Procedure for the recovery of airborne human enteric viruses during spray irrigation of treated wastewater.

Because of the relatively low number of indigenous enteric viruses recovered from secondary wastewater effluents, their presence in air (aerosols) as a result of wastewater spray irrigation requires extensive sampling. Methodology to allow the recovery of indigenous enteroviruses from aerosols generated at an operational wastewater irrigation site was tested under both laboratory and field conditions.     

Source Bioaerosol Concentration and rRNA Gene-Based Identification of Microorganisms Aerosolized at a Flood Irrigation Wastewater Reuse Site

Reuse of partially treated domestic wastewater for agricultural irrigation is a growing practice in arid regions throughout the world. A field sampling campaign to determine bioaerosol concentration, culturability, and identity at various wind speeds was conducted at a flooded wastewater irrigation site in Mexicali, Baja California, Mexico. Direct fluorescent microscopy measurements for total microorganisms, culture-based assays for heterotrophs and gram-negative enteric bacteria, and small-subunit rRNA gene-based cloning were used for microbial characterizations of aerosols and effluent wastewater samples. Bioaerosol results were divided into two wind speed regimens: (i) below 1.9 m/s, average speed 0.5 m/s, and (ii) above 1.9 m/s, average speed 4.5 m/s. Average air-borne concentration of total microorganisms, culturable heterotrophs, and gram-negative enteric bacteria were, respectively, 1.1, 4.2, and 6.2 orders of magnitude greater during the high-wind-speed regimen. Small-subunit rRNA gene clone libraries processed from samples from air and the irrigation effluent wastewater during a high-wind sampling event indicate that the majority of air clone sequences were more than 98% similar to clone sequences retrieved from the effluent wastewater sample. Overall results indicate that wind is a potential aerosolization mechanism of viable wastewater microorganisms at flood irrigation sites.     

Source bioaerosol concentration and rRNA gene-based identification of microorganisms aerosolized at a flood irrigation wastewater reuse site

Reuse of partially treated domestic wastewater for agricultural irrigation is a growing practice in arid regions throughout the world. A field sampling campaign to determine bioaerosol concentration, culturability, and identity at various wind speeds was conducted at a flooded wastewater irrigation site in Mexicali, Baja California, Mexico. Direct fluorescent microscopy measurements for total microorganisms, culture-based assays for heterotrophs and gram-negative enteric bacteria, and small-subunit rRNA gene-based cloning were used for microbial characterizations of aerosols and effluent wastewater samples. Bioaerosol results were divided into two wind speed regimens: (i) below 1.9 m/s, average speed 0.5 m/s, and (ii) above 1.9 m/s, average speed 4.5 m/s. Average air-borne concentration of total microorganisms, culturable heterotrophs, and gram-negative enteric bacteria were, respectively, 1.1, 4.2, and 6.2 orders of magnitude greater during the high-wind-speed regimen. Small-subunit rRNA gene clone libraries processed from samples from air and the irrigation effluent wastewater during a high-wind sampling event indicate that the majority of air clone sequences were more than 98% similar to clone sequences retrieved from the effluent wastewater sample. Overall results indicate that wind is a potential aerosolization mechanism of viable wastewater microorganisms at flood irrigation sites.     

Comparison of coliphage and bacterial aerosols at a wastewater spray irrigation site.

Microbiological aerosols were measured on a spray irrigation site at Fort Huachuca, Ariz. Indigenous bacteria and tracer bacteriophage were sampled from sprays of chlorinated and unchlorinated secondary-treatment wastewaters during day and night periods. Aerosol dispersal and downwind migration were determined. Bacterial and coliphage f2 aerosols were sampled by using Andersen viable type stacked-sieve and high-volume electrostatic precipitator samplers. Bacterial standard plate counts averaged 2.4 x 10(5) colony-forming units per ml in unchlorinated effluents. Bacterial aerosols reached 500 bacteria per m3 at 152 m downwind and 10,500 bacteria per m3 at 46m. Seeded coliphage f2 averaged 4.0 x 10(5) plaque-forming units per ml in the effluent and were detected 563 m downwind. Downwind microbial aerosol levels were somewhat enhanced by nighttime conditions. The median aerodynamic particle size of the microbial aerosols was approximately 5.0 micrometer. Chlorination reduced wastewater bacterial levels 99.97% and reduced aerosol concentrations to near background levels; coliphage f2 was reduced only 95.4% in the chlorinated effluent and was readily measured 137 m downwind. Microbiological source strength an meteorological data were used in conjunction with a dispersion model to generate mathematical predictions of aerosol strength at various sampler locations. The mean calculated survival of aerosolized bacteria (standard plate count) in the range 46 to 76 m downwind was 5.2%, and that of coliphage f2 was 4.3 %.     

Spatial distribution of total halogenated organic compounds (TX), adsorbable organic halogens (AOX), and heavy metals in wetland soil irrigated with pulp and paper wastewater

Long-term irrigation using wastewater from paper industry may cause seriously problems to the receiving soil. This work surveyed and monitored the soil quality of a wastewater irrigation wetland system in Yancheng City, Jiangsu Province in China in 2014 and 2015. Τhe wetland soil showed different soil properties and TX, AOX, heavy metal contents after long-term wastewater irrigation. Long-term irrigation also accumulated the heavy metals such as Cu, Cd, Zn, and Pb in the wetland soil. Compared to the control, TX in the irrigated soil increased by 47.7–69.8% (2014) and 61.5–83.1% (2015). AOX varied in concentration from 1.7 to 55.0 mg kg^?1 (2014) and 11.0 to 53.0 mg kg^?1 (2015). The long-term irrigation of wastewater to wetland systems caused the accumulations of heavy metals, TX, and AOX in the soil and the levels of accumulations were related to several factors including soil properties, wastewater quality, and irrigation time.     

养殖污水直灌对稻田土壤氮、磷积累与垂直迁移的影响

尽管国内外对养殖污水处理已提出了一系列的工艺技术,但因经济原因养殖污水直接灌溉农田在我国农村地区仍较为常见.为了解长期畜禽养殖污水直灌对稻田土壤质量的影响,在浙江省绍兴市柯桥区选择了养殖污水直灌不同年限(0、4、7、13年)的稻田,比较研究了养殖污水直接灌溉对稻田土壤不同深度土层中各形态氮和磷含量的影响,探讨了长期养殖污水灌溉对氮、磷在土壤剖面中垂直迁移的影响.结果表明: 长期养殖污水直接灌溉可显著提高稻田土壤中氮和磷的积累,积累量随灌溉年限的增长而增加,其中磷素的增幅高于氮素.养殖污水灌溉4、7和13年后,土壤表层中全P和全N分别比对照增加了43.6%、95.2%、1484%和7.7%、17.0%、28.4%.土壤氮素的变化为NH₄⁺-N、NO₃^--N>酸解有机氮>非酸解有机氮;土壤有效磷的变化明显大于全磷.长期养殖污水灌溉可促进氮、磷在土壤剖面中的垂直迁移,增加对地下水的污染风险.
     

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.     

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.     

Microbial contamination of vegetable crop and soil profile in arid regions under controlled application of domestic wastewater

Increasing lack of potable water in arid countries leads to the use of treated wastewater for crop production. However, the use of inappropriate irrigation practices could result in a serious contamination risk to plants, soils, and groundwater with sewage water. This research was initiated in view to the increasing danger of vegetable crops and groundwater contamination with pathogenic bacteria due to wastewater land application. The research was designed to study: (1) the effect of treated wastewater irrigation on the yield and microbial contamination of the radish plant under field conditions; (2) contamination of the agricultural soil profile with fecal coliform bacteria. Effluent from a domestic wastewater treatment plant (100%) in Jeddah city, Saudi Arabia, was diluted to 80% and 40% with the groundwater of the experimental site constituting three different water qualities plus groundwater as control. Radish plant was grown in two consecutive seasons under two drip irrigation systems and four irrigation water qualities. Upon harvesting, plant weight per ha, total bacterial, fecal coliform, fecal streptococci were detected per 100 g of dry matter and compared with the control. The soil profile was also sampled at an equal distance of 3 cm from soil surface for fecal coliform detection. The results indicated that the yield increased significantly under the subsurface irrigation system and the control water quality compared to surface irrigation system and other water qualities. There was a considerable drop in the count of all bacteria species under the subsurface irrigation system compared to surface irrigation. The bacterial count/g of the plant shoot system increased as the percentage of wastewater in the irrigation water increased. Most of the fecal coliform bacteria were deposited in the first few centimeters below the column inlet and the profile exponentially decreased with increasing depth.     

矿井废水灌溉对小麦生理特性及重金属积累的影响

以井水灌溉为对照 (CK),采用盆栽试验研究了矿井废水灌溉对小麦生理特性和重金属积累的影响.设置了3个矿区废水灌溉处理:洗煤废水(T₁)、经沉淀处理的洗煤废水 (T₂) 和煤矸石淋溶水 (T₃),于返青期开始进行矿区废水灌溉处理.结果表明： 矿井废水灌溉处理对小麦的生长发育和产量均有不同程度的负面影响.到开花期时,T₁、T₂和T₃处理小麦的单茎质量和叶面积、根系活力和光合速率均显著低于对照(P＜0.05),T₃处理小麦株高和叶绿素含量(SPAD值)显著降低(P＜0.05);T₁、T₂和T₃处理的籽粒产量分别比对照下降15.4%、9.8%和17.8%.此外,矿井废水灌溉处理小麦籽粒中Cr、Pb、Cu和Zn的含量均显著高于对照,表明矿井废水灌溉导致重金属在小麦籽粒中积累.
     

Ecology of cycloheximide-resistant fungi in field soils receiving raw city wastewater or normal irrigation water

The effect of raw city wastewater irrigation on biodiversity and population densities of a cycloheximide-resistant (CH) fungal community was studied in 13 field soils receiving either raw city wastewater or normal irrigation, and in raw city wastewater in the Nablus area, using the hair baiting technique (HBT) and a surface soil dilution plating (SSDP) technique. Three of these fields [one had been receiving raw city wastewater for more than ten years and was designated a heavily polluted field, and the other 2 were cultivated for the first time and were either irrigated with raw city wastewater (newly polluted field) or normal irrigation water (nonpolluted)], were sampled 4–7 times over a 9-month period. The other ten fields, which had been under raw city wastewater irrigation for more than 10 years, were sampled only once. Fifty-seven CH-resistant species belonging to 18 genera were recovered, of which 49 species were recovered from soil habitats and 28 species from raw city wastewater. The HBT had shown to be more efficient in the isolation of pathogenic and potentially pathogenic fungi including dermatophytes. A higher percentage of this group of fungi was recovered from the three main field soils studied using HBT (70% of all isolates), than the SSDP (35.5%); no dermatophytes were recovered by the SSDP method. Two dermatophytes (Microsporum gypseum, and Trichophyton ajelloi), and five more fungi (Arthroderma cuniculi, A. curreyi, Chrysosporium keratinophilum, C. tropicum, and C. pannorum), were recovered from these habitats. Wastewater irrigation seemed to have affected the fungal population densities, with the highest population densities being found in the heavily polluted field soil, while lower population densities were found in the nonpolluted field soil. Increases in organic matter were also observed as a result of sewage effluent irrigation. However, basic similarities in the biodiversity of CH-resistant fungal communities existed in nonpolluted and polluted field soils, and raw city wastewater. Comparable numbers of fungal species were recovered from the three main field soils. The species most commonly found in those habitats included: Alternaria alternata, Aspergillus candidus, Geotrichum candidum, and Paecilomyces lilacinus. Field soils receiving either raw city wastewater or normal irrigation water, were found to be rich in pathogenic and potentially pathogenic CH-resistant fungi, including dermatophytes, with raw city wastewater yielding the highest percentage (81%), followed by the newly wastewater irrigated field (77.7%), the nonpolluted field (67%), and the heavily polluted field (63.4%). Hygienic measures should therefore be taken to control the spread of these fungi in the environment of human communities, and to avoid mycotic infections among farmers. This revised version was published online in August 2006 with corrections to the Cover Date.     

Vesicular-arbuscular mycorrhizae in a wastewater-irrigated oldfield ecosystem in Michigan

The incidence of vesicular-arbuscular mycorrhizae (VAM) in wastewater irrigated and non-irrigated oldfield soils in Michigan was studied. Soil and root samples were taken monthly from field plots on the second and third years of consecutive irrigation with municipal wastewater at rates of 0, 5 and 10 cm wk^–1. The oldfield ecosystem contained a high VAM fungal spore population density, but low species diversity. The most common VAM fungal species were Glomus mosseae and G. fasciculatum. Both spore density and root colonization were higher in irrigated than in non-irrigated plots. Irrigation effects were largest early in the growing season. In addition to increasing VAM incidence, wastewater irrigation shifted VAM fungal species composition. Irrigation favored G. mosseae over G. fasciculatum. Bioassays using either Sorghum vulgare or Daucus carota, an oldfield native species, indicated that the VAM systems were still functioning after the third year of consecutive wastewater irrigation. The data from experiments using nutrient solutions at wastewater concentrations suggest that the effects of wastewater irrigation on VAM are due to the effects of both water and nutrients. Since VAM are a very important component of the plant's water and nutrient uptake system and equally important in structuring plant communities under limiting growth conditions, it is suggested that the stimulatory effect of wastewater irrigation on VAM in an oldfield ecosystem enhances the ecosystem's ability to function as a living filter for wastewater clean up.Michigan Agricultural Experimental Station Journal Article No 13137.On sabbatical leave from ESAL, Lavras-MG, Brazil     

慢速渗滤土地处理系统中优先有机物的迁移、归宿与生态风险

研究了沈阳西部城市污水慢速渗滤土地处理系统中优先有机污染物的迁移和残留情况,结果表明,土地处理系统和当地传统污灌区耕作层土壤、地下水中的优先有机污染物的总含量分别高于对照区（清水灌区）１倍和４倍以上;系统出水、地下水和传统污灌区地下水中的优先有机污染物的浓度有相似的分布、说明污灌水中的有机污染物对土壤和地下水产生一定程度的影响,但土地处理系统和当地传统污灌区生产的大米中,优先有机污染物含量与对照区相比未见显著差异．     

再生(污)水灌溉生态风险与可持续利用

作为一个农业大国,水资源贫乏及地域分布不均匀造成了我国严重的农业用水危机。为缓解我国农业用水危机,污水灌溉及再生水灌溉已成为解决农业灌溉水源不足的一项重要措施。在总结污水灌溉及再生水灌溉生态风险的基础上,针对国内研究现状,分析了我国再生水灌溉利用的可行性。研究发现,再生水灌溉的污染风险远小于污水灌溉,且再生水灌溉还具有回用成本低、减少农作物生产成本等经济效益,以及减少污染物向水环境中排放、改善土壤质量等环境效益。与污水灌溉相比再生水在农业灌溉上具有较大的应用前景,应加大其推广与应用的力度。最后,根据国内外的研究现状,提出了一些再生水灌溉可持续管理措施及其安全利用的相关建议。     

The tradition of groundwater irrigation in Northwestern India

Ethnographic research in the central Aravalli Hills of Rajasthan documents a coherent system of groundwater irrigation distinctively different from the system of dams, wiers, and perennial canals redesigned for India by the British during the early nineteenth century and continued by contemporary Indian governments. This paper articulates these indigenous principles and practices and contrasts them with those found in the scholarly literature on irrigation in Rajasthan which follows modern engineering concerns. Our analysis indicates a difference set of questions to guide future research on surface impoundments and groundwater management. Furthermore, this study has broader implications for an understanding of the human-shaped hydrology of northwestern India, where the earlier system has been overlaid, but not fully displaced by subsequent irrigation projects. Indeed, indigenous practices involving groundwater recharge and retrieval may have continued to flourish and expand, achieving a new order of hydrologic and adaptive complexity, through the local initiative of the peasantry to adapt to the unintended spillage, soakage, and siltage from the grand system of dams and perennial canals constructed by the state.     

Wastewater reuse in agriculture and the risk of intestinal nematode infection

The increasing use of wastewater for crop irrigation in arid and semi-arid zones means that wastewater parasitology is becoming on important research area. The World Health Organization's (WHO) current guideline states that only treated wastewater containing no more than one human intestinal nematode egg per litre should be used for irrigation. This guideline was based on very limited epidemiological evidence. In this article Rachel Ayres, Rebecca Stott, Duncan Mara and Donald Lee describe their recent work in Yorkshire and northeast Brazil and suggest that their results may be the first evidence for relaxing the WHO guideline for restricted irrigation to no more than ten intestinal nematode eggs per litre.     

Responses of pea and wheat to textile wastewater reclaimed by suspended sequencing batch bioreactors

Availability of good quality water for crop irrigation is a big challenge in developing countries due to limited resources of clean water. Textile industry consumes a huge amount of water during dyeing process and consequently it releases high strength wastewater into wastewater streams. The present study was designed with the objective to use textile wastewater treated in sequencing batch bioreactor for irrigation purpose. Wastewater containing 100 mg/L reactive black-5 azo dye amended with different co-substrates was treated using mixed liquor suspended solids (MLSS) and two previously isolated dye-degrading bacterial strains (Psychrobacter alimentarius KS23 and Staphylococcus equorum KS26). About 90% color and COD removal in case of dye-containing wastewater amended either with mineral salts + yeast extract or only yeast extract was achieved in 24 h after treatment with mixed culture (MLSS + KS23 + KS26). The treated wastewater was applied for irrigation of pea and wheat plants under controlled conditions. Untreated dye-contaminated wastewater was used as a control for comparison. A significant positive effect of treated dye wastewater amended with different co-substrates on the seed germination index, root and shoot length and biomass was observed in response to application of dye-containing wastewater treated with MLSS and dye-degrading bacterial strains compared to untreated control. Results of this study reveal that the dye-degrading microbial cultures could be used to enhance the treatment efficiency of dye-contaminated wastewater that can be utilized for irrigation of crops and biomass production.     

再生水灌溉对黄瓜和西红柿养分元素分布特征及果实品质的影响

通过田间试验,研究再生水不同灌溉处理对黄瓜、西红柿植株各部位养分元素的分布特征及果实品质的影响.结果表明:再生水灌溉对西红柿的生长发育有促进作用,对黄瓜的生长发育有一定的抑制作用.再生水灌溉后,氮具有向植株地上部分运输的特征;钾易于在黄瓜叶片中富集,不易于在西红柿根部富集;钠主要富集在根系中,叶片中的浓度较低,不会对作物造成伤害;对各部位Ca2+、Mg2+、Cl-的分配没有显著影响.再生水灌溉对黄瓜、西红柿品质无显著影响,果实中硝态氮浓度分别增加了5.3%和32.9%,但均低于国家标准限值.     

Assessment of Heavy Metals in Pharmacological Important Medicinal Plants Consumed in the Bannu District,Pakistan

This study assesses the contents of heavy metals in the four most commonly used indigenous medicinal plants in the Bannu District, Pakistan. The rapid appraisal approach was used along with semi-structured interviews with elderly people and herbalists for selection of indigenous plants. Heavy metals were determined via flame atomic absorption spectrometer by acid digestion of samples. Four medicinal plants were selected after interviews of 53 local residents and herbalists. Plant and soil samples were obtained for evaluations from a wastewater zone (WWZ) and a clean water zone (CWZ). Indigenous plants from the WWZ showed considerably higher metal contents compared to the CWZ. The trend of metals for indigenous medicinal plants grown in clean water was Mn > K > Na > Zn > Co > Fe > Cu while for wastewater the trend appeared as Co > K > Na > Zn > Fe > Mn > Cu. An alternative significant extent of research is needed to qualify the assessment of the human health insinuations of consumption of indigenous remedies. The heavy metal content of administering herbal medicine should be screened, as formulation and processing of medicine may affect heavy metal contents of the remedies.     

Characteristics,and carbon and nitrogen dynamics in soil irrigated with wastewater for different lengths of time

Irrigation of agricultural land with wastewater will increase crop production, but also heavy metal concentrations and the rate of infection of farmers with pathogens. The risks associated with the use of wastewater are reduced by treating the wastewater, but treatment also reduces organic material, phosphorus and inorganic N for crops. We investigated characteristics, e.g. heavy metal concentrations, of soils of the valley of the Mezquital (Mexico) irrigated with waste from Mexico City water since 1912, 1925, 1965, 1976, 1996 or 1997, or not irrigated at all, and dynamics of C and N when soil was amended with wastewater or drainage water. Concentrations of total Mg, Hg, Mo, Ca, Cu and Cr, available concentrations of Pb, Cd and Cu increased significantly with length of irrigation (P < 0.05), but were not at hazardous concentrations. Although organic C, total N, microbial biomass C and N, and microbial activity, as witnessed by CO2 production, increased with length of irrigation, N mineralization did not. Oxidation of NO2- was inhibited and could be due to increases in salinity, toxic compounds or heavy metals. We found that N mineralization was low or absent so it will not compensate for the loss of N when the wastewater is treated and application of N fertilizer will be required to maintain the same level of crop production. The characteristics of the soils appear not to have deteriorated after years of application of wastewater, but further irrigation even with treated wastewater might increase sodicity and salinity and pose a threat to future crop production.