生物滤池处理城市污水工艺中恶臭和微生物气溶胶的填料选择

采用实验室规模的生物滤池对含硫化氢、氨和微生物气溶胶的气体进行处理，并对海绵、陶粒、堆肥和空心塑料小球4种物质作为反应器填料的性能进行比较。结果表明，不同填料生物滤池对硫化氢、氨和微生物气溶胶的去除效率明显不同，去除效率从高到低的顺序依次为海绵、陶粒、堆肥和空心塑料小球生物滤池。海绵和陶粒生物滤池出气异养细菌和真菌主要以小粒径粒子为主。在同样的进气和运行条件下，堆肥填料层的压力降最大，其次是陶粒和空心塑料小球填料层，海绵填料层的压力降最小。对4种填料的性能进行综合比较，海绵和陶粒较适宜作为处理硫化氢、氨和微生物气溶胶的生物滤池填料。     

生物滴滤塔处理有机废气的填料选择研究

以含低浓度乙酸、正己烷和苯乙烯的混合有机气体模拟实际有机废气,采用实验室规模的生物滴滤塔处理有机废气,并比较了海绵、珊瑚石、陶粒和空心塑料小球4种填料的性能。结果表明:(1)生物滴滤塔启动时间最短的为海绵生物滴滤塔(约20d),其次为陶粒生物滴滤塔(约25d),启动时间较长的为珊瑚石生物滴滤塔(约35d)和空心塑料小球生物滴滤塔(约40d)。(2)在稳定运行期,不同填料生物滴滤塔对水溶性和极性较强的乙酸的去除率差异尤为明显,对正己烷和苯乙烯的去除率差异相对较小。(3)4种填料生物滴滤塔中的异养细菌数量依次为海绵>陶粒>珊瑚石>空心塑料小球。运行80d时,海绵、陶粒、珊瑚石和空心塑料小球生物滴滤塔中的异养细菌数量分别达5.9×108、4.8×108、3.6×108、3.0×108 cfu/g(以单位质量干填料计)。(4)在相同的进气流速下,4种填料生物滴滤塔的填料层压力降依次为珊瑚石>陶粒>空心塑料小球>海绵。(5)海绵和陶粒较适宜作为生物滴滤塔的填料。     

城市污水处理厂除臭生物滤池运行效果及影响因素研究

对山东某城市污水处理厂散发的恶臭气体进行除臭研究,考察了除臭生物滤池的运行效果、工艺影响因素和除臭生物滤池内微生物相特点。结果表明:(1)在进气量为828 m3/h、气体停留时间为30 s、硫化氢和氨进气质量浓度分别为0.5~28.4、0.9~34.3 mg/m3的条件下,稳定运行时,大部分时间硫化氢和氨去除率分别达98%和80%以上,而且除臭生物滤池对于进气负荷具有较强的抗冲击能力。(2)当填料含湿量为43.6%~63.4%时,硫化氢去除率在90%以上;氨去除受填料含湿量的影响较大,填料含湿量越高越利于氨的去除。(3)在处理低浓度含硫化氢和氨的恶臭气体时,生物除臭工程可以在低填料pH(3.0左右)下长期运行,并保持较高的恶臭气体去除率。(4)运行第60天后,当温度为10℃以上时,硫化氢和氨去除率几乎不受影响;第169天后,当温度降至10℃以下时,硫化氢和氨去除率均有一定程度的下降,最低分别为94.6%和79.8%。(5)除臭生物滤池稳定运行时,优势硫氧化菌主要为嗜酸性硫细菌。     

核桃壳-陶粒填料曝气生物滤池去除氨氮的研究

对核桃壳-陶粒填料曝气生物滤池(BAF)的挂膜启动和处理效果进行了研究,同时考察不同的水力负荷、气水比、填料层高度对污染物去除效果的影响。结果表明:微生物在核桃壳-陶粒填料上成功挂膜仅需21d,运行稳定后核桃壳-陶粒填料BAF的COD、氨氮去除率分别稳定在92.0%、88.3%左右;在水力负荷为0.06~0.08m3/(m2·h)、气水比为9∶1(体积比)的条件下,核桃壳-陶粒填料BAF处理效果较好且较稳定,氨氮和COD去除率可达70%以上;填料层0~15cm段为核桃壳-陶粒填料BAF去除COD的高效段,15~30cm段为去除氨氮的高效段。     

腐殖填料生物滤池氨氮降解特征

根据腐殖填料生物滤池及石英砂普通生物滤池的氨氮去除效率、表面水力负荷及微生物量差异,比较两者氨氮降解速率及比降解速率,对腐殖填料生物滤池的氨氮降解特征进行分析。结果表明,在相同运行方式及外界环境下,腐殖填料滤池表面水力负荷数倍于石英砂普通生物滤池;腐殖填料生物滤池单位体积平均氨氮降解速率高达31.5 g NH4+-N/(m3.d),是石英砂普通生物滤池的5.4倍;腐殖填料生物滤池氨氮比降解速率为4.1×10-2μg NH4+-N/(g微生物碳.d),约为石英砂普通生物滤池的4倍。腐殖填料生物滤池能负载较高的生物量,抗堵塞性能较强,系统内特异微生物对氨氮降解能力较高,是一种优良的降解氨氮的生物滤池。     

基于生物炭填料的蚯蚓生态滤池净化养殖污水的效果分析

采用蚯蚓生态滤池作为污水处理装置,探讨生物炭、秸秆、蛭石和海绵等材料经过不同组合后作为填料对蚯蚓生态滤池去除养殖污水中污染物的影响。结果表明:蚯蚓生态滤池中,生物炭和蛭石等体积混合作为填料最有利于去除养殖污水中的硝态氮和COD;生物炭和秸秆等体积混合作为填料最有利于去除氨氮和TN;生物炭和海绵等体积混合作为填料最有利于去除磷酸盐和TP。因此,生物炭与蛭石、秸秆、海绵混合作为蚯蚓生态滤池填料可能有利于净化养殖污水。     

几种腐殖填料生物滤池COD去除效能比较研究

分别采用腐殖垃圾、泥炭、煤炭等腐殖填料及河沙构筑生物滤池,处理模拟废水,比较研究其COD去除效能及降解特征,为工艺填料改性提供理论依据。几种填料的扫描电镜分析图显示腐殖垃圾及泥炭以团聚体三维空间结构为主;煤炭与河沙表面粗糙程度较小,且主要由颗粒状物质构成。稀释平板涂布法分离出各生物滤池中发挥主要作用的微生物共3种,各系统菌落数量有差异,但种类相同。3种腐殖填料生物滤池在进水有机物浓度为500 mg/L及1000 mg/L时均有较理想的有机物去除效率。3种腐殖填料生物滤池中泥炭构筑的腐殖填料生物滤池有机物比降解速率最小,因而微生物比增长速率最小,微生物增长和自身氧化最易趋向于动态平衡,对应的饱和水力渗透系数最大,滤池最不易发生堵塞,最有利于腐殖填料生物滤池长期稳定运行,证明泥炭是一种优良的生物介质。     

牡蛎壳填料浸没式生物滤池的除磷特性

探讨如何提高普通浸没式生物滤池除磷效果为目的，采用牡蛎壳为填料，通过改变水力停留时间来考察牡蛎壳和陶粒两种填料的浸没式生物滤柱对CODMn、NH4^ -N以及PO^3--P的去除特性。结果表明，与陶粒填料相比牡蛎壳填料在对PO4^3--P的去除方面具有明显的优势，牡蛎壳良好的除磷性能主要是通过生物诱导的化学沉淀来实现的。     

2种曝气生物滤池的启动比较分析

分别采用陶粒和沸石作为曝气生物滤池的填料,在相同运行参数下进行曝气生物滤池启动对比研究,分析挂膜过程中COD、NH4+-N和浊度的去除效果。试验结果表明,在平均气温为30℃的条件下,2种曝气生物滤池都能很快完成启动挂膜,陶粒曝气生物滤池所需时间为12d,沸石曝气生物滤池所需时间为15d;陶粒曝气生物滤池具有更好的COD去除效果,沸石曝气生物滤池具有更好的NH4+-N去除效果;2个滤池对浊度都能够达到95%左右的去除率。     

复合式生物除臭反应器处理城市污水处理厂恶臭气体

采用复合式生物除臭反应器处理北京某城市污水处理厂污泥浓缩池和脱水间散发的恶臭气体，研究了反应器对恶臭气体的净化效果和微生物悬浮生长区与附着生长区内的生物特性及对恶臭污染物的去除能力。该污水处理厂的恶臭气体中主要发臭物质为硫化氢和氨，除臭反应器的运行结果表明，在设备稳定运行期间，进气中硫化氢和氨的浓度分别为0.21～22.61 mg/m³和0.1～0.5 mg/m³，而出气中硫化氢浓度在0～0.06 mg/m³，氨浓度为0～0.02 mg/m³。对反应器内部测试表明，微生物悬浮生长区和附着生长区对硫化氢和氨都有一定的去除，但去除机理不同。硫化氢主要被附着生长区的嗜酸性硫细菌生物氧化,少量硫化氢在悬浮区溶于水被中性硫细菌氧化；氨主要在悬浮区靠生物硝化作用去除，少部分氨在附着区被去除，且多因化学中和作用转移到填料所含的水中。     

Long-term operation of biofilters for biological removal of ammonia

Biological removal of ammonia was investigated using two types of packing materials, compost and sludge in laboratory-scale biofilters (8l reactor volume). The aim of this study is to investigate the potential of unit systems packed with these supports in terms of ammonia emissions treatment. Experimental tests and measurements included analysis of removal efficiency, metabolic products, and results of long-term operation. The inlet concentration of ammonia applied was 20-200 mg m-3. The ammonia loading rates of 24.9-566 g NH3 m-3 d-1 to compost biofilter (BF3) and 24.9-472 g NH3 m-3 d-1 to sludge biofilter (BF4) were applied for 210 days, respectively. Removal efficiencies of the compost and sludge biofilters were in the range of 97-99% and 95-99%, respectively when the inlet concentration of ammonia was below 110 mg m-3, and the maximum elimination capacities were 288 and 243 g NH3m-3d-1, respectively. However, removal efficiency and elimination capacity of both biofilters significantly decreased as the inlet concentration increased to above 110 mg m-3. By using kinetic analysis, the maximum removal rate of ammonia, Vm, and the saturation constant, Ks, were determined for both packing materials and the value of Vm for compost was found to be larger. Periodic analysis of the biofilter packing materials showed the accumulation of the nitrification product NO3- in the operation. During the experiment, the pressure drops measured were very low. The use of both packing materials requires neither nutritive aqueous solution nor buffer solution.     

Operational characteristics of effective removal of H2S and NH3 waste gases by activated carbon biofilter

Simultaneous removal of hydrogen sulfide (H2S) and ammonia (NH3) gases from gaseous streams was studied in a biofilter packed with granule activated carbon. Extensive studies, including the effects of carbon (C) source on the growth of inoculated microorganisms and gas removal efficiency, product analysis, bioaerosol emission, pressure drop, and cost evaluation, were conducted. The results indicated that molasses was a potential C source for inoculated cell growth that resulted in removal efficiencies of 99.5% for H2S and 99.2% for NH3. Microbial community observation by scanning electron microscopy indicated that granule activated carbon was an excellent support for microorganism attachment for long-term waste gas treatment. No disintegration or breakdown of biofilm was found when the system was operated for 140 days. The low bioaerosol concentration emitted from the biofilter showed that the system effectively avoided the environmental risk of bioaerosol emission. Also, the system is suitable to apply in the field because of its low pressure drop and treatment cost. Because NH3 gas was mainly converted to organic nitrogen, and H2S gas was converted to elemental sulfur, no acidification or alkalinity phenomena were found because of the metabolite products. Thus, the results of this study demonstrate that the biofilter is a feasible bioreactor in the removal of waste gases.     

Microbial degradation of livestock-generated ammonia using biofilters at typical ambient temperatures

The purpose of this research was to neutralize livestock-generated ammonia by using biofilters packed with inexpensive inorganic and organic packing material combined with multicultural microbial load at typical ambient temperatures. Peat and inorganic supporting materials were used as biofiltration matrix packed in a perfusion column through which gas was transfused. Results show the ammonia removal significantly fell in between 99 and 100% when ammonia concentration of 200 ppmv was used at different gas flow rates ranged from 0.030 to 0.060 m3 h(-1) at a fluctuating room temperature of 27.5 +/- 4.5 C (Mean +/- SD). Under these conditions, the emission concentration of ammonia that is liberated after biofiltration is less than 1 ppmv (0.707 mg m(-3)) over the period of our study, suggesting the usage of low-cost biofiltration systems for long-term function is effective at wider ranges of temperature fluctuations. The maximum (100%) ammonia removal efficiency was obtained in this biofilter was having an elimination capacity of 2.217 g m(-3) h(-1). This biofilter had high nitrification efficiencies and hence controlled ammonia levels with the reduced backpressure. The response of this biofilter to shut down and start up operation showed that the biofilm has a superior stability.     

Fungal biofilters for toluene biofiltration: evaluation of the performance with four packing materials under different operating conditions

Packing materials play a key role in the performance of bioreactors for waste gas treatment and particularly in biofilter applications. In this work, the performance of four differently packed biofilters operated in parallel for the treatment of relatively high inlet concentration of toluene was studied. The reactors were compared for determining the suitability of coconut fiber, digested sludge compost from a waste water treatment plant, peat and pine leaves as packing materials for biofiltration of toluene. A deep characterisation of materials was carried out. Biological activity and packing capabilities related to toluene removal were determined throughout 240 days of operation under different conditions of nutrients addition and watering regime. Also, biofilters recovering after a short shutdown was investigated. Nutrient addition resulted in improved removal efficiencies (RE) and elimination capacities (EC) of biofilters reaching maximum ECs between 75 and 95 g m(-3)h(-1) of toluene. In the first 80 days, the pH decreased progressively within the reactors, causing a population change from bacteria to fungi, which were the predominant decontaminant microorganisms thereafter. All reactors were found to recover the RE rapidly after a 5 days shutdown and, in a maximum of 7 days, all reactors had been completely recuperated. These results point out that fungal biofilters are a suitable choice to treat high loads of toluene. In general, coconut fiber and compost biofilters exhibited a better performance in terms of elimination capacity and long-term stability.     

Biological treatment process of air loaded with an ammonia and hydrogen sulfide mixture

The physico-chemical characteristics of granulated sludge lead us to develop its use as a packing material in air biofiltration. Then, the aim of this study is to investigate the potential of unit systems packed with this support in terms of ammonia and hydrogen sulfide emissions treatment. Two laboratory scale pilot biofilters were used. A volumetric load of 680 g H2S m(-3) empty bed day(-1) and 85 g NH3 m(-3) empty bed day(-1) was applied for eight weeks to a unit called BGSn (column packed with granulated sludge and mainly supplied with hydrogen sulfide); a volumetric load of 170 g H2S m(-3) empty bed day(-1) and 340 g NH3 m(-3) empty bed day(-1) was applied for eight weeks to the other called BGNs (column packed with granulated sludge and mainly supplied with ammonia). Ammonia and hydrogen sulfide elimination occur in the biofilters simultaneously. The hydrogen sulphide and ammonia removal efficiencies reached are very high: 100% and 80% for BGSn; 100% and 80% for BGNs respectively. Hydrogen sulfide is oxidized into sulphate and sulfur. The ammonia oxidation products are nitrite and nitrate. The nitrogen error mass balance is high for BGSn (60%) and BGNs (36%). This result could be explained by the denitrification process which would have occurred in anaerobic zones. High percentages of ammonia or hydrogen sulfide are oxidized on the first half of the column. The oxidation of high amounts of hydrogen sulfide would involve some environmental stress on nitrifying bacterial growth and activity.     

Operational Characteristics of Effective Removal of H2S and NH3 Waste Gases by Activated Carbon Biofilter

Abstract

Simultaneous removal of hydrogen sulfide (H₂S) and am- gases. monia (NH₃) gases from gaseous streams was studied in a biofilter packed with granule activated carbon. Extensive studies, including the effects of carbon (C) source on the growth of inoculated microorganisms and gas removal efficiency, product analysis, bioaerosol emission, pressure drop, and cost evaluation, were conducted. The results indicated that molasses was a potential C source for inoculated cell growth that resulted in removal efficiencies of 99.5% for H₂S and 99.2% for NH₃. Microbial community observation by scanning electron microscopy indicated that granule activated carbon was an excellent support for microorganism attachment for long-term waste gas treatment. No disintegration or breakdown of biofilm was found when the system was operated for 140 days. The low bioaerosol concentration emitted from the biofilter showed that the system effectively avoided the environmental risk of bioaerosol emission. Also, the system is suitable to apply in the field because of its low pressure drop and treatment cost. Because NH₃ gas was mainly converted to organic nitrogen, and H₂S gas was converted to elemental sulfur, no acidification or alkalinity phenomena were found because of the metabolite products. Thus, the results of this study demonstrate that the biofilter is a feasible bioreactor in the removal of waste gases.     

Backfitting Electrostatic Precipitators: Gas Velocity and Reliability Considerations

Abstract

The kinetic behavior of the toluene biofiltration process was investigated in this research. Toluene was used as a model compound for less water-soluble gas pollutants. The limiting factor in the overall toluene biofiltration process was determined by analyzing the effectiveness factor of the biofilm along the biofilter. Experiments were conducted in three laboratory-scale biofilters packed with mixtures of chaff/compost, D.E. (diatomaceous earth)/compost and GAC (granular activated carbon)/compost, respectively. A mathematical model previously proposed was verified in this study as being applicable to these biofilters packed with different filter materials. Both the experimental and theoretical results confirmed that the biodegradation rate along the biofilter followed the zero order, fractional order to first order kinetics as toluene concentration decreased. Moreover, at higher toluene concentration, biodegradation rate and mass flux of toluene were lower near the bottom of the biofilter due to substrate inhibition. Analysis of the effectiveness factor indicated that biofiltration of a less soluble compound such as toluene should not be operated at high gas flow rates (low gas residence times) due to the mass transfer limitation of such a system. At an approximate constant inlet toluene concentration of 0.9 g/m³, the toluene removal efficiency in these three biofilters would drop below 90% when the gas residence time decreased to 2.5, 2.5, and 2.0 min, respectively.     

Gaseous ammonia uptake in compost biofilters as related to compost water content

Sewage sludge and yard waste compost were used as biofilter materials and tested with respect to their capacity for removing ammonia from air at different water contents. Ammonia removal was measured in biofilters containing compost wetted to different moisture contents ranging from air dry to field capacity (maximum water holding capacity). Filters were operated for 15 days and subsequently analyzed for NH3/NH4+, NO2-, and NO3-. The measured nitrogen species concentration profiles inside the filters were used to calculate ammonia removal rates. The results showed that ammonia removal is strongly dependent on the water content in the filter material. At gravimetric water contents below 0.25 g H2O g solids(-1) for the yard waste compost and 0.5 g H2O g solids(-1) ammonia removal rates were very low but increased rapidly above these values. The sewage sludge compost filters yielded more than twice the ammonia removal rate observed for yard waste compost likely because of a high initial concentration of nitrifying bacteria originating from the wastewater treatment process and a high airwater interphase surface area that facilitates effective ammonia dissolution and transport to the biofilm.