Ciliates in a waste stabilization pond system in Mexico

A protozoological survey was performed on a waste-stabilization pond to isolate, identify, and determine the incidence of ciliates present in these waters. The correlation between the species found and the physicochemical parameters was investigated. One hundred and eighty samples were analyzed from February 1983 to February 1984. Free-living ciliates isolated include:Carchesium polypinum Linnaeus,Vorticella microstoma Ehrenberg,Vorticella convallaria Linnaeus,Didinium balbiani Fabré-Domergue,Amphileptus claparedei Stein,Spathidium spathula Müller,Litonotus fasciola Ehrenberg,Paramecium caudatum Müller,Paramecium aurelia Ehrenberg,Tetrahymena vorax Kidder,Tetrahymena pyriformis Ehrenberg,Cyclidium glaucoma Müller,Aspidisca costata Ehrenberg, andStylonychia putrina Stokes. The performance of the pond was predominantly anaerobic. The temperature, total alkalinity, and nitrate concentration were the most variable parameters in the system studied.     

Amoebae in a waste stabilization pond system in Mexico

A protozoological survey was performed to analyze the organisms of the subphylum Sarcodina Schmarda, present in waste stabilization ponds located at Santo Tomás Atzingo, México, from March to December 1981. The amoebae isolated were identified and counted. Several physicochemical parameters were also determined and correlated with the biological data. Thirteen amoebic species were isolated and identified: one definite pathogen, Entamoeba histolytica Schaudinn; three species that have shown pathogenic strains for humans: Acanthamoeba polyphaga Page, Acanthamoeba castellanii Douglas, and Naegleria sp. (Alexeieff) Calkins; two opportunist species: Entamoeba coli (Grassi) Casagrandi and Barbagallo, and Iodamoeba bühschlii (Von Prowazek) Dobell; and seven free-living amoebae: Acanthamoeba astronyxis Ray and Hayes, Amoeba proteus (Pallas) Leidy, Hartmannella exundans Page, Hartmannella vermiformis Page, Pelomyxa palustris Leidy, Vahlkampfia avara Page, and Vahlkampfia russelli Singh. A clear correlation between the number of amoebae and the temperature and alkalinity of the system was found. The removal capacity of the ponds for E. histolytica varied from 30 to 100% during the survey. The amoebae showed a succession in space and time in the system studied.     

Boundary conditions for the waste stabilization pond

Two different solutions of the dispersed flow model of the waste stabilization pond based on two different sets of boundary conditions were compared and analyzed statistically. These solutions, used in the prediction of the coliform reduction in the pond, were based on Hulbult's and Danckwerts' sets of boundary conditions. Although Danckwerts' set of boundary conditions is more mathematically consistent than Hulbult's, the solution based on the latter is simplier. Besides, statistical analysis at the 0.01 level of significance showed that there is little to choose between the two in terms of accuracy. Also, the two solutions gave similar values of correlation coefficient, standard error, intercept and regressed slope.     

Simplified optimal design of the waste stabilization pond

A graphical method was applied to cost minimization in the waste stabilization pond subject to area, depth and efficiency constraints. The solution have the values of area, cost and depth at optimality. The paper also compared the optimal solutions for both plug-flow and completely-mixed flow models. Although the optimal depths for the design data considered was the same for the two models, the plug-flow model cost only one-fifth of that of completely-mixed flow model. The area occupied by the latter was found to be four times larger.     

A new method for dispersion number determination in waste stabilization pond

The paper presents a new method for the determination of the dispersion number in a waste stabilization pond. Requiring only the data on bacteria variation along the pond as input, this method is simple, accurate and economical compared with the conventional tracer study method. Its application in pond design and evaluation is also discussed.     

Bacterial analysis of Chromobacterium sp. and Flavobacterium sp. in a waste stabilization pond system

A survey on Chromobacterium sp. and Flavobacterium sp. was conducted in a waste stabilization pond system at Santo Tomas Atzingo, State of Mexico. For this purpose methods for the isolation and identification of Chromobacterium sp. and Flavobacterium sp. from wastewater were developed and proved to be efficient. Such methods are the result of combining and modifying a series of previously reported techniques for this genera strains, but for environments different from wastewater.     

Soil and aquatic fungi in a waste-stabilization pond system of the state of Mexico,Mexico

Twenty fungal strains were isolated from a small waste-stabilization pond system near Santo Tomás Atzingo, Mexico, using a number of plating and enrichment culture techniques. Among isolates, only Pythium sp. was aquatic. Eight fungi of interest to the plant-pathologist were recovered. Seven strains hydrolyzed casein and four amylum. All isolates, with the exception of Phoma sp., formed colonies in culture media with surfactant levels of 10 mg L^?1. Eleven strains proved to be acid-formers.     

A comparison between the spatial distribution pattern of flagellates and some physicochemical parameters in a waste stabilization pond

Protozoological and physicochemical analyses were performed in a waste stabilization pond at Sto. Tomas Atzingo, a small town near Mexico City, in order to discern the internal dynamics of the pond water through the study of the spatial distribution pattern of flagellates and the parallel water volume distribution pattern of some selected physicochemical determined parameters. The statistical method applied to the data obtained was by cluster analysis. The results showed a slight trend to heterogeneity in the system, when it was evaluated through the physicochemically determined parameters. On the other hand, the spatial distribution pattern of the flagellates pointed out a remarkable heterogeneity in the pond. In systems like the one studied where the main feature is an organic matter overload, such a difference in findings indicates a low correlation between the biological parameters, in this case the flagellates, and the physicochemical variables, that should be considered when evaluating the water quality of such systems, either through the physicochemical, the biological or both scopes.     

Dispersion number determination in waste stabilization ponds

The measurement and determination of the dispersion number in ponds is usually based on the one-dimensional diffusion equation. This paper shows that since the criterion underlying the application of this equation is not often satisfied, great error may be introduced in the determination of the dispersion number(d). The effect of this on the prediction of the bacteria reduction is also discussed.     

Application of stabilization pond for purification of textile wastewater in Esfahan,Iran

Two experimental ponds, with an effective volume of 2 m3 each, were constructed in a workshop at the textile plants to investigate the potential for a stabilization pond for purification of textile wastewater. Parametric analysis of pH, temperature, turbidity suspended solids, total suspended solids, DO, BOD, COD, N, and algae was carried out on the influent and the effluent according to the procedures recommended by the standard methods (APHA, 1971). Considering the results obtained from tests after daily observations, the application of an oxidation pond for treatment of textile wastewaters in the winter time was not promising. The ponds had a little activity in aerobic condition. In other seasons the ponds were efficient and the removal of BOD, COD, and N was 81, 78, 72% respectively, with a loading rate of 7.950 g BOD m^?2 day^?1 and detention time of 20 days. The ponds were usually saturated and sometimes super-saturated with dissolved O₂. The experimental ponds were put to work in series for BOD, COD, and N removal observation. The removal did not improve compared with a single pond and algae concentration was noticeably reduced in the effluent.     

凹凸棒土-稳定塘工艺提高严寒地区农村生活污水处理效果

针对严寒地区农村生活污水处理面临的低效率、高能耗、排水不达标的典型问题,首次提出凹凸棒土—稳定塘模式处理严寒地区农村生活污水。该研究创新的通过PLC（programmable logic controller）自控试验设计,考察在低温10℃条件下工艺的最优运行参数,经过平行对比试验研究凹凸棒土作为载体填料对低温生活污水处理效果的影响。结果表明,pH值在7.2～7.8之间,兼性塘水力停留时间为4d,好氧塘的水力停留时间与曝气时间分别为36、4 h时,工艺对化学需氧量（chemical oxygen demand,COD）、氨氮（ammonia nitrogen,ammonia-N）、总磷（total phosphorus,TP）的平均去除率分别为91.5%、87.7%、84.1%,平均出水质量浓度分别为35.6、4.5、1.0 mg/L,满足国家二级排放标准,而单一式稳定塘工艺的低温生活污水处理效果显著降低,COD、氨氮、TP的去平均去除率分别降低了3.6%、6.0%、4.7%。凹凸棒土—稳定塘工艺可以有效的去除严寒地区农村生活污水中有机物及氮磷污染物,对削减农村水污染、降低水环境负荷及改善农村生态环境具有重要作用,同时也为凹凸棒土的应用拓展了新的方向。     

Kinetics and economics of anaerobic digestion of animal waste

Disposal of animal waste represents a severe environmental problem, particularly in areas such as cattle feedlots where livestock are concentrated. Animal waste can be converted to CO₂ and CH₄ by the autocatalytic process of anaerobic fermentation. A scheme, based upon this process, for the disposal of the waste from a large feedlot is presented. The design of this process is based on kinetic data from the literature which are fitted to a kinetic model including diffusional resistances. Sale of the CH₄ provides an economic incentive for this process and a return on investment of 23 % yr^?1 appears possible for a large feedlot.     

餐厨垃圾高温厌氧消化接种物的驯化研究

研究不同投料方式对餐厨垃圾高温厌氧消化接种物产气活性的影响,探求餐厨垃圾高温厌氧消化接种物的最佳驯化方法。在55℃条件下,采用不同方式对厌氧污泥进行驯化作为餐厨垃圾高温厌氧消化的接种物,观察了驯化前后污泥中微生物菌群的形态结构,考察了驯化过程中污泥pH值和VFA(挥发性脂肪酸)浓度的变化,并且比较了驯化后污泥的产气活性,结果表明：污泥经过添加一定量的餐厨垃圾驯化培养后,其微生物菌群形态由球形演变为单一的杆状菌体,且分布较分散,产气活性也有所提高,其中每日投加餐厨垃圾2.5 g(污泥质量的0.5％),驯化2     

Chemical stabilization of soil organic nitrogen by phenolic lignin residues in anaerobic agroecosystems

This review summarizes independent reports of yield decreases in several agricultural systems that are associated with repeated cropping under wet or submerged soil conditions. Crop and soil data from most of these agroecosystems have led researchers to attribute yield decreases to a reduction in crop uptake of N mineralized from soil organic matter (SOM). These trends are most evident in several long-term field experiments on continuous lowland rice systems in the Philippines, but similar trends are evident in a continuous rice rotation in Arkansas, USA and with no-till cropping systems in North American regions with cool, wet climatic conditions in Spring. Soil analyses from some of these systems have found an accumulation of phenolic lignin compounds in SOM. Phenolic compounds covalently bind nitrogenous compounds into recalcitrant forms in laboratory conditions and occurrence of this chemical immobilization under field conditions would be consistent with field observations of reduced soil N supply. However, technological shortcomings have precluded its demonstration for naturally formed SOM. Through recent advances in nuclear magnetic resonance spectroscopy, agronomically significant quantities of lignin-bound N were found in a triple-cropped rice soil in the Philippines. A major research challenge is to demonstrate in the anaerobic agroecosystems that these lignin residues bind sufficient quantities of soil N to cause the observed yield decreases. A key objective will be to elucidate the cycling dynamics of lignin-bound N relative to the seasonal pattern of crop N demand. Anaerobic decomposition of crop residues may be the key feature of anaerobic cropping systems that promotes the accumulation of phenolic lignin residues and hence the covalent binding of soil N. Potential mitigation options include improved timing of applied N fertilizer, which has already been shown to reverse yield decreases in tropical rice, and aerobic decomposition of crop residues, which can be accomplished through field drainage or timing of tillage operations. Future research will evaluate whether aerobic decomposition promotes the formation of phenol-depleted SOM and greater in-season N mineralization, even when the soil is otherwise maintained under flooded conditions during the growing season.     

接种量对餐厨垃圾高温厌氧消化的影响

研究不同接种量对餐厨垃圾高温厌氧消化的影响,探求餐厨垃圾高温厌氧消化的最佳接种量。在55℃条件下,比较6种不同接种量对餐厨垃圾高温厌氧消化过程中pH、总磷浓度、VFA浓度、产气量及餐厨垃圾TS、VS去除效果和消化液COD_Cr去除效果的影响,结果表明：添加接种物不仅可以提高消化系统的缓冲能力,而且缩短系统产甲烷细菌的积累周期,有利于产气高峰提前,同时对餐厨垃圾的降解有一定的促进作用。其中,在消化物总量600 g条件下,480 g餐厨垃圾接种120 g接种物（TS比为9.47）产气效果最佳,整个过程累积产气量为9359 mL,显著高于其它处理,此外,餐厨垃圾TS、VS去除率和消化液COD_Cr去除率也达到最佳效果,去除率依次为60%、70%和39.67%,但是COD_Cr去除率与CK差异不显著。     

有机生活垃圾半干发酵菌群的分布变化特征

为了研究有机生活垃圾厌氧发酵中菌群的分布变化特征,以有机生活垃圾为生物质资源,进行半干式厌氧发酵试验。采用最大或然数法(most probable number,MPN)分析发酵过程中厌氧菌群时间和空间上的数量变化。结果表明:厌氧菌中产酸菌先于氨化菌达到最大值并占据优势地位,产甲烷菌在启动阶段初期基本没有增殖,第25天左右达到最大值3.2×109个/m L,随后产甲烷菌在整个盛产期数量维持在这一数量级上。厌氧纤维素降解菌菌数呈现缓慢增长的趋势,直到投料的第45天才增加到106个/m L。空间上厌氧产酸菌和甲烷菌的数量均是在基质条件稳定的中部位置和流动性较好的底部位置较多;厌氧氨化菌数量较多的为中部边缘和中部中心位置;厌氧纤维素降解菌主要在底部增殖。初步构建了产酸菌与产甲烷菌时间和空间的动力学模型,模型拟合效果良好,可为厌氧发酵工艺提供参考。该文对有机垃圾制取生物燃气的工艺过程具有理论指导意义。     

食品废物两相高温半干法厌氧发酵生产沼气初步研究

为了提高两相厌氧发酵工艺的生产性能,该文研究了一种新的两相半干法厌氧发酵沼气生产系统,即在水解相中批式发酵,每次从工作容积为4 L的产烷相中取500 mL接种液,与食品废物混合后发酵1～2 d,再全部输入产烷相继续生产沼气,如此循环.实验运行温度为50℃,食品废物总固体TS和挥发性固体VS分别为19.3%和16.1%,产烷相先在4gVS·d-1的进料率下单相运行至稳定,稳定期日产气量为(4.09±0.03)L(甲烷占69.0%),pH为7.50±0.02,TS和VS分别为(1.05±0.02)%和(0.64±0.02)%.稳定的产烷相与水解相联合后,水解相在60～700 g的进料量下都能正常产气,但氢气含量较低.产烷相在进料量600g时产气量最高,为29.1 L/d,随后受到抑制,受抑制前的甲烷含量为72.4%～74.0%,TS和VS含量也在该进料量后达到最高峰,分别为3.50%和2.32%.研究结果表明新的两相半干法厌氧发酵沼气生产系统有效提高了生产性能,在今后的研究中,需要降低从产烷相输入水解相的接种液量,以更好抑制水解相产烷微生物,提高产氢性能,还可使产烷相更加稳定,承受更高的进料量.     

Behavior of runoff-derived metals in a detention pond system

The removal and fate of runoff-derived heavy metals in a 1-yr old detention pond system were investigated during climatic conditions typical of the U.S. maritime Northwest. The catchment was a medium-sized, suburban parking lot near Portland, Oregon. Water samples from runoff, the detention pond system, and pond effluent were collected and analyzed for dissolved and particulate Cu. Copper was the dominant toxic metal for the study site, while analysis of selected samples for Pb and Cd showed these metals to be minor pollutants. Total Cu in runoff varied among different storm events over a wide range of concentrations (< 2 to 33 µg L^?1), while total Cu levels in pond effluent remained within a fairly narrow range (5 to 12 µg L^?1), Sediment samples collected from the detention pond system were analyzed for Cu in two size fractions (< 63 µm and < 125 µm). Copper was found to be deposited in the pond sediments in a small but highly concentrated plume (up to 130 mg kg^?1), extending axially from the runoff inlet pipe. Overall, results from this study showed that low-cost, small-scale detention ponds can be a useful management practice for runoff from parking lot areas and can be of value in preserving the integrity of receiving waters.     

生活有机垃圾厌氧发酵联产氢气和甲烷

以模拟的生活有机垃圾为原料,进行批式中温厌氧发酵联产氢气和甲烷。结果表明,与单独产氢相比,生活有机垃圾厌氧发酵联产氢气和甲烷能够显著提高能源回收效率。在产氢阶段,COD降解率为26.24%,且主要转化为中间代谢产物(如乙酸和丁酸),气体成分主要为氢气和二氧化碳,没有甲烷生成,氢气含量为31%～67%,挥发性固体(VC)氢气产率为55.4mL/g,能源回收率为3%(以热值计算)。在产甲烷阶段,中间代谢产物基本转化为甲烷,气体成分主要为甲烷和二氧化碳,没有氢气生成,甲烷含量稳定在68%～78%,VS产甲烷率为270.9mL/g,能源回收率为48.5%。整个厌氧发酵联产氢气和甲烷过程的COD去除率为60.65%,总能源回收效率为51.5%。     

蔬菜废弃物厌氧发酵制取沼气的试验研究

该文以废弃的甘蓝菜叶为发酵原料,在实验室自行设计的小型沼气发酵装置上进行了厌氧发酵试验,通过测定发酵过程中发酵液和沼气的各项指标,对蔬菜废弃物厌氧发酵的可行性及接种物浓度对发酵过程的影响进行了研究.结果表明,蔬菜废弃物用厌氧发酵工艺处理是可行的;在试验采用的20%,30%,50%三个水平的接种物浓度中,接种物浓度为30%的实验组的挥发酸含量、氨态氮含量以及pH值都在正常范围内,总产气量和沼气中最高甲烷含量分别为7790.81 mL和42.814%,明显高于其他两组及空白组实验.该项研究对蔬菜废弃物的资源化利用提供了有益的参考.