The Influence Of Heavy Metals And Antibiotics On Treating Swine Wastewater By Sequencing Batch Biofilm Reactor

In swine wastewater, the trace contaminants such as heavy metals and antibiotics from feed additives and veterinary drugs abuse were neglected in effecting the results of the aerobic biological treatment, therefore, this experiment put the sequencing batch membrane bioreactor(Sequencing Batch Biofilm Reactor, SBBR) which is always be taken in the swine wastewater treatment and also is highly efficient to use as research objective. The main targets of this experiment are Cu( Ⅱ), Zn(Ⅱ),oxytetracycline(OTC), sulfamonomethoxine(SMM) which are widespread and relatively high-concentrated heavy metal and antibiotics in swine wastewater. This experiment will show the specific mechanism and interaction when using the SBBR treat swine wastewater [in sewage treatment effect(removal of COD, NH3-N, TP)and activated sludge(MLSS, SVI)] in there situations: separate [Cu(Ⅱ), Zn(Ⅱ), OTC,SMM], complex [Cu(Ⅱ)-Zn(Ⅱ), OTC-SMM] and associated [Cu(Ⅱ)-OTC]. The main conclusion of the study was as follows:(1) Both heavy metals [Cu( Ⅱ), Zn( Ⅱ)] and antibiotics [OTC, SMM] acting alone will have an influences on SBBR swine wastewater treatment effect, but the effects are in different ways. To wastewater treatment, the low concentration of Cu(Ⅱ), Zn(Ⅱ) play a part of promoting the treatment effect. The high concentrations exhibit inhibition, but after the adaptation and domestication of microorganism the inhibition eased. Whether high or low concentration of OTC, SMM, both of them will show inhibition and cannot show a trend of self-recovery capability.(2) For COD, NH3-N, TP and other indicators, four substances inhibitory size is as follows: OTC> SMM> Cu( Ⅱ)> Zn( Ⅱ). Inhibition size of the same substance among the different indicators is as follows: TP> NH3-N> COD. To MLSS and SVI is:SMM> OTC> Cu(Ⅱ)> Zn(Ⅱ), this phenomenon results from different mechanism of action, physical and chemical properties of OTC and SMM.(3) Different concentrations of complex Cu(Ⅱ)-Zn(Ⅱ) have the similar affects with the way of single Cu(Ⅱ), Zn(Ⅱ) to system. The complex toxic effect value of different concentrations and indictors is greater than 1, and they show antagonism.When Cu(Ⅱ) concentration constant, the higher the Zn(Ⅱ) concentration the stronger antagonism, this can be explained by point competition theory and metallothionein.(4) Different concentrations of complex OTC-SMM have the similar affects with the way of single OTC, SMM to system. The complex toxic effect value of different concentrations and indictors is greater than 1, and they show antagonism, the higher the OTC concentration the stronger antagonism. This phenomenon may be explained by OTC has stronger and faster capability of antibacterial and sterilize, and broader role band than SMM, this may obscure the SMM inhibition to some extend.(5) Different concentrations of combined Cu(Ⅱ)-OTC will effect the system, the specific phenomenon has: In the preceding period, with the growth of time the effluent quality has continued deterioration, and at the later stage it keeps constantly.When at the situation of Cu(Ⅱ)-OTC associating and the concentration of Cu(Ⅱ) at16 mg/L the effluent TP even is higher than the inlet TP. Probably because Cu(Ⅱ),OTC added to the system caused great impact to system, and they result in microbial disintegration, the originally absorptive TP had been re-released into water. With the growth of time, the MLSS and SVI have continued decrease, at the later stage have slight fluctuation. No positive correlation was shown in the influence degree between all indictors and associated Cu(Ⅱ)-OTC concentration.(6) Complex toxic effect values decrease with the growth of Cu( Ⅱ)concentration at the situation of Cu(Ⅱ)-OTC associating. This situation even cause a change between interaction relationship. When at the situation of combination and the Cu(Ⅱ) concentration at 4-8 mg/L, Complex toxic effect values of all indictors were greater than 1, show antagonism. When at 16 mg/L, Complex toxic effect values of all indictors become less than 1(except Complex toxic effect value of NH3-N slightly larger than 1, mainly because of the aeration caused stripping effect lead to a constant NH3-N removal), show a synergistic effect. All above were caused by and various complexes’ types and amount of Cu(Ⅱ) and OTC generating at different pH and heavy metal concentrations. The various complexes will have different ways of combination with microorganisms, and they caused different size of inhibition.