Sludge processes, wastewater

Residual sulfur dioxide or hydrogen sulfide Air pollution control (APC) dust and/or waste treatment plant sludge Process wastewater Kish... 

Process water streams from vinyl chloride manufacture are typically steam-stripped to remove volatile organics, neutralized, and then treated in an activated sludge system to remove any nonvolatile organics. If fluidized-bed oxychlorination is used, the process wastewater may also contain suspended catalyst fines and dissolved metals. The former can easily be removed by sedimentation, and the latter by precipitation. Depending on the specific catalyst formulation and outfall limitations, tertiary treatment may be needed to reduce dissolved metals to acceptable levels. 

SoHd by-products include sludge from wastewater treatment, spent catalyst, and coke from the EDC pyrolysis process. These need to be disposed of in an environmentally sound manner, eg, by sludge digestion, incineration, landfill, etc. 

Process Va.ria.tlons, There are many variations of the activated sludge process which have been developed in response to different wastewater... 

Activated Sludge. There are several generic activated sludge processes presendy available. Complete Mix (CMAS) is appHcable to refractory-type wastewaters in which filamentous bulking is not a problem. This process has the advantage of dampening ductuations of induent wastewater quaUty. 

Fig. 2. Typical flow sheet for a domestic wastewater treatment plant utilizing the activated-sludge process.

If a waste is a mixture of water and organic liquid, you must report it as wastewater unless the organic content exceeds 50 percent. Slurries and sludges containing water must be reported as solid waste if they contain appreciable amounts of dissolved solids, or solids that may settle, such that the viscosity or density of the waste is considerably different from that of process wastewater. 

Aerobic Treatment. The activated sludge process depends on aerobic biological action. In this case the microorganisms, in searching for food, break down the complex organic substances into simple stable substances. This process results in the removal of soluble and suspended organic matter from wastewater. 

The activated sludge process for domestic wastewater treatment was introduced to the world in 1914.1 Since then, many studies have been conducted to improve the oxygen transfer efficiency. Among the aeration devices introduced have been a porous diffuser, a filter type diffuser, a mechanical aeration device, an orifice type diffuser and a fine-pore air diffuser. The aeration market is in a substantial state of flux in the USA today. Emphasis on high efficiency has led many intensive research programmes to aim at the evaluation of the design, operation and control processes to improve overall system performance. 

The activated sludge process for wastewater treatment uses recycle of live cells. The goal is to oxidize organics without generating too much sludge (i.e., biomass). 

Semifinished steel shapes Process wastewater Scale Sludge... 

Cleaned steel products (e.g., sheets, plates, bars, pipe) Process wastewater containing mill scale, oils, other pollutants, and low levels of metals Wastewater sludge Air pollution control (APC) dust Spent pickle liquor (K062)... 

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 process is similar to the activated sludge process however, it requires a large surface area to cause more temperature effects than that experience in the activated sludge process. The aeration process in this system supplies oxygen to the influent wastewater and the turbulent generated keeps the contents of the basin in suspension. The suspended solids are then removed in a settling tank where the wastewater may further be treated before discharge.23... 

The activated sludge process for meat processing wastewater treatment was reported by Annachhatre and Bhamidimarri.37 When a model reactor was operated at an HRT of 5-15 h, a COD removal of more than 85% was achieved. The COD loading for the above performance was 3.2kg COD/(m3d). An SRT of 13 d resulted in almost complete nitrification. El-Gohary et al.30 reported that the activated sludge process reduced the BOD and COD of a potato-chips factory wastewater by 86% and 84%, respectively. The organic loading rate and HRT were reported as 8.9 kg BOD/ (m3d) and 6h, respectively. 

N20 production in order of effect size of treatment was wastewater sludge (H-SLUDGE) > vermicomposting > wastewater sludge (L-SLUDGE) > urea > unfertilized soil. Nitrifier nitrification and nitrifier denitrification were presumably the processes that contributed the most to the production of NzO under aerobic conditions. 

For waste treatment rather than fermentation for product formation, again few examples of process economics exist in the literature. Those that do, favor fluidization. Badot et al. (1994) described an industrial prototype fluidized bed reactor that competed favorably on an economical basis with activated sludge processes for treating carbon pollution and was estimated to be economically comparable to fixed bed processes for denitrification. Schneeberg (1994) described the successful and economically-sound implementation of fluidization as an upgrade to an existing wastewater treatment plant. The restricted space available for extension of the wastewater plant made fluidization particularly advantageous in this case. 

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