Virus and bacteria removal from wastewater by land treatment.

Secondary sewage effluent and renovated water from four wells at the Flushing Meadows Wastewater Renovation Project near Phoenix, Arizona, in operation since 1967, were assayed approximately every 2 months in 1974 for viruses and enteric bacteria during flooding periods. No viruses of Salmonella sp. were detected in any renovated well water samples, and the numbers of fecal coliforms, fecal streptococci, and total bacteria were decreased by about 99.9% in the renovated well waters after the wastewater was filtered through about 9 m of soil.     

Bacteriological evaluation of groups of beef carcasses before the wash at six Alberta abattoirs

K.W.F. JERICHO, J.A. BRADLEY AND G.C. KOZUB. 1994. A method has been developed for the bacteriological evaluation of groups of beef carcasses which can be used to measure the degree of control over hygiene during hide removal and carcass dressing in abattoirs. This method, which enumerates aerobic mesophilic bacteria automatically using a hydrophobic grid membrane filter, was applied at six abattoirs. Two hundred excision samples (5 × 5 × 0.5 cm) were taken at 10 sites on the external surface of a group of 20 carcasses (five carcasses were sampled on each of four consecutive daily visits) for group-carcass evaluation at each abattoir. For each abattoir, the mean log₁₀ Most Probable Number of Growth Units (MPNGU) and between-carcass variance component were obtained for each site and the average over sites. Using the average within-abattoir variance of this study and previously published studies involving 76 additional carcasses (Jericho et al. 1993), it was determined that 20 carcasses are more than adequate to estimate the mean log₁₀ MPNGU per cm² within 0.5 units at a site. The distribution of the log₁₀ MPNGU per cm² over the 10 sites was compared for the abattoirs, and sites were found to cluster into 2–4 homogenous groups. The means over sites of log₁₀ MPNGU per cm² for the abattoirs ranged from 1.52 to 2.64 and were unrelated to line speed     

污水土地处理生态工程综合效益评价——

为了科学、定量地评价污水土地处理生态工程的综合效益,运用层次分析法（AHP）,提出了评价指标体系、指标权重和综合效益计算方法.应用此方法对霍林河森林型慢速渗滤土地处理工程的综合效益进行了分析与评价.结果表明,霍林河森林型慢速渗滤土地处理工程的综合效益值CE=0.64,属于中级生态经济系统,而且具有良好的环境效益和社会效益.     

Treatment of distillery wastewater discharged from beet molasses-spirits production using yeast

Treatment of wastewater discharged from beet molasses-spirits production using yeast was studied. Two flocculant strains, Hansenula fabianii J 640-4-1 and Hansenula anomala J 45-N-5, and a strain, I-44, isolated from soil were suitable for treatment of wastewater at the concentration of 47,300 ppm of total organic carbon (TOC). Especially in the case of 2-step treatment using J 45-N-5 and I-44, TOC decreased to 11,900 ppm, and the C/N ratio (TOC/Total nitrogen) decreased from 14.8 to 4.6.     

Fate of virus in wastewater applied to slow-infiltration land treatment systems

The removal of seeded coliphage f2 and indigenous enteroviruses from primary and secondary wastewaters applied by spray irrigation to sandy loam and silt loam soils in field test cells was examined. The amount of f2 recovered from 170-cm-deep soil percolate samples taken over a 53-day period never exceeded 0.1% of applied virus levels and was usually below detection limits. Indigenous enterovirus levels in percolate waters also constituted only a small portion of those found in the wastewaters. At 10 days after seeding, f2 virus was present throughout the soil column but tended to accumulate around the soil core middepths. Coliphage f2 disappeared from the soil surface regions at a high rate, and by 53 days very little virus could be detected within the length of the soil columns. Sterilized soil core segments from different depths were studied to determine their virus adsorption capabilities when suspended in either wastewater, test cell percolate water, or distilled water containing divalent cations. The adsorptive capacity of Windsor and Charlton soils for poliovirus 1 and coliphage f2 increased greatly with the soil sample depth until leveling off at the midcore depths. Soil suspended in wastewater had the least virus adsorption capability for all depths studied.     

A review of influences of land use and land cover change on ecosystems

随着人口的增长和人类社会的发展, 土地利用与土地覆盖变化已经是不可避免。土地利用与土地覆盖变化不仅对生态系统的要素、结构和功能产生深远的影响, 也会对全球变化产生反馈作用。针对土地利用与土地覆盖变化的过程、驱动机制以及在各个方面可能产生的生态环境效应的科学研究已经全面开展。该文综述了土地利用与土地覆盖变化对气候、土壤、生物地球化学循环、生物多样性以及区域生态环境等影响方面的研究进展, 并提出了相关研究的前沿方向展望。随着新技术的不断发展, 学者们将更多地侧重预测未来全球变化背景下的土地利用与土地覆盖变化趋势、合理性以及适应性, 为可持续发展提供基础资料和理论依据。     

Minimizing land requirement and evaporation in small wastewater treatment systems

Water supplies in the Middle East arid climate are a scarce commodity making treated wastewater an economically attractive source for increasing the limited existing water resources for agricultural purposes. In order to minimize water losses with the corresponding increased salinity and to reduce land demand, an integrated system based mainly on high-rate semi-intensive treatment units is being tested and demonstrated. The units include an upflow anaerobic sludge blanket (UASB) reactor and vertical and horizontal flow wetlands. The units are characterized by simple and low-cost maintenance with minimal energy input. Three years of pilot plant results from the combined system are presented in this paper. The results show a high organic removal rate for the combined system: 140 g COD/m²/day for the scheme, which included a UASB reactor followed by two PAVB units and subsurface horizontal flow CW. Even higher rates of 900 g COD/m²/day were achieved for the same scheme by replacing the final CWL with another PAVB unit. These high rates allow for a small treatment plant footprint equivalent to 0.13–0.9 m² per person, assuming 125 g COD per person per day.     

土地利用与土地覆盖变化对生态系统的影响

随着人口的增长和人类社会的发展, 土地利用与土地覆盖变化已经是不可避免。土地利用与土地覆盖变化不仅对生态系统的要素、结构和功能产生深远的影响, 也会对全球变化产生反馈作用。针对土地利用与土地覆盖变化的过程、驱动机制以及在各个方面可能产生的生态环境效应的科学研究已经全面开展。该文综述了土地利用与土地覆盖变化对气候、土壤、生物地球化学循环、生物多样性以及区域生态环境等影响方面的研究进展, 并提出了相关研究的前沿方向展望。随着新技术的不断发展, 学者们将更多地侧重预测未来全球变化背景下的土地利用与土地覆盖变化趋势、合理性以及适应性, 为可持续发展提供基础资料和理论依据。     

A review of the sustainable value of effluents and sludges from wastewater stabilization ponds

Sludges and liquids from wastewater stabilization ponds are cost effective by-products useful for agriculture, aquaculture and for manufacturing building materials. They represent valuable sustainable resources as raw materials to support fisheries for human consumption, to produce animal feed derived from single cell algal proteins and aquatic weeds. Biogas from waste fermentation represents a significant tertiary product.Stabilization ponds are dynamic, low-cost waste recycling ecosystems comprising complex communities of algae, virus, protozoa, rotifers, insects, crustaceans and fungi. These organisms interact and modify the organic content of the waste to produce effluents which need little further investment in treatment.The economic, societal and sustainable value of stabilization ponds is governed by the management regime and the use for which the sludge and effluent is intended. Fish, ducks, prawn and algal protein production rely upon adequately treated effluent. This is particularly valuable for irrigation in arid and semi-arid climates, where natural waters are insufficient and nutrient depleted. Oxidation ponds provide sustainable mechanisms for dealing with sewage and for reducing the risk of infection from parasites and the effects of toxins. The resulting sludges can be used as fertilizer or be composted with local vegetation. Aerobic and anaerobic digestion, lime treatment and pasteurisation are used to improve sludge acceptability and utility to enhance its value as a sustainable resource.     

慢速渗滤土地处理系统对沈阳西部城市污水有机污染物净化效果的研究

本文研究了慢速渗滤土地处理系统对沈阳西部城市污水中有机污染物的净化效果和有机污染物在土地处理系统土壤中的残留情况。结果表明,在试验条件下,系统对有机污染物具有良好的净化效果,大多数有机污染物在系统输出水中未被检出,少数重点有机污染物在系统输出水中的浓度也明显降低,其中苯、氯苯、1,2-和1,4-二氯苯、苯酚,邻苯二甲酸二丁酯、γ-666等的含量已明显低于地面水水质标准建议值。系统对绝大多数重点有机污染物的去除率达95—100％,而不同重点有机污染物在土壤中的残留率为0—3％。     

Current research trends on microplastic pollution from wastewater systems: a critical review

Microplastics have been widely considered as contaminants for the environment and biota. Till now, most previous studies have focused on the identification and characterization of microplastics in freshwater, sea water, and the terrestrial environment. Although microplastics have been extensively detected in the wastewater, research in this area is still lacking and not thoroughly understood. To fill this knowledge gap, the current review article covers the analytical methods of microplastics originating from wastewater streams and describes their sources and occurrences in wastewater treatment plants (WWTPs). Studies indicated that microplastic pollution caused by domestic washing of synthetic fibers could be detected in the effluent; however, most microplastics from personal care and cosmetic products (PCCPs) can be efficiently removed during wastewater treatment. Moreover, various techniques for sampling and analyzing microplastics from wastewater systems are reviewed; while, the implementation of standardized protocols for microplastics is required. Finally, the fate of microplastics during wastewater treatments and the environmental contamination of effluent to environment are presented. Previous studies reported that the advanced wastewater treatment (e.g., membrane bioreactor) is needed for improving the removal efficiency of small-sized microplastics (<?100 µm). Although the role of microplastics as transport vectors for persistent organic pollutants (POPs) is still under debate, they have demonstrated abilities to absorb harmful agents like pharmaceuticals.

     

Filter materials for phosphorus removal from wastewater in treatment wetlands—A review

This paper aims to collect and analyse existing information on different filter media used for phosphorus (P) removal from wastewater in constructed wetlands. The most commonly used materials are categorized as natural materials (considered in 39 papers), industrial byproducts (25 papers) and man-made products (10 papers). A majority of studies on sorbents have been carried out in lab-scale systems as batch experiments, and only very few studies have highlighted results on full-scale systems. Among the great variety of filter media studied, most of materials had a pH level >7 and high Ca (CaO) content. The highest P-removal capacities were reported for various industrial byproducts (up to 420 g P kg⁻¹ for some furnace slags), followed by natural materials (maximum 40 g P kg⁻¹ for heated opoka) and man-made filter media (maximum 12 g P kg⁻¹ for Filtralite). We found a significant positive Spearman Rank Order Correlation between the P retention and CaO and Ca content of filter materials (R² = 0.51 and 0.43, respectively), whereas the relation of P retention to pH level was weak (R² = 0.22) but significant. There is probably an optimal level of hydraulic loading rate at which the P removal is the highest. Additional important factors determining the applicability of filter materials in treatment wetlands such as saturation time, availability at a local level, content of heavy metals, and the recyclability of saturated filter media as fertilizer should be taken into consideration.     

Survival of enteroviruses in rapid-infiltration basins during the land application of wastewater

The downward migration through soil of seeded poliovirus type 1 and echovirus type 1 and of naturally occurring enteroviruses during infiltration of sewage effluent through rapid-infiltration basins was investigated. After 5 days of flooding, the amount of seeded poliovirus type 1 that had migrated 5 to 10 cm downward through the soil profile was found to be 11% of that remaining at the initial burial depth. The amount of echovirus type 1 determined to have moved an equal distance was at least 100-fold less. Migration of naturally occurring enteroviruses during infiltration of sewage effluent through soil could not be measured with accuracy because of the possibility of virus survival from previous applications of effluent. The rate of inactivation for seeded poliovirus 1 and echovirus 1 buried in the infiltration basins ranged between 0.04 and 0.15 log10 units per day during the time when the basins were flooded. Inactivation of these same seeded virus types and of indigenous enterovirus populations in the infiltration basins during the drying portion of the sewage application cycle ranged between 0.11 and 0.52 log10 units per day. The rate of virus inactivation was dependent upon the rate of soil moisture loss. These results indicate that drying cycles during the land application of wastewater enhance virus inactivation in the soil.     

Fate of virus in wastewater applied to slow-infiltration land treatment systems.

The removal of seeded coliphage f2 and indigenous enteroviruses from primary and secondary wastewaters applied by spray irrigation to sandy loam and silt loam soils in field test cells was examined. The amount of f2 recovered from 170-cm-deep soil percolate samples taken over a 53-day period never exceeded 0.1% of applied virus levels and was usually below detection limits. Indigenous enterovirus levels in percolate waters also constituted only a small portion of those found in the wastewaters. At 10 days after seeding, f2 virus was present throughout the soil column but tended to accumulate around the soil core middepths. Coliphage f2 disappeared from the soil surface regions at a high rate, and by 53 days very little virus could be detected within the length of the soil columns. Sterilized soil core segments from different depths were studied to determine their virus adsorption capabilities when suspended in either wastewater, test cell percolate water, or distilled water containing divalent cations. The adsorptive capacity of Windsor and Charlton soils for poliovirus 1 and coliphage f2 increased greatly with the soil sample depth until leveling off at the midcore depths. Soil suspended in wastewater had the least virus adsorption capability for all depths studied.     

Effects of land irrigation with partially-treated wastewater on Frankia survival and infectivity

Phytoextraction of Cd by some populations of Thlaspi caerulescens which have the ability to co-hyperaccumulate Cd and Zn requires information about the distribution of both metals within the plant at the organ-level. This work was conducted to determine whether the distribution and solubility of Cd and Zn in Thlaspi caerulescens are affected by the age of plant and organ, and whether Cd and Zn have a common distribution in the plant in soils contaminated by both metals. A series of pot experiments were conducted where a Cd- and Zn-hyperaccumulating population was grown on soils contaminated by Cd and Zn. Temporal changes in metal concentration of roots and of shoots was recorded, along with the water and CaCl₂ solubility of metals in the plant organs. Also, leaves were grouped according to their age and their respective content of Cd and Zn was measured. Both metals were present at higher concentrations in leaves than in roots. The whole-plant content of Zn decreased with time while that of Cd increased or remained unchanged. At harvest, young leaves exhibited higher Cd concentration than older, but the reverse was true for Zn. Both metals were more soluble in dry leaves and senescent leaves than in fresh material, and Zn was more water-soluble than Cd. In conclusion, the distribution of Cd and Zn in the hyperaccumulator T. caerulescensvaried according to the organ and plant age, and Cd and Zn were shown to have a different distribution within the plant.     

土地系统动态模拟方法研究进展

土地系统动态模拟对土地利用规划、国土资源管理具有重要指导价值.基于经验统计的方法、多智能主体分析的方法、栅格邻域关系分析的方法以及近年来发展起来的土地系统动态模拟系统(DLS)方法是当前开展土地系统动态模拟的主要手段.本文综述了上述4种方法的原理、特点与应用案例,概括了相关方法在理论依据和推广应用等方面的优点与不足,展望了DLS在土地系统动态模拟方面的广阔应用前景.     

Diversity of culturable psychrophilic and psychrotrophic anaerobic bacteria isolated from beef abattoirs and their environments

This study identified 431 psychrophilic or psychrotrophic isolates from commercial Irish beef abattoir environments and "blown packs" of vacuum-packed beef, using PCR and 16S rRNA sequencing, and estimated their intraspecies genetic diversity using restriction fragment length polymorphism (RFLP) analysis and spacer region PCR (SR-PCR). Twenty-five species were identified in the 431 isolates, with the most frequently recovered species being Clostridium gasigenes (n=315), Clostridium estertheticum (n=17), and a potentially novel species designated strain TC1 (n=52). These species were previously found to be associated with a particular type of spoilage known as blown-pack spoilage (BPS), which occurs in chilled-stored (i.e., -1.5°C to 4°C) vacuum-packaged meat within 2 to 4 weeks and involves the production of large volumes of gas. Overall, the study demonstrates the considerable and not previously reported diversity of the anaerobic microflora in abattoirs and the presence of a wide range of organisms capable of causing BPS at chilled temperatures.     

Removal of pharmaceuticals and personal care products from wastewater using algae-based technologies: a review

Pharmaceuticals and personal care products (PPCPs) consist of a variety of compounds extensively used for the treatment of human and animal diseases and for health or cosmetic reasons. PPCPs are considered as emerging environmental contaminants due to their ubiquitous presence in the environment and high environmental risks. In wastewater treatment plants using conventional activated sludge processes, many PPCPs cannot be efficiently removed. Therefore, there is an increasing need for more effective and cost-efficiency ways of removing PPCPs while treating wastewater. Algae-based technologies have recently attracted growing attentions for their potential application in wastewater treatment and hazardous contaminant removal, which are advantages in reducing operation cost while generating valuable products and sequestrating greenhouse gases at the same time. This work reviews the up-to date researches to reveal potential toxic effects of PPCPs on algae and algae-bacteria consortia, identify mechanisms involved in PPCP removal, and assess the fate of PPCPs in algae-based treatment systems. Current researches suggest that algae and algae-bacteria consortia have great potentials in PPCP removal but more works are required before algae-based technologies can be implemented in large scales. Knowledge gaps are identified and further research focuses are proposed in this review.     

Treatment of cyanide-containing wastewater from the food industry in a laboratory-scale fixed-bed methanogenic reactor

During the process of producing cassava starch from Manihot esculenta roots, large amounts of cyanoglycosides were released, which rapidly decayed to CN⁻ following enzymatic hydrolysis. Depending on the varying cyanoglycoside content of the cassava varieties, the cyanide concentration in the wastewater was as high as 200 mg/l. To simulate anaerobic stabilization, a wastewater with a chemical oxygen demand (COD) of about 20 g/l was prepared from cassava roots and was fermented in a fixed-bed methanogenic reactor. The start-up phase for a 99% degradation of low concentrations of cyanide (10 mg/l) required about 6 months. After establishment of the biofilm, a cyanide concentration of up to 150 mg CN⁻/l in the fresh wastewater was degraded during anaerobic treatment at a hydraulic retention time of 3 days. All nitrogen from the degraded cyanide was converted to organic nitrogen by the biomass of the effluent. The cyanide-degrading biocoenosis of the anaerobic reactor could tolerate shock concentrations of cyanide up to 240 mg CN⁻/l for a short time. Up to 5 mmol/l NH₄Cl (i.e. 70 mg N/l = 265 mg NH₄Cl/l) in the fresh wastewater did not affect cyanide degradation. The bleaching agent sulphite, however, had a negative effect on COD and cyanide removal. For anaerobic treatment, the maximum COD space loading was 12 g l⁻¹ day⁻¹, equivalent to a hydraulic retention time of 1.8 days. The COD removal efficiency was around 90%. The maximum permanent cyanide space loading was 50 mg CN⁻ l⁻¹ day⁻¹, with tolerable shock loadings up to 75 mg CN⁻ l⁻¹day⁻¹. Under steady-state conditions, the cyanide concentration of the effluent was lower than 0.5 mg/l. Received: 15 August 1997 / Received revision: 10 October 1997 / Accepted: 14 October 1997     

人工湿地对猪场废水有机物处理效果的研究

分别以香根草 (Vetiveriazizanioides)和风车草 (Cyperusalternifolius)为植被 ,按 1.0m× 0 .5m×0 .8m建立人工湿地 ,通过 4季测试 ,研究其对猪场废水有机物的净化功能及其随季节、进水浓度及水力停留时间变化的规律 .结果表明 ,4个季节香根草或风车草人工湿地对COD和BOD有较稳定的去除效果 ,两湿地抗有机负荷冲击能力强 .在春季 ,停留时间 1～ 2d ,COD和BOD去除率分别为 70 %和 80 %;在夏季 ,进水COD高达 10 0 0～ 140 0mg·L-1情况下 ,COD去除率接近 90 %;在秋季 ,停留时间 1～ 2d ,COD和BOD去除率分别为 5 0 %～ 6 0 %和 5 0 %;在冬季 ,进水COD达 10 0 3mg·L-1情况下 ,COD去除率在 70 %以上 .COD、BOD和SS的去除率在两湿地间没有显著差异 .人工湿地污染物 (Y)随水力停留时间 (t)延长的降解遵从指数方程规律Yt=Y0 ·e( -kt) .在相同停留时间时 ,随进水污染物浓度 (x)提高的出水污染物浓度 (y)的回归关系遵从直线方程规律 y =a+bx .