COMPLIANCE INFO_PRE 2019 - Laserfiche WebLink

Home Browse Search

f+„4.',ti �, +fir..: ..' •- •;�,�,�.a� � r. Engineelrng=EN('V'IR4NMENTA L Comparing TreatmentMethods For it O wastewaterY Separation of oils from small i quantities of wastewater reduces disposal costs i DOUGLAS PETERSON, P&H Systems, MontourstWle, P.4 Petroleurn products such as oils, remove gross oil contamination are inex- greases, and related additives are pensive and simple to operate. Fixed blade common components of industrial or moving belt skimmers remove only the waste streams. These substances, whether oil that has floated to the surface and oil released as a component in effluent or sim- concentrations in. the output effluent are ply dumped on plant premises, can cause usually in excess of 100 ppm, too high a serious on-site environmental damage. concentration for discharge to a sewer sys- Separating oils from wastewater is required tem without further treatment. Skimmers in most industries. Although large quanti- do not remove soluble oils', emulsified oils, ties,as used in plant processes, are seldom or tallows.Since skimmers rely on natural overlooked, smaller amounts from other oillwater separation for their operation, plant systems can be. Wastewater from flow-through rate must be low(Fig. 1). manual washing operations, steam clean- ers, and effluent from air compressors are Skimmer-Filter Units in this second category. Oily wastewater is piped directly to these Waste oils are of many types. They in- units from a temporary.;storage tank or clude petroleum-based lubricants, polygly- from a prime source;"such''as an air com- cols,polyalphaolefins(PAOs),diesters,and pressor. If the effluent is fed under pres- tallows. Each lubricant provides its own sure,skimmer-filter units"usually include a �. . ;` problems for separation from the water car- depressurizing chamber which"reduces the ner. Some oils emulsify, others won't. flow to a slow-moving stream::The effluent Some lubricants are truly soluble in water, then moves to a separate chamber where it form a strong molecular bond with water, remains while the oil floats to the surface. and are extremely difficult to separate. Generally,the water moves under a baffle, All states have laws which regulate the then through an actuated charcoal filter to flow of wastewaters to the land or waters, remove the remaining oil, and is drained and with some exceptions, the maximum off. The separated oil.is drained off at the oil content of any water released must be top skimming area(Fig.2): greater than 10 ppm. The charcoal filter units can reduce the A wide variety of devices are available. oil content of the water to as low as 5 ppm. The equipment can be divided into two They are also relatively inexpensive, and general groups depending on their basic op- are available in a variety of capacities. eration.Some units separate and collect the Disadvantages in the use of skimmer-fil- oil from the oil/water waste stream.Others ter units are inflow to units must be con- remove the water from the oil/water waste trolled to prevent flooding, most units of _ stream. Volumetric capacities, technical this type do not capture all soluble or syn- corn plexity, and costs of this equipment thetic oils,charcoal filters require periodic vary widely. When installed, operation of replacement,and used charcoal filters must this equipment is subject to local.water an- be disposed of by appy"oved methods. d/or air pollution control regulations. Absorber Systems" Skimmer Tanks The basic concept behind these systems Simple skimmer tanks that are used to is similar to that of skimmer units.As efflu- en.of AuT cur-iueeolun_uaoru A +aa v FILE 7020