Modeling of the denitrification/anaerobic digestion process of salmon fishery wastewater in a biofilm tubular reactor

The literature has paid scarce attention to the modeling of the denitrification-anaerobic digestion process in packed bed biofilm tubular reactors used to treat wastewater. The present study obtained a steady-state model for industrial salmon fishery wastewater treatment in a biofilm tubular reactor, including pH as a variable and the effect of biomass on hydrolysis. The axial profile of the reactor components and process efficiency were predicted with deviations below 6%. The optimal operating zone for the process was found at hydraulic retention time (HRT)>1.5d and inlet protein concentration (S(prot,0))<3000 mgTOCL(-1). Based on our results, we concluded that the removal of organic matter and nitrogen compounds depended mainly on HRT. The effluent pH was mainly affected by the C/N ratio, where a decrease increases pH. Organic matter removal was related with the anaerobic digestion process, while denitrification influenced mostly nitrate and nitrite removal.     

Anaerobic treatment of sulfate-rich wastewater in an anaerobic sequential batch reactor (AnSBR) using butanol as the carbon source

Biological sulfate reduction was studied in a laboratory-scale anaerobic sequential batch reactor (14 L) containing mineral coal for biomass attachment. The reactor was fed industrial wastewater with increasingly high sulfate concentrations to establish its application limits. Special attention was paid to the use of butanol in the sulfate reduction that originated from melamine resin production. This product was used as the main organic amendment to support the biological process. The reactor was operated for 65 cycles (48 h each) at sulfate loading rates ranging from 2.2 to 23.8 g SO(4)(2-)/cycle, which corresponds to sulfate concentrations of 0.25, 0.5, 1.0, 2.0 and 3.0 g SO(4)(2-) L(-1). The sulfate removal efficiency reached 99% at concentrations of 0.25, 0.5 and 1.0 g SO(4)(2-) L(-1). At higher sulfate concentrations (2.0 and 3.0 g SO(4)(2-) L(-1)), the sulfate conversion remained in the range of 71-95%. The results demonstrate the potential applicability of butanol as the carbon source for the biological treatment of sulfate in an anaerobic batch reactor.     

处理BPA模拟废水的SBR工况参数对污泥有机毒性的影响研究

在处理双酚A(BPA)模拟废水的序批式活性污泥系统(SBR)反应器中,保持进水COD含量均为300 mg·L-1左右,通过改变水力停留时间HRT从12~8 h,污泥龄SRT从20~10 d,考察污泥有机毒性和其他水质指标的变化.试验分析了空白组和40 mg·L-1初始浓度BPA对照组在不同工况条件下周期末出水COD值、污泥有机毒性分布规律以及稳定期单周期内COD值和污泥有机毒性的变化趋势.结果表明,缩短水力停留时间和污泥龄有利于活性污泥降解BPA,并消减稳定期污泥的有机毒性;出水COD稳定在50 mg·L-1左右,且水相和泥相均无BPA残留.在应用PCR-DGGE技术分析SBR系统内微生物菌群多样性和不同样品间的相似性过程中,得出污泥总毒性抑制率与微生物多样性呈负相关性关系,进水成分的不同和运行参数改变是导致污泥总毒性差异的主要原因.     

实际污水培养好氧颗粒污泥及其特性研究

采用实际城市污水在序批式反应器(SBR)中试装置中成功培养出好氧颗粒污泥.颗粒污泥的沉降速率>21 m·h-1,显示了良好的沉降性能.颗粒污泥对化学需氧量(COD)、氮(N)、磷(P)具有同步去除的能力.在3 h的运行周期中,反应器出水COD<50 mg·L-1,氨氮(NH+4-N)<5.0 mg·L-1,总氮(TN)<15 mg·L-1,对TN和总磷(TP)的去除率达到50%.采用共聚焦激光扫描显微镜(CLSM)对好氧颗粒污泥的结构分析表明,好氧颗粒污泥的胞外多聚物(EPS)在整个颗粒污泥中均匀地分布,构成颗粒污泥的骨架.对颗粒污泥的X射线衍射(XRD)分析显示,在好氧颗粒污泥的内部存在许多无机矿物质,在颗粒污泥形成初期,废水中的无机成分可能具有"晶核"的作用.     

Digestion performance and microbial community in full-scale methane fermentation of stillage from sweet potato-shochu production

Sweet potato shochu is a traditional Japanese spirit produced mainly in the South Kyushu area in Japan. The amount of stillage reaches approximately 8 × 105tons per year. Wastewater mainly containing stillage from the production of sweet potato-shochu was treated thermophilically in a fullscale treatment plant using fixed-bed reactors(8 reactors × 283 m3). Following the addition of Ni2+ and Co2+, the reactors have been stably operated for six years at a high chemical oxygen demand(COD) loading rate of 14 kg/(m3·day). Analysis of coenzyme content and microbial communities indicated that similar microbial communities were present in the liquid phase and on the fiber carriers installed in reactors. Bacteria in the phyla Firmicutes as well as Bacteroidetes were dominant bacteria, and Methanosarcina thermophila as well as Methanothermobacter crinale were dominant methanogens in the reactors. This study reveals that stillage from sweet potato-shochu production can be treated effectively in a full-scale fixed-bed reactor under thermophilic conditions with the help of Ni2+and Co2+. The high diversity of bacterial community and the coexistence of both aceticlastic and hydrogenotrophic methanogens contributed to the excellent fermentation performance.     

零价铁自养反硝化过程活性污泥矿化及解决措施

本研究通过接种生活污水处理厂活性污泥,在升流式厌氧反应器内启动了零价铁还原硝酸盐的反应,经过52d的运行后实现氮去除速率29.3 g·(m~3·d)~(-1).针对运行过程中形成的三价铁及铁氧化物对污泥的包裹,致使污泥矿化,导致活性降低的问题,进行了流加污泥和改变回流两种防矿化方式的可行性研究.采用流加方式,经过22 d运行,硝酸盐氮转化速率在33.0 g·(m~3·d)~(-1)左右,出水亚硝酸盐氮平均浓度16.50 mg·L~(-1),此两者和矿化时期相比均无较大变化,而出水氨氮平均浓度从12.38 mg·L~(-1)下降到3.58 mg·L~(-1),氮去除速率从9.9 g·(m~3·d)~(-1)恢复至15.0 g·(m~3·d)~(-1),生物反应减弱了化学还原硝酸盐过程;采用改变回流方式,反应柱外部设置回流池,利用回流池上部水进行水力循环和上升冲刷,将生成的三价铁及铁氧化物随出水流出并沉积在外部回流池内,在上升流速3.49 m·h-1的条件下,转化硝酸盐对应生成的三价铁量有大约58%通过回流沉淀在外部回流池内,硝酸盐氮反应速率在34.3 g·(m~3·d)~(-1),出水亚硝酸盐氮、氨氮浓度分别为0.22 mg·L~(-1)、0.75mg·L~(-1),未出现氨和亚硝酸盐的大量积累,实现氮去除速率在33.4 g·(m~3·d)~(-1),实现了长期运行中污泥矿化问题的解决.对比两种方式,从处理效果看改变回流模式处理污泥矿化问题优于污泥流加方式.     

双驱动反应器中热钾碱吸收二氧化碳的动力学研究

采用双驱动反应器研究了热钾碱吸收二氧化碳的反应动力学,根据双膜理论,应用CO_2-H_2O体系,实验首先对气相传质过程进行了研究,结果表明:当气相体积流量为80 m L·min~(-1)时,气相搅拌速度在100 r·min~(-1)时可认为气膜阻力消去.通过改变液相搅拌转速,研究了液相传质系数kL变化规律,获得了k_L的无因次关联式.根据热钾碱吸收CO_2反应机理,获得了宏观动力学方程,并结合溶液的非理想性,对速率方程中的浓度效应进行了校正,通过实验测定并进行了模型参数估值,各参数分别为:表观活化能E_(ob)=21.9308 k J·mol~(-1),表观反应级数n=0.1399,表观指前因子K'_0=1.1908×10~(-4)mol·m~(-2)·s~(-1)·Pa~(-1).在此基础上,通过计算获得了热钾碱吸收CO_2的本征动力学方程,各模型参数分别为:本征反应活化能E=59.57 k J·mol~(-1),指前因子k_0=2.1802×1011m~3·mol~(-1)·s~(-1).为进行整个过程反应机制的判断,计算了膜内转化系数γ,结果表明该值远大于2,可知CO_2吸收为快速反应过程,反应主要集中在膜内完成,并由此可知工业反应器选型应采用比相界面积较大的填料塔为优.     

Sediment pollution characteristics and in situ control in a deep drinking water reservoir

Sediment pollution characteristics, in situ sediment release potential, and in situ inhibition of sediment release were investigated in a drinking water reservoir. Results showed that organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) in sediments increased from the reservoir mouth to the main reservoir. Fraction analysis indicated that nitrogen in ion exchangeable form and NaOH-extractable P (Fe/Al-P) accounted for 43% and 26% of TN and TP in sediments of the main reservoir. The Risk Assessment Code for metal elements showed that Fe and Mn posed high to very high risk. The results of the in situ reactor experiment in the main reservoir showed the same trends as those observed in the natural state of the reservoir in 2011 and 2012; the maximum concentrations of total OC, TN, TP, Fe, and Mn reached 4.42 mg/L, 3.33 mg/L, 0.22 mg/L, 2.56 mg/L, and 0.61 mg/L, respectively. An in situ sediment release inhibition technology, the water-lifting aerator, was utilized in the reservoir. The results of operating the water-lifting aerator indicated that sediment release was successfully inhibited and that OC, TN, TP, Fe, and Mn in surface sediment could be reduced by 13.25%, 15.23%, 14.10%, 5.32%, and 3.94%, respectively.     

移动床生物膜反应器净化模拟水产养殖废水的研究

采用移动床生物膜反应器（MBBR）净化模拟水产养殖废水.结果表明,MBBR净化模拟水产养殖废水效果良好.在水力停留时间（HRT）为8 h,DO为2.0~3.0 mg·L^-1的条件下,反应器启动迅速、运行稳定,能使COD和氨氮去除率均达到80%以上,TP去除率达到50%左右;有机负荷为（0.76±0.03）kg·m^-3·d^-1时,TN及氨氮去除效果最好,去除率分别达到71.73%及98.42%.为达到良好的TN去除效果,有机负荷不宜低于0.5 kg·m^-3·d^-1;DO为（3.00±0.25）mg·L^-1时,TN去除效果最好,最有利于同步硝化反硝化;为保持较高的氨氮去除效率,并减少亚硝态氮积累,DO浓度不应低于2.0 mg·L^-1;HRT过短会使氨氮去除效率降低,且可能出现亚硝态氮积累;采用序批式进水运行方式,对TP的去除效果优于连续进水方式,但运行周期后半段会出现亚硝态氮积累,对鱼类产生危害.     

基于微气泡曝气的生物膜反应器处理废水研究

微气泡曝气有助于强化氧传质过程,在废水好氧生物处理中具有潜在的应用优势;生物膜反应器是应用微气泡曝气的可行工艺形式.本研究在生物膜反应器中采用SPG膜微气泡曝气处理模拟生活废水,探讨反应器连续运行过程中,SPG膜空气通透性、溶解氧变化、污染物去除效果及氧利用情况.结果表明,基于SPG膜微气泡曝气的生物膜反应器能够实现长期连续稳定运行,是微气泡曝气与废水好氧生物处理结合的可行方式.SPG膜表面性质及膜孔径影响其空气通透性,疏水性膜的空气通透性优于亲水性膜;膜孔径越大,空气通透性越好.一定的SPG膜空气通量下,反应器内的溶解氧浓度主要受有机负荷影响.SPG膜微气泡曝气生物膜反应器较优的COD处理负荷(以SPG膜面积计算)为6.88 kg·(m2.d)-1.氨氮的去除主要受溶解氧浓度及生物膜内氧扩散传质的影响,在高有机负荷下生物膜内出现同步硝化反硝化.微气泡曝气的氧利用率显著高于传统曝气方式,在优化的运行条件下,氧利用率可以接近100%.