell (or by an electroflotation cell), in which no foam is produced, the process system is termed nonfoaming adsorption flotation (83). 

L. K. Wang, Feasibility Study of Treating Field Military Wastewater by a Process System Including Powdered Carbon Adsorption, Polymer Coagulation, and Diatomite Filtration, US Defense Technical Information Center, Alexandria, VA, ADA077198, June, 1973. 

There are many methods for the desulfurization of nature gas, which can be classified into dry desulfurization, wet desulfurization, and catalytic adsorption. In the dry desulfurization, some solid sorbents, such as iron oxide, zinc oxide, activated carbon (AC), zeolites, and molecular sieves, are used. In wet desulfurization method, liquid-phase chemical/physical solvent absorption systems are usually used for scrubbing H2S amine-based processes are subject to equipment corrosion, foaming, amine-solution degradation, and evaporation, and require extensive wastewater treatment. As a result, this sulfur removal technology is complex and capital intensive,44 although the processes are still employed widely in the industry. The desulfurization of coal gasification gas will be reviewed in detail in Section 5.5. In the catalytic-adsorption method, the sulfur compounds are transformed into H2S by catalytic HDS or into elemental sulfur or SOx by selective catalytic oxidation (SCO), and then, the reformed H2S and SOx are removed by the subsequent adsorption. 

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