Evaluating greywater reuse potential for sustainable water resources management in Oman

This study aims to evaluate the potential of greywater availability in Muscat Governorate in the Sultanate of Oman, to establish a methodology for greywater quantity estimation, to test greywater quality in order to assess reuse potential, and to examine public acceptance for reuse.Total fresh water consumption and greywater generation from different household sources were measured by water meters in five selected households during summer and winter. Additionally, a survey was designed and conducted in five administrative areas of Muscat Governorate, with the objective of testing a methodology for estimating greywater generation potential in these areas. Collected data were compared with that used by the Ministry of Housing, Electricity and Water, Sultanate of Oman. The survey covered a total of 169 houses and 1,365 people. Greywater samples were collected and analyzed from showers, laundries, kitchens and sinks in some of these households to determine their water quality parameters. Statistical analysis results indicated that there is no significant variance in the total fresh water consumption between data used by the ministry and those measured and estimated during this study, highlighting the applicability of the tested method. The study concluded that the average per capita greywater generation rate is 151 Lpcd. Greywater production ranged from 80 to 83% of the total fresh water consumption and most of the greywater is generated from showers. Further, 55 to 57% of the greywater generated in a typical Omani household originated from the shower, 28 to 33% originated from the kitchen, 6 to 9% originated from laundry, and 5 to 7% originated from sink, which constitutes approximately 81% of the total fresh water consumption. The physical, chemical, and biological analyses of the grab samples revealed that greywater contains significant levels of suspended solids, inorganic constituents, total organic carbon, chemical and biochemical oxygen demands, total Coliforms and Escherichia Coliform bacteria. The public acceptance survey illustrated that approximately 76% of the respondents accepted the reuse of greywater for gardening, 53% for car washing and 66% for toilet flushing.     

Characterisation of Indicator Organisms and Pathogens in Domestic Greywater for Recycling

Greywater from baths, showers and washbasins was collected separately from all other domestic wastewater at a university block of flats with a dual reticulation system and analysed for a range of contaminants including indicator organisms and pathogens. Greywater flow and temperature were also monitored and a diurnal variation was observed. Physical and chemical water quality parameters were similar to previously published data, although measured COD and BOD levels appeared to be lower, possibly due to settlement or biodegradation in the storage tanks. Plate counts and indicator organism concentrations were consistently high suggesting a high level of human bacterial contamination necessitating biological treatment and disinfection if the water is to be used for recycling. However, these high levels of indicator organisms did not correlate to pathogen presence and should not be used as pathogen indicators in greywater. One positive count of Salmonella veltereden was observed as well as low levels of Giardia. Cryptosporidium, Escherichia coli O157:H7, enteroviruses and Legionella were not identified in any of the samples. The research also highlighted a number of problems with the complexity of this type of sampling programme, such as identifying the most likely time to isolate pathogens and analysing an ‘unusual’ water source.     

Chemical, biochemical, and biological impact of untreated domestic sewage water use on Vertisol and its consequences on wheat (Triticum aestivum) productivity

In the peri-urban areas of central India, sewage water is a valuable resource for agricultural production. In this study, impact of domestic sewage water irrigation for 5 years on Vertisol with no previous history of sewage irrigation was investigated in an ongoing field experiment at Bhopal (India) under subtropical monsoon type climate. The wheat (Triticum aestivum) crop was grown during post-rainy winter season with 30 cm of irrigation (groundwater or sewage water) and four nutrient treatments (T₁, 0; T₂, 100%; T₃, 50%; and T₄, 50% of general recommended doses of NPK + FYM at 10 Mg/ha). Results showed that sewage irrigation of about 150 cm over a period of 5 years resulted significant increases in salinity as well as available fractions of N, P, K, and micronutrients, viz., Zn, Fe, and Mn in soils. Carbon and phosphorus applied through sewage water were accumulated more in subsoil layer compared to topmost plough layer. Soil microbiological activity, as indicated by soil respiration, microbial biomass C, as well as dehydrogenase enzyme activity was higher in sewage water-irrigated soils. There was also significant increase in fungal and actinomycetes as well as total coliform population in such soils. Nutrients supplied through sewage water were not able to raise the productivity of wheat to the level that obtained through fertilizers at the recommended level which indicated that additional nutrients through fertilizers are required to obtain higher productivity of wheat under sewage farming. Protein and Zn content in wheat grains were more when the crop was grown with sewage irrigation. Overall results show that except for increase in coliform population, short duration (5 years) of municipal sewage water irrigation did not have any appreciable harmful effect on soil quality as well as crop productivity; rather, it proved beneficial in improving soil fertility, wheat productivity, and produce quality.     

Evaluating soil quality under a long-term integrated tillage–water–nutrient experiment with intensive rice–wheat rotation in a semi-arid Inceptisol,India

Long-term sustainability and a declining trend in productivity of rice–wheat rotation in the Indo-Gangetic plain, often direct towards the changes in soil quality parameters. Soil quality is decided through few sensitive soil physical, chemical and biological indicators as it cannot be measured directly. The present investigation was carried out to develop a valid soil quality index through some chosen indicators under long-term influences of tillage, water and nutrient-management practices in a rice–wheat cropping system. The experiment consisted of two tillage treatments, three irrigation treatments, and nine nutrient management treatments for both rice and wheat, was continued for 8 years. The index was developed using expert-opinion based conceptual framework model. After harvest of rice, the CFSQI-P (productivity) was higher under puddled situation, whereas CFSQI-EP (environmental protection) was more under non-puddled condition and 3-days of drainage was found promising for all the indices. No-tillage practice always showed higher soil quality index. The treatments either receiving full organics (100 % N) or 25 % substitution of fertilizer N with organics showed higher soil quality indices. Puddling, irrigation after 3 days of drainage and substitution of 25 % recommended fertilizer N dose with FYM in rice could be practiced for maintaining or enhancing soil quality. No-tillage, two irrigations, and domestic sewage sludge in wheat can safely be recommended for achieving higher soil quality.     

Assessment of deterioration in water quality from source to household storage in semi-urban settings of developing countries

This study has investigated the common risks associated with the water quality changes from the source to the consumer households and the associated disease burden in the piped water supplies. Samples from the source to the household storage from Nagpur City were collected and analysed for heavy metals, nutrient and microbial parameters. Sanitary risks were identified at the households during the socio-economic and sanitary survey. The water quality deterioration was the most at household storage around 30.3 % indicating that measures need to be taken to safeguard the water quality at the consumer level. Then, 31.2 % of the samples collected from public standposts and handpumps were positive for faecal contamination which implies that it is the weaker sections of the society who suffer the consequences of drinking unsafe water the most. On the basis of the laboratory results, risk analysis by surveying the WTPs, point-of-use behaviour at households and sanitary status at different socio-economic strata, the Water Safety Plan for Nagpur City was structured. The aim was to ensure that safe and improved water is reached to the individual household.     

Impact of sewage contaminated water on soil, vegetables, and underground water of peri-urban Peshawar, Pakistan

The use of sewage-contaminated municipal water for irrigation of crops is an old practice in many big cities of Pakistan. Since the wastewater is rich in nutrients, it increases crops yield substantially but at the cost of food quality. The objective of this study was to investigate sewage water irrigation as a source of accumulation of heavy metals in soil and its subsequent transfer to crops and underground water. Sewage water, soil, groundwater, and crop samples were collected from selected areas around Peshawar city and analyzed for heavy metals concentration by atomic absorption spectroscopic method. Analysis of data revealed a considerable impact of the irrigation practices in the peri-urban Peshawar. Statistical analysis of the data showed a positive correlation between heavy metals concentration and soil carbon contents on the one hand and cation exchange capacity on the other. A strongly negative correlation was observed between metal contents and soil pH. The vertical movement of heavy metals from contaminated soil has polluted crops and underground water. The results indicated higher concentration of toxic metals in soil accumulated due to long-term sewage-contaminated water irrigation and their subsequent transfer to our food chain. The practice, if continued un-noticed may pose a threat of phytotoxicity to the local population.     

Quality of wastewater reuse in agricultural irrigation and its impact on public health

This study is planned to perform a sanitary survey of the largest sewage treatment plant in Riyadh, KSA, fortnightly for 6 months to examine its effluent quality as an example for the growing dependence on reuse of treated municipal wastewater in agricultural irrigation purposes to cope with increasing water shortage. The biological and physico-chemical parameters of 12 wastewater samples from the plant were examined using standard methods. The physico-chemical analysis indicated that the surveyed municipal wastewater treatment plant contained some of the studied parameters, such as turbidity, total suspended solids, biochemical oxygen demand, chemical oxygen demand and residual chlorine above the maximum permissible wastewater limits set by the Saudi Standards. However, heavy metal concentrations in all samples were lower than the recommended standards. Total and faecal coliform counts were above the permissible limits indicating poor sanitation level. Fifty percent of all wastewater samples were contaminated with faecal coliforms but, surprisingly, Escherichia coli were only detected in 8.3 % of the samples. Regular monitoring and enhancement of microbial and physico-chemical parameters of the wastewater quality served by different wastewater treatment plants for reuse in agricultural irrigation is recommended to preserve the environment and public health.     

Accounting for intracultural variability in first nation environmental knowledge: A requisite for environmental monitoring and impact assessments

In many environmental monitoring and impact assessment processes, Indigenous communities are treated as intellectually homogenous and intracultural variation in environmental knowledge often goes unaccounted for. This not only poses obvious risks to the effectiveness of environmental impact assessments but also gives standing to those who question the credibility of traditional ecological knowledge and its contribution to environmental monitoring and assessment programs altogether. In this paper we describe the steps that were taken to account for intracultural variability in First Nation knowledge of fish and the potential impacts associated with the Peace River oil sands development in Alberta, Canada. Involving the delivery of a household survey to 1,127 First Nation households in 11 Peace River communities, our approach was successful in identifying regional, community, and household variability in fishing activity, and has allowed us to differentiate novice from expert knowledge holders. This research demonstrates the need to account for intracultural variability in First Nations environmental knowledge in order for traditional ecological knowledge to make meaningful contributions to environmental monitoring and assessment programs.     

污灌区重金属污染对土壤的危害

由于土壤中重金属元素的含量对人体健康影响很大，淮阴市环境监测中心站于１９９３年至１９９７年造反某污灌区中０．６６７ｈｍ＾２的蔬菜田及其邻近的某一地下水灌区中０．６６７ｈｍ＾２的蔬菜田按梅花布点法分别布设８个测点，对其土壤中的总镉、总汞、总砷、总铬和总锅进行监测。结果表明，地下水藻区５年来综合污染指数变化不大，污染等级属安全级，说明该灌区没有受到重金属污染，而污灌区的综合污染指数逐年增高，１９９５年     

Environmental impact of coal washery and Damodar River water on the morphometry and biochemical changes of maize (Zea mays L.) and soil health

Enormous quantity of water is used for coal beneficiation and accordingly huge amount of effluents are being generated. In this study an attempt was made to evaluate the potential of this effluent water for irrigation. Water samples were collected from three different points (a) feeding point, (b) thickening point, and (c) outlet point of coal washery, and from Damodar River for monitoring the water quality. The samples were analyzed for various parameters and compared with prescribed standard, which revealed that the total suspended solids of thickening point and Damodar River were higher. A pot experiment with maize was conducted to study the suitability of this coal washery water for irrigation. Pots were irrigated with water from the three points of washery and Damodar River in two concentrations (100% and 50% dilution with distilled water); pure distilled water was used for control. There was 100% germination in all the treatments. The plant growth, chlorophyll content and soil quality parameters were significantly better in washery and Damodar River water treated pots. The Damodar River water and washery water from feeding and outlet point could be successfully used for irrigation. In general mixing with good quality water has shown better results.     

The effects of socioeconomic parameters on household solid-waste generation and composition in developing countries (a case study: Ahvaz,Iran)

Environment problems associated with the generation of waste are part of societal changes where households play an important role. These societal changes influence the size, structure and characteristic of given households. For the effective planning of solid-waste handling infrastructure, it is essential to know the quantity of waste generation and its composition. This paper presents the findings of a study carried out in an urban municipal area in Iran to determine the household solid-waste generation rate and waste composition based on field surveys and to determine the related socioeconomic parameters. The dependent variables were waste generation and composition, and independent variables were family size, family employment, age, number of room and education. Over 400 sample households were selected for the study using a stratified random sampling methodology and from five different socioeconomic groups. Waste collected from all groups of households were segregated and weighted. Waste generation rate was 5.4 kg/household/day. Household solid waste comprised of ten categories of wastes and with the largest component (76.9%). The generation and composition of household solid waste were correlated with family size, education level and households income. This paper adequately suggests new insights concerning the role of socioeconomic parameters in affecting the generation of household waste.     

Risk assessment and loading capacity of reclaimed wastewater to be reused for agricultural irrigation

The reuse of treated municipal wastewater should be one of the new water resource target areas. The suitability of the reuse of wastewater for agricultural irrigation has to consider health risk, soil contamination and the influence of the reclaimed water on crop growth. In this work the aim is to use quantitative risk analysis to assess the health effects related to reclaimed water quality and to calculate the loading capacity of reclaimed wastewater in terms of the heavy metal accumulation. The results of chemical risk assessment show there would be slightly significant health risk and what risk there is can be limited within an acceptable level. The following exposure pathway: reclaimed water-->surface water-->fish (shellfish)-->human, and arsenic risks are of more concern. In terms of reuse impact in soil contamination, the most possible heavy metal caused accumulation is arsenic. The irrigative quantity has to reach 13,300 m(3)/ha to cause arsenic accumulation. However, only 12,000 m(3)/ha is essential for rice paddy cropland. The high total nitrogen of reclaimed water from secondary treatment makes it unfavorable for crop growth. The recommended dilution ratio is 50% during the growth period and 25% during the maturity period.     

Field-scale monitoring of the long-term impact and sustainability of drainage water reuse on the west side of California's San Joaquin Valley

Diminishing freshwater resources have brought attention to the reuse of degraded water as a water resource rather than a disposal problem. Drainage water from tile-drained, irrigated agricultural land is degraded water that is often in large supply, but the long-term impact and sustainability of its reuse on soil is unknown. Similarly, nothing is known of the ramifications of terminating drainage water reuse. The objective of this study is (i) to monitor the long-term impact on soil chemical properties and thereby the sustainability of drainage water reuse on a marginally productive, saline-sodic, 32.4 ha field located on the west side of California's productive San Joaquin Valley and (ii) to assess spatially what happens to soil when drainage water reuse is terminated. The monitoring and assessment were based on spatial chemical data for soil collected during 10 years of irrigation with drainage water followed by 2 years of no applied irrigation water (only rainfall). Geo-referenced measurements of apparent soil electrical conductivity (EC(a)) were used to direct the soil sampling design to characterize spatial variability of impacted soil properties. Chemical analyses of soil samples were used (i) to characterize the spatial variability of salinity, Na, B, and Mo, which were previously identified as critical to the yield and quality of Bermuda grass (Cynodon dactylon (l.) Pers.) grown for livestock consumption and (ii) to monitor their change during the 12 year study. Soil samples were taken at 0.3 m increments to a depth of 1.2 m at each of 40 sample sites on five occasions: August 1999, April 2002, November 2004, August 2009, and May 2011. Drainage water varying in salinity (1.8-16.3 dS m(-1)), SAR (5.2-52.4), Mo (80-400 μg L(-1)), and B (0.4-15.1 mg L(-1)) was applied from July 2000 to June 2009. Results indicate that salts, Na, Mo, and B were leached from the root zone causing a significant improvement in soil quality from 1999 to 2009. Salinity and SAR returned to original levels or higher in less than two years after termination of irrigation. Boron and Mo showed significant increases. Long-term sustainability of drainage water reuse was supported by the results, but once application of irrigation water was terminated, the field quickly returned to its original saline-sodic condition.     

Effect of dehydrogenase,phosphatase and urease activity in cotton soil after applying thiamethoxam as seed treatment

Soil enzymes are indicators of microbial activities in soil and are often considered as an indicator of soil health and fertility. They are very sensitive to the agricultural practices, pH of the soil, nutrients, inhibitors and weather conditions. To understand the effect of an insecticide, thiamethoxam, on different soil enzyme activities, the experiments were conducted at cotton experimental fields of Punjab Agricultural University, Ludhiana. The results here were presented to understand the impact of thiamethoxam on soil enzyme activities. Thiamethoxam was applied as seed treatment to control the pest. Soil from three localities, i.e. soil in which seed was treated with recommended dose at 2.1 g a.i. kg^?1, soil in which seed was treated with four times recommended dose at 8.4 g a.i. kg^?1 and from the control field, were tested for different enzyme activities. Phosphatase and dehydrogenase activities were high in control soil in comparison to control soil while no effect of this insecticide on urease activity. Thiamethoxam had inhibitory effects on dehydrogenase and phosphatase activities. Therefore, it can be attributed that agricultural practices, weather conditions and use of thiamethoxam might be responsible for the different level of enzyme activities in soil.     

乌鲁木齐市米东污灌区农田土壤重金属污染评价

对米东污灌区农田土壤重金属含量进行监测分析,利用不同的评价方法和标准对土壤重金属的环境质量进行评价。结果表明:米东污灌区农田土壤重金属含量分别为Cd(0.12±0.06)mg/kg,Cu(40.43±5.30)mg/kg,Zn(78.38±11.04)mg/kg,Pb(11.66±11.79)mg/kg,Ni(20.24±8.05)mg/kg,Cr(75.81±8.05)mg/kg。以国家土壤环境质量标准(二级)为标准评价,各元素的污染指数排序为Cu>Ni>Cr>Zn>Cd>Pb,综合污染指数为0.337,污染程度为安全。以食用农产品产地土壤环境质量要求为标准评价,各元素的污染指数排序为Cu>Ni>Cr>Zn>Cd>Pb,综合污染指数为0.343,污染程度为安全。表明米东污灌区农田土壤重金属含量尚能达到食用农产品产地土壤环境质量要求。Pb、Cu、Zn的平均含量超过乌鲁木齐市土壤背景值,这说明污灌区土壤重金属Pb、Cu、Zn近年来已有所累积,存在一定的污染风险。     

IWQ Index: A GIS-Integrated Technique to Assess Irrigation Water Quality

The irrigation water quality and the associated hazards to soil characteristics and crop yield is often a complex phenomenon that involves the combined effect of many parameters. From a management point of view, it is sometimes necessary to analyze all related parameters as a combination rather than focusing on a single isolated parameter. With this objective in mind, a new GIS-integrated tool is proposed in this study to evaluate the quality of irrigation waters with regards to potential soil and crop problems. The proposed procedure is mainly an index method that utilizes five hazard groups: (a) salinity hazard, (b) infiltration and permeability hazard, (c) specific ion toxicity, (d) trace element toxicity; and, (e) miscellaneous impacts on sensitive crops. A linear combination of these groups is formulated to form the so-called IWQ index, which is a technique that could be used to classify irrigation waters with respect to three suitability classes. The proposed technique is applied to assess the irrigation water quality of the Simav Plain located in western Anatolia, Turkey. The Simav application is implemented by using a GIS database developed for the plain. Based on the results of this application, the general groundwater quality in the surfacial aquifer is found to be fairly good and the aquifer waters are mostly suitable for irrigation purposes.     

北京市通州污灌区土壤环境质量监测和蔬菜重金属污染状况研究

通过对北京市通州污灌区土壤现状调查与蔬菜重金属污染监测,结合土壤环境质量标准、食品卫生标准及污灌区污染历史,分析对比该区土壤和蔬菜重金属污染状况及其变化。结果表明,本次监测通州污灌区土壤中重金属平均含量均达到土壤环境质量标准(GB15618-1995)中二级标准限量。对照土壤中的重金属Cu、Pb、Cr、Cd和As均达到土壤一级标准。凉水河两岸和通惠北干渠中重金属含量均高于对照土壤,说明污灌区污水灌溉已使土壤受到一定程度的污染。与二十世纪70年代末监测结果相比,土壤中多数重金属含量处于上升趋势。污灌区蔬菜重金属含量监测结果表明,其含量水平均达到食品卫生标准,说明污灌区蔬菜尚未受到严重污染。     

Phosphorus losses from arable fields in Sweden—effects of field-specific factors and long-term trends

Accelerated eutrophication of surface water is often caused by high phosphorus (P) losses from agricultural fields. Long-term measurements of P concentrations from arable fields are therefore important for understanding of processes and key factors behind losses. Unfortunately, long-time series are difficult to compare due to high variablity, non-normal distribution, precipitation variability and flow relatedness. The objective was to use locally weighted scatterplot smoothing (LOWESS) and Seasonal Kendall Test to account for discharge effects on concentrations of P forms and suspended soil material, and to identify trends for seven agricultural fields included in a Swedish water quality monitoring program. Soil P content and sorption capacity governed concentrations and losses of dissolved reactive phosphorus (DRP). Other factors, such as preferential flow may influence the importance of these factors. Suspended soil material and unreactive phosphorus (UP) concentrations in water discharge depended on soil texture, slope of the field and total soil P content. Statistically significant trends in concentrations of different P forms were found for two fields. These trends are probably a consequence of changes in P additions and soils P saturation levels.     

Air Quality Improvement Estimation and Assessment Using Contingent Valuation Method, A Case Study in Beijing

The aim of the paper is to estimate and assess residents' willingness to pay to improve air quality in the urban area of Beijing using the Contingent Valuation Method (CVM). The mean willingness to pay (WTP) for a 50% reduction of harmful substances in the air was 143 CNY per household per year, and the total WTP of the residents in the study area was 336 million CNY per year. As a proportion of household annual income, the mean WTP amounted to 0.7%. Four socio-economic variables were found to have significant impacts on residents' willingness to pay. The analysis results illustrated that WTP increases with income and education level, and decreases with household population and age. The willingness was larger for residents in the urban districts than those in the suburban districts. It was found that most of the protest bids lay on interviewees' incomplete perception of the values of environmental amenity. The influence of household income on people's willingness to pay illustrated in this study reflects a causal force of Beijing's transition to market economy that households created to have disposable income are more likely to care about environmental quality. The results of this study strike an optimistic note on the possibility of measuring the total economic value of environmental quality improvement by using the CVM in China. Suggestions on implication of the CVM for both academics and policy makers are provided in the paper.