Study On The Start-up And Domestication Of Ammoniacal Nitrogen Of Sbr For Swine Wastewater Treatment

Swine wastewater abundant with COD and ammoniacal nitrogen is a kind of highconcentration organic wastewater. The amount of swine wastewater is very large and thewater quality is unsteady. It has been a serious problem how to treat swine wasetwater.However, the treatment techniques are not perfect at present. There are many difficulties, theparameter is hard to determine and the process is nontrivial to start up, for example. SBRprocess which can remove COD and NH4+-N efficiently is relatively simple and its adaptioncapacity for different waters is good. So the advantage of SBR should be played. Soresearching the process and conditions of SBR for swine wastewater treatment is of greatsignificance. The research is expected to play a role in disposaling problems causing by theincreasing number of swine wastewater, the protection of water resources and ecologicalenvironment, reducing non-point source pollution and protecting the health of human beings.First, we studied the factors affecting the start-up of SBR，including hydraulic retentiontime, feeing ratio of sludge and aeration intensity. Low concentration swine water was used inthe study. The COD removal rate after20days and the starting principle based on othereffluent water quality indexes were analyzed. Finally, we restarted the SBR under the optimalreaction condition obtained by the experiment. Second, we changed the ammoniacal nitrogenconcentration of influent to domesticate the activated sludge in the stable SBR reactor. Theadaptive mechanism of SBR process to wastewater with varied ammoniacal nitrogenconcentration was confirmed according to the variation of effluent water quality indexes intwo weeks. Also, we calculated the time for the process to come to a new stable state. The lastgroup experiment was about the study of the feeding mode. In the previous experiment, wefound that the COD and NO3-N concentration of effluent was a little high, so we modified thefeeding mode and took measure of two-step feeding. The change rule of the effluent waterquality indexes in the first eight hours of the steady state was analyzed combing the pH、ORPand DO. The conclusions of the paper are as follows:1The elapsed time for start-up of SBR shortened as HRT(ranged from3.3d to6.7d)increased, but rose up and then declined as the feeing ratio of sludge (ranged from10%to45%) grew and the same as aeration intensity (ranged from2L/min to4L/min). In the singlefactor design, when the HRT was6.7d, the feeing ratio of sludge was30%and the aerationintensity was3L/min, the elapsed time for SBR starting was15d,16d and15days and the removal rate of COD was84.38%,90.21%and90.80%,respectively. Consequently, we tookthe above combination as the best condition and restarted the SBR process. It was proved thatthe process approached a new steady state after14days and ran well. Besides, the removalrate of COD,ammoniacal nitrogen and phosphorus was91.43%,99.47%and76.72%. Thestart-up of SBR succeeded.2Ammoniacal nitrogen, COD and phosphorus in effluent water of SBR at steady statereached (6.37±1.70) mg/L、(409.90±77)mg/L and (7.29±0.13)mg/L, corresponding theiraverage removal rate were99.25%,84.18%and74.09%, respectively. With an increase ofinfluent concentration of ammoniacal nitrogen, the SBR was in shock state in first ten daysand reached steady state subsequently. Ammoniacal nitrogen, COD and phosphorus in SBRchanged in a wave style in shock period, while they tended to stable in steady period. Theability of denitrogenation of SBR was promoted, while the removal efficiency of COD andphosphorus were decreased at the same time in steady period. The degradable ability of CODcould be recovered by a long-term domestication with high influent concentration ofammoniacal nitrogen, and the sufficient COD concentration in feeding wastewater played animportant role in dephosphorization ability of SBR at high influent concentration ofammoniacal nitrogen. By increasing the concentrations of ammonia nitrogen gradually, weobtained a high effitioncy SBR, which could be used to treat swine manure.3The phenomena that the effluent concentration of COD and nitrate nitrogen was toohigh was improved after the feeding mode was changed. Namely, the SBR could degrade theswine water efficiently. In the two-step fed SBR, pH declinied in the period ofanaerobic/anoxic phase, but rose up and then declined in both aerobic phase.‘pH valley’indicated the end of the nitrification in aerobic phase. ORP declinied in the period ofanaerobic/anoxic phase. In this phase,‘ORP elbow’ appeared as the turning point of decliningrate, which indicated the end of denitrification. The denitrifying phosphate-accumulatingorganisms which can degrade the nitrate nitrogen and phosphorus simultaneously could beobtained in two-step feeding process.