| For the long time,the pig farm wastewater treatment has been faced some problems about the high treatment cost,poor quality of emission,difficulty in wastewater treatment and so on.Because of the low C/TN and high concentration of ammonia niitrogen,that makes the pig farm wastewater's biochemical degradation performance poor and increases the difficulty in pig farm wastewater treatment.In recent years,the black membrane biogas tank due to the low cost has a certain effect,and widely uses in each pig farms.So the research of the black membrance biogas tank effluent has a general representative,which has a great significance to control agricultural non-point source pollution research.This paper investigates the MAP(Magnesium-Ammonium-Phosphate)and SBBR(Sequencing Biofilm Batch Reactor)process,and reasearch about the black menbrane biogas tank wastewater by various operation parameters and control conditions.The main experimental content is as follows:In MAP test,researching the effect of ammonia nitrogen removal by adding various phosphorus sources and magnesium sources,and adjusting the amount of additives,reaction time,p H,adding oxalic acid or not,etc.,to analyze a best operation condition.With the cost and the removal effect as investigation factors,to get a suitable MAP process in industical operation.In SBBR test,using the SBR process as comparison,investigate the influennce to the effect of subsequent biochemical treatment about hydraulic retention time(HRT),influent's ammonia nitrogen concentration,aeration on/off ratio,etc.and comprehensive analysis the effluent COD,ammonia notrogen,nitrate nitrogen,total nitrogen and total phosphorus as investigation factors to make sure the superiority of SBBR process in pig farm wastewater treatment.In this paper,the main conclusions are follows:(1)MAP process,that is the NH4+,Mg2+ and PO43-can produce the magnesium ammonium phosphate precipitation under the alkaline conditions to remove the ammonia nitrogen in wastewater.In the text,the calcium-magnesia phosphate ferilizer also contains magnesium and phosphate.But the soluble PO43—P content is low,that is not meeting the requirements of the MAP reaction.And the calcium-magnesia phosphate fertilizer in MAP reaction has only a 1.61% ~ 6.25% ammonia nitrogen removal rates.The calcium superphosphate as a phosphorus source in MAP,when adding amount up to 50 g/L,with magnesium sulfate or magnesium slag as a magnesium source,the effluent ammonia nitrogen is 194.78 mg/L and 214.66 mg/L.Effluent ammonia nitrogen concentration is down to about 200 mg/L,that will conform to the requirements of the subsequent biochemical treatment influent.So the calcium superphosphate is a viable option.(2)In MAP process optimization,researching the adding amount of calcium superphosphate,magnesium source and its adding amount,optimum p H,reaction time and so on.As result,with raw wastewater ammonia notrogen concentration of 435.67 mg/L,when calcium superphosphate adding amount up to 50 g/L,it can get a MAP effluent ammonia notrogen concentration down to about 200 mg/L and the ammonia nitrogen removal rate up to 55.29%.In the magnesium source selection,about the MAP effect,the magnesium sulfate is better than magnesium chloride,than magnesium slag.But considering the cost,the magnesium slag is the preferred magnesium source.In the optimum p H,found that,the optimum p H is 9.0.And the optimum reaction time is less than 24 h.(3)In the subsequent biochemical experiment,with the increasing HRT,the effluent COD concentration is between 248.57 ~ 506.27 mg/L and COD re moval rate is between 48.18% ~75.11%.Also with the increasing HRT,the ammonia nitrogen removal efficiency is from ammonia nitrogen accumulation to have a 99.73% ammonia nitrogen removal rate.About the nitrate nitrogen concentration,also has nitrate acc umlation condition in each HRT.The total nitrogen,with the increasing HRT,the TN removal rate increases from-156.63% to 84.75%.And the TP concentrations all decrease and change similar in each HRT.But also can't reach the Livestock and Poulty Breeding Industry Pollutant Discharge Standard(DB44/613-2009).In the three kinds of ammonia nitrogen concentration influent research,the change of COD concentration dose not influence by the ammonia nitrogen concentration changes.And the ammonia nitrogen concentration changes are different,from accumulation to removal under the three ammonia notrogen concentration.The nitrate nitrogen accumulation conditions are also in low ammonia nitrogen concentration influent.It can't see any relation between the total phosphorus and ammonia nitrogen concentration changes.(4)In the three kinds of aeration/non-aeration ratio research,the COD removal is better in 1:1 stages and SBBR also is better in COD removal than SBR.In ammonia nitrogen removal,the SBBR can get a better removal rate,is up to 99%.It dose not influence by the aeration/non-aeration ratio.But the SBR just can removal ammonia nitrogen in 2:1 stages.It knows that the adding filler is good for oxygen distribution and ammonia nitrogen removal in SBBR.O n the other hand,the nitrate nitrogen also accumulated and up to 243 mg/L in SBBR by 2:1 stages.It knows that the adding filler can promort ammonia nitrogen transform to nitrate nitrogen.This part,TN removal rate is-6.86% ~ 77.85%.And the TP concentratio n also can't meet the standard too.To sum up,the MAP-SBBR process can make the influent high ammonia nitrogen concentration of the subsequent biochemical treatment down to about 200 mg/L,and that can be benefit to the subsequent biochemical treatment and the shortcut nitrification reaction.When the HRT is 5d,the effluent COD concentration can fell to 273.54 mg/L and the ammonia nitrogen removal rate can up to 99.73%.But only just TP concentration can't fell to the standard(COD standard 380 mg/L;ammonia nitrogen standard 70 mg/L).This study will provide the pig farm black membtane biogas tank effluent a comprehensive treatment idea or guidance.That is conducive to the development of pig farm wastewater treatment. |
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