Research On Upgrading And Reconstruction For Wastewater Treatment Of A Acrylic Fiber Plant

China is the world’s largest acrylic fiber production and consumption country, Thewastewater of Acrylic production process has much harmful effects on the environment. Thispaper studies the characteristics of wastewater from acrylic fiber enterprises in NortheastChina, analyzes the existing problems of the wastewater treatment process, proposes the mostsuitable pretreatment process, for the transformation of the existing treatment processes ofwastewater treatment, solve the problem of acrylic wastewater is the high COD and ammonianitrogen after treatment, to reach the industry discharge standard.Acrylic fiber wastewater contains more oligomers and a lot of suspended particles, easyto deposit on the membrane surface, reducing microbial contaminants in wastewater andsurface area in contact, causing adverse effects on biochemical treatment. Pretreatment ofsewage treatment plant is now used mainly coagulation-flotation process,after the raw waterby flotation treatment, COD removal is generally not more than10%,the removal ofammonia is also not good. In this study, acrylic fiber wastewater treatment using activatedsludge adsorption technology, according to the results of Smith test,sludge and sewage withinthe initial5-15min after mixing, the COD in wastewater can appear removal rate isextraordinary, but unfavorable treatment soluble organic wastewater.Acrylic fiber wastewatercontains high concentrations of nonbiodegradable material and suspended particles, the waterquality suitable for activated sludge adsorption technology was used as pretreatment process.Activated sludge has the effect of flocculant, can make part of suspended solids and colloidalsewage settling down.Through a small pilot test to investigate the sludge dosage, inspectedthe sludge dosing quantity, adsorption time, the effects of the regeneration time of processing,to test the secondary settling tank sludge activated sludge. The results show that: activatedsludge and raw water based on1:1mixed daeration40min, COD and ammonia nitrogenremoval rate can reach about20%. The mud mixture to precipitate30min can achieve a goodseparation. To return sludge precipitated regeneration, restoration adsorption properties ofsludge.Sewage plant two oxidation pools use a new biological membrane method, the carrieris polyurethane foam, the carrier has good microbial immobilization effect,but the effluentCOD and ammonia nitrogen is higher, May be related to the poor operating conditions ofoxidation pool. The carrier of oxidation pond in the bench scale experiments, effects ofdissolved oxygen (DO), vector quantity, hydraulic retention time, effect of basicity andphosphorus source.The experimental results show that: the more the number of carriers, thehydraulic retention time is longer, the better the effect of water. Especially in the dosing ofsodium bicarbonate, the reactor effluent ammonia levels down to10mg/L or less; in the reactor and the introduction of efficient dosing sponge iron bacteria, the effluent CODcontent as low as200mg/L or less.Acrylic fiber wastewater is difficult to deal with industrial waste water, there is nomature technology to draw upon. Currently wastewater treatment plant has been builtstructures quantity, various pipeline is complicated, coupled with limited floor space, so thewhole site is very compact, very limited space for transformation, and the economicfeasibility of reconstruction engineering must be considered. Therefore, the guiding ideologyof this transformation is: according to the objective reality, as far as possible the use ofexisting structures, buildings and equipment, saving the project investment and reduceoperating costs.Modification of the existing treatment process for sewage plant, mainly toexisting coagulation-flotation process transformation into activated sludge adsorption-regeneration processes, building location site convenient reconstruction. In the flotation nextoxidation pond is an activated sludge process, the oxidation pond into adsorption andregeneration of activated sludge pool. There are two hydrolysis acidification pool site, sewageafter hydrolysis acidification pond after no obvious removal effect, also failed to improve thebiodegradability of the wastewater, after verification of the hydrolytic acidification tankstopped, effluent was not affected. Can put the hydrolysis acidification into oxidation pond,and two new series run, offset to transform a oxidation pond into adsorption-regeneration,insufficient pond treatment effect of oxidation. According to the results of test, adjust theoperating parameters of oxidation pond, adding the carbon source and the introduction of highefficient bacteria, can also selectively add sponge iron carrier, through the sponge iron of thedual role of micro electrolysis and catalyst to further strengthen the treatment effect ofoxidation pond.After the transformation of the existing treatment processes, the new process isequivalent to "AB" technology, A period of transformation from oxidation pool, section Brefers to using the two new oxidation pond for the depth of the wastewater biochemicaltreatment; The whole transformation process is not a new big structures, need to increase(change) part of the pipeline and pump system, if after transforming effect is not good, onlythe operation a few valve will change back to the original process. After estimating thetransformation cost about250000yuan, only to save the air flotation medicament cost, about3months can recover the investment. If wastewater plant effluent effect after improved, canreduce the amount of pollution discharged into the Songhua River, can create hugeenvironmental benefits and social benefits.