Treatment Of Antibiotic Wastewater By A/O-MBBR Process

It is the present sewage treatment important problems in the development of the industryto upgrade existing wastewater treatment process in situ, and improve the removal rate ofnitrogen and phosphorus and Persistent Organic Pollutants (POPs), and it is also the effectivemethod to improve water environmental quality in our country. Moving Bed Biofilm Reactor(MBBR) owns the main advantages of activated sludge and biofilm, it has the characteristicsof good treatment effect, strong capacity of anti shock loading and low temperature stableoperation. MBBR procss could effectively improve the sewage treatment plant effluentquality through in situ transformation, and it is an effective way to upgrade and reconstructwastewater treatment plant. Researches about the process at this stage are more concentratedon the suspended packing dosing ration and its removal rate, removal mechanism of nitrogenand phosphorus, etc. Researches on optimization of process parameters, steady operationand treatment performance of wastewater containing POPs such as tetracycline arelittle.Therefore, it has become a new focus that study on treatment performance optimizationof complex water of MBBR system，in the face of sewage wastewater impact.This study was based on the simulated wastewater as treatment object, by constructingand starting the anaerobic/aerobic MBBR technology laboratory system, investigating processefficiency and effect law of the anaerobic/aerobic MBBR system for removing pollution suchas Chemical Oxygen Demand (COD), ammonia nitrogen and total phosphorus,and to researchprocess characteristics under the condition of start-up and steady running.During steady stateconditions, it was put forward to further promote MBBR technology in the application ofsewage plant via providing technical reference in renovation project, by discussing theprocess efficiency of adding antibiotics in anaerobic/aerobic MBBR system, the performanceand characteristics of antibiotic wastewater treated by A/O-MBBR process, when simulationwater was added a certain amount and kinds of antibiotics.The research results showed that, the A/O-MBBR system had good resistance to impactload capacity and operation stability at low temperature. The parameters as temperature,influent concentration of COD and ammonia nitrogen and other reactor conditions had littleeffect on the performance of A/O-MBBR system. When the reaction temperature rose gradually from10~15℃to30~35℃, theremoval rate of COD did not change significantly, while that of ammonia nitrogen showeda trend of decreased after first increased, but the variation was very small.It would show thebest treatment effectiveness at20~25℃, the removal rate of COD was83.34%, the ammonianitrogen was90.46%. Under the condition of low temperature, the A/O-MBBR system hadstill ability to maintain certain COD and ammonia nitrogen removal, it had good operationperformance.Concentration of the organic matter in water increased from200mg/L to500mg/L, whileammonia nitrogen concentration increased from50mg/L to140mg/L, the COD removal ratewas without apparent changes, and the ammonia nitrogen removal rate decreased after firstlyincreased.When the dosage rate of reactor packing was30%, Hydraulic Retention Time (HRT)was8hour, the temperature was20~25℃, COD concentration was350~400mg/L, influentammonia concentration was80mg/L, effluent quality of A/O-MBBR process conformed tothe “Urban Sewage Treatment Plant Pollutant Discharge Standard (GB18919-2002)” A gradeeffluent standards.By adding antibiotics under steady state, it had inhibited the treatment efficiency ofA/O-MBBR process, influenced the activity of microorganism in the reaction system, thus thepollutants removal rate decreased. When tetracycline added into the water was50μg/L, theremoval rate of COD decreased from86.57%to76.3%, decreased by about10%; the removalrate of ammonia is reduced from88.53%to69.45%,decreased by about17%; the totalphosphorus removal rate decreased from74.55%to54.4%, decreased by about20%; whenthe concentration of tetracycline in influent water increased to200μg/L, the removal rates ofCOD, ammonia nitrogen and phosphorus were59%,55.65%and43%respectively, theremoval rate drop slightly. When the mixture of antibiotics added into the water was50μg/L,the removal rate of COD decreased from86.57%to60.57%, decreased by about26%; theremoval rate of ammonia is reduced from88.53%to61.57%, decreased by about27%; thetotal phosphorus removal rate decreased from74.55%to49.3%, down range of about25%;when the concentration of mixed antibiotics increased to200μg/L, COD, ammonia nitrogenand total phosphorus removal rate were53.94%,49.91%and35.54%, the decline was notobvious.In the process of antibiotic concentration increasing, treatment efficiency of A/O-MBBR process was continuous declined, removal rate of ammonia nitrogen andphosphorus changed more greatly, while the removal efficiency of COD was relativelystable.When the concentration of tetracycline in water was50μg/L, the effluent qualitymet the “Urban Sewage Treatment Plant Pollutant Discharge Standard (GB18919-2002)” Bgrade effluent standards; When mixed antibiotic concentration in the water was50μg/L, onlyconcentration of ammonia nitrogen in the effluent met the “Urban Sewage Treatment PlantPollutant Discharge Standard (GB18919-2002)” B grade effluent standards, that of COD andtotal phosphorus was with the “Urban Sewage Treatment Plant Pollutant Discharge Standard(GB18919-2002)” the three grade effluent standard.A/O-MBBR process reached steady state after the startup, the pollutants removalefficiency were stable, the color of activated sludge presented tan, microbial activity was good,the sludge sedimentation rate was around15%. However, after antibiotics was added intothe reactor, activated sludge color changed first of all. With increasing of antibioticsconcentrations, the color of sludge gradually became black, microbial activity and amountreduced such as Vorticella, fiber and other insects sessile ciliates gradually.When theconcentration of mixed antibiotics increased to500μg/L, suspended activated sludgefilamentous bacteria propagated, structure of sludge loose, sludge settling ratio could reach50%~60%, activity of the sludge was poor, the entire reactor smelled fishy. The activity ofactivated sludge microbial decreased significantly, the removal of pollutants in the influentwas removed mainly by the biofilm attached to suspended packing in the A/O-MBBRprocess.