Sewage sludges

Washing and dewatering by air displacement of cakes are possible. AppHcations are in the treatment of minerals, in the sugar industry, and in the treatment of municipal sewage sludge and fillers like talc, clay, whiting, etc. 

The ECLP tube press was originally developed for the filtration of china clay but has been used with many other slurries such as those in mining, Ti02, cement, sewage sludge, etc. The typical cycle time is about four minutes or more. 

The vertical recessed plate automatic press, shown schematically in Figure 15 and described previously, is another example of a horizontal belt pressure filter. Cycle times ate short, typically between 10 and 30 minutes, and the operation is fully automated. The maximum cake thickness is about 35 mm washing and dewatering (by air displacement) of cakes is possible. Apphcations include treatment of mineral slurries, sugar, sewage sludge, and fillers like talc, clay, and whiting. 

Originally designed for the continuous filtration of conditioned sewage sludges, as were most of the filter belt presses available, the Manor Tower press is increa singly used for the treatment of paper mill sludge, coal, or flocculated clay slurries. 

The chemical characteristics of biomass vary over a broad range because of the many different types of species. Table 8 compares the typical analyses and energy contents of land- and water-based biomass, ie, wood, grass, kelp, and water hyacinth, and waste biomass, ie, manure, urban refuse, and primary sewage sludge, with those of cellulose, peat, and bituminous coal. Pure cellulose, a representative primary photosynthetic product, has a carbon content of... 

Analysis Pure ceUulos e Pine wood Kentuck y bluegrass Giant brown kelp Feedlo t manur e Urban refuse Primary sewage sludge Reed sedge peat Illinois bituminous coal... 

Ana.eroblc Digestion. Methane can be produced from water slurries of biomass by anaerobic digestion in the presence of mixed populations of anaerobes. This process has been used for many years to stabilize municipal sewage sludges for purposes of disposal. Presuming the biomass is all cellulose, the chemistry can be represented in simplified form as follows ... 

F/uidi ed-BedIncinerator. Fluidized-bed incinerators are employed in the paper and petroleum (qv) industries, in the processing of nuclear wastes, and the disposal of sewage sludge. These are quite versatile and can be used for disposal of soflds, Hquids, and gaseous combustible wastes. 

The methacrylates ate slightly to essentially nontoxic to fish and other aquatic species. Hydrolysis data suggest rapid breakdown at alkaline conditions, and studies show that MMA is ultimately biodegradable ia sewage sludge samples. Based on this information, the methacrylates ate not considered to be a significant environmental hazard. 

PermeOx is also used to improve the bioremediation of soils contaminated with creosote or kerosene (see Bioremediation (Supplement)), to deodori2e sewage sludges and wastewater (see Odormodification), and to dechloriaate wastewater and effluents. A special formulation of calcium peroxide, made by FMC and sold ia the United States under the trademark Trap2ene, is used for removing metal ions from acidic waste streams such as coal ash leachate and acid mine drainage (see Wastes, industrial). 

ASTM D5271-93 aerobic activated sewage sludge O2 and CO2... 

Linear alkylbenzenesulfonate showed no deleterious effect on agricultural crops exposed to this material (54,55). Kinetics of biodegradation have been studied in both wastewater treatment systems and natural degradation systems (48,57,58). Studies have concluded that linear alkylbenzenesulfonate does not pose a risk to the environment (50). Linear alkylbenzenesulfonate has a half-life of approximately one day in sewage sludge and natural water sources and a half-life of one to three weeks in soils. Aquatic environmental safety assessment has also shown that the material does not pose a hazard to the aquatic environment (56). 

The radioactive isotope Cs is important commercially in process control instmments and for sewage sludge sterilisation. The isotope has along half-life — 30 yi )i however, it must be weU-shielded because of the high biological hasard. 

Screw presses (Fig. 2) do not produce a clear liquid product. Frequendy, the product is further filtered in a filter press to give a clear Hquid product. Press aids are added to feed materials containing fine particles or particles that can deform and plug the slots in the edge of a screw press. Typical press aids include sawdust, rice hulls, perlite, and diatomaceous earth (see Diatomite). A vertical screw press is a continuous press that has been used for dewatering sewage sludge (2). 

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