Biotreatment Plants

It has become increasingly unacceptable in recent years to allow even small amounts of organic waste from chemical production processes to enter public sewerage and water systems. An increasingly common solution has been the installation of biotreatment plants. Frequently all rainwater falling onto the production site is also collected and diverted, via storm water drains, into the biotreatment plant as well as aqueous effluent 

The preferred aerobic degradation pathway for aromatic compounds is via 1,2-dihydroxybenzene (catechol), which involves the enz3rmes mono- 

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Toxicity. Low toxicity from solvent-vapor inhalation or skin contac t is preferred because of potential exposure during repair of equipment or while connections are being broken after a solvent transfer. Also, low toxicity to fish and bioorganisms is preferred when extraction is used as a pretreatment for wastewater before it enters a biotreatment plant and with final effluent discharge to a stream or lake. Often solvent toxicity is low if water solubility is high. 

The biotreatment plant is designed to operate 24 hours per day, seven days per week, and to handle hydrolysate from 7,000 pounds of agent per day. The design throughput is less than the overall plant design capacity of 10,000 lbs of agent per day, which means the biotreatment plant can handle... 

Air stripper off-gas from the VOC system in the process auxiliary building is passed through carbon filters. The gases from the biotreatment plant also pass through deep-bed carbon filters. The amounts of off-gas handled by these four systems in standard cubic feet per minute (scfm) are shown in Table A-3. 

Discuss the role of biotreatment plants in a modem chemical production facility. 

A bleed from the scmbbing system is sent to a sour slurry stripper. The water is then clarified and can be recycled to minimize the volume of effluent to be biotreated and discharged or evaporated. The acid gas from the acid gas removal system and from the sour slurry stripper is fed to a Claus plant, where salable elemental sulfur (qv) is produced. For maximum sulfur recovery and minimal sulfur emissions, the Shell Claus off-gas treating process (SCOT) is used. 

The first step in the analysis is to identify the target for debottlenecking the biotreatment facility. An overall water balance for the plant (Fig. 4.4) can be written as follows ... 

Influent to biotreatment is reduced to 40% of current level. Therefore, the plant production can be expanded 2.5 times the current capacity before the biotreatment facility is debottlenecked again. 

The scope of the previously addressed CE case study is now altered to allow for stream segregation, mixing, and recycle within the ethyl chloride plant. There are five sinks the reactor (u = 1), the first scrubber (u = 2), the second scrubber (u = 3), the mixing tank (u = 4) and the biotreatment facility for effluent treatment (m = 5). There are six sources of CE-laden aqueous streams (in = 1-6). There is the potential for segregating two liquid sources (lu = 2, 4). The following process constraints should be considered ... 

The plant disposes of two waste streams gaseous and aqueous. The gaseous emission results from the ammonia and the artunonium nitrate plants. It is fed to an incinerator prior to atmospheric disposal. In the incinerator, ammonia is converted into NOj,. Ehie to more stringent NO regulations, the conqmsition of ammonia in the feed to the incinerator has to be reduced from 0.57 wt% to 0.07 wt%. The lean streams presented in Table 9.5 may be employed to remove ammonia. The main aqueous waste of the process results from the nitric acid plant. Due to its acidic content of nitric acid, it is neutralized with an aqueous ammonia solution before biotreatment. 

During a field test of SABRE technology conducted at the DOD s Iowa Army Ammunition Plant, the U.S. Army Environmental Center evaluated the performance and cost of biotreatment as an alternative to incineration of munitions. Cost projections for this demonstration estimate a unit cost of approximately 300 to 350/yd (D18531T, p. 262). 

The Water Storage Module stores water for use in the TCC, Reagent Storage and Preparation, Neutralization, Biotreatment, and Effluent Filtration Modules. Process water is received from the plant water supply and is stored in the Process Water Tank. 

BC-1 Chemical plant biotreater sludge MTBE, DIPE, ETBE and TAME, no benzene or toluene [14]... 

Various techniques exist to treat waste water biotreatment, denitrification, dephosphatation, sedimentation, flotation, etc. Depending on the waste water effluent and its composition, and the plant operation, the most appropriate techniques are selected to treat the waste water. 

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