Use Of Untreated Wastewater Research Articles

Fecal Sludge Management and Sanitation Safety: An Assessment in Addis Ababa, Ethiopia.

Sanitation safety practices and risks associated with fecal sludge management are crucial for public health and the environment. This study assessed sanitation safety practices and risks in Addis Ababa, Ethiopia, at different stages of fecal sludge management. The research aimed to understand the current state of sanitation facilities, practices, and associated risks and identify areas for improvement. A mixed methods/approach was employed, utilizing household surveys, risk assessments, and sanitary inspections. A total of 384 study subjects were interviewed using face-to-face interviews and observations. The findings revealed that the majority of households (97.7%) had consistent access to toilets, with flush/pour flush toilets being the most common type (47.4%). Factors such as odors in toilets or septic tanks, open defecation by children, and the use of untreated wastewater for food production were significantly associated with sociodemographic factors. Risk assessments indicated that 67% of households fell into the low-risk category, while 33% were classified as intermediate risk. The study identified non-compliance issues during sanitary inspections at transfer stations (45%), a wastewater treatment and disposal facility (61.5%), and in the management of wastewater and sludge in the sewer line (64%). These findings call for urgent actions to address improper feces disposal, inadequate maintenance of sanitation facilities, and unsafe practices in fecal sludge management. This study identified concerning issues in fecal sludge management, including improper feces disposal, inadequate facility maintenance, and non-compliance with safety standards during emptying, transport, treatment, and disposal. Urgent action is needed to address these risks. Promoting proper disposal techniques, improving facility maintenance, education programs, strengthening regulations, providing training and protective equipment, and investing in enhanced sanitation facilities and wastewater treatment methods are essential for improving sanitation safety practices.

Morpho-anatomical adaptations of dominantly grown wild Datura inoxia to wastewater resource: Productivity and ecological issues

With the increasing global water scarcity, wastewater irrigation has become widespread, but it can have detrimental ecological consequences. Although wastewater contains valuable nutrients for plants, improper treatment or the use of untreated wastewater in irrigation can negatively impact soil fertility and plant growth. This study is divided into two parts: firstly, a phytosociological survey was conducted to identify plant species with the highest importance value index (IVI) in the vicinity of wastewater-irrigated areas. Secondly, a comparative morpho-anatomical analysis was carried out to investigate the morpho-anatomical adaptations of the species with the highest IVI under wastewater irrigation compared to normal water irrigation. The results of the phytosociological survey revealed the presence of 51 plant species in the vicinity of the wastewater-irrigated areas, with varying relative densities and coverage. Datura inoxia exhibited the highest IVI (28.79), followed by Xanthium strumarium (24.34), while Lippia nodiflora showed the lowest IVI (1.86). The morphological growth of D. inoxia was superior under normal water irrigation, but the average root length was greater under wastewater irrigation. Regarding cell anatomy, cell thickness and cell area characteristics in the dermal, ground, and vascular tissues of the stem and root tended to be greater under wastewater treatment. However, the opposite trend was observed in leaf anatomical analysis, possibly due to the combined effect of wastewater and climatic conditions. Stem and root xylem thickness were greater under wastewater irrigation, whereas phloem thickness was higher under normal water irrigation. The number of vascular bundles in the stem, root, and leaf was higher under wastewater treatment compared to normal water irrigation, but their arrangement was circular in the latter and scattered under wastewater irrigation. Datura inoxia demonstrated strong adaptive potential under wastewater irrigation, as indicated by its highest relative density, coverage, and IVI, suggesting its suitability for phytoremediation. However, due to the low relative density, coverage, and IVI of many other species, the use of untreated wastewater for irrigation cannot be appreciated.

The Prevalence of Aeromonas Species in Salad Vegetables Sourced from Four Local Government Areas of Plateau State

The current study was conducted to determine the prevalence of Aeromonas species in five salad vegetables, namely lettuce, cabbage, carrot, cucumber, and green pepper, in four local government areas of Plateau state. Aeromonas species have been linked to a number of gastroenteritis outbreaks connected to the consumption of contaminated fresh vegetables and fruits. In Nigeria, the use of untreated wastewater in irrigation is often regarded as an unavoidable alternative for compensating for water scarcity. This study was conducted to determine the prevalence of Aeromonas species in salad vegetables from four local government areas of Plateau State. 800 lettuce samples, including 160 lettuces, 160 cabbages, 160 carrots, 160 cucumbers and 160 green peppers, were analyzed for the presence of Aeromonas species using standard isolation, identification and characterization methods. Of the 800 samples, 202 samples were positive. Aeromonas spp. was isolated from 60(7.50%) lettuce samples, 52(6.50%) cabbage samples, 35(4.38%) carrot samples, 30(3.77%) cucumber samples and 25(3.12%) green pepper samples making lettuce the vegetable with the highest prevalence of the organism. According to the findings, samples of salad vegetables from Lamingo had the highest percentage prevalence of Aeromonas species, at 45 (6.25%), followed by samples from Miango, at 42 (5.25%), and samples from Vom, at 37 (4.64%) had the lowest percentage prevalence of the organism. According to the statistical analysis's findings, the prevalence of the organism in various vegetable types with relation to the study locations did not differ significantly (p>0.05) at the 95% confidence level. The incidence of Aeromonas species isolated from the various study regions varied significantly depending on the season, with the organism being more prevalent during the wet season (3.7%) than during the dry season (1.35%).

Groundwater Quality Modeling and Mitigation from Wastewater Used in Irrigation, a Case Study of the Nile Delta Aquifer in Egypt.

Groundwater is an essential freshwater source because traditional sources of freshwater, such as rainfall and rivers, are unable to provide all residential, industrial, and agricultural demands. Groundwater is replenished by different sources: rivers, canals, drains, and precipitation. This research aims to apply numerical models for a real case study (Bahr El Baqar drain) in the Eastern Nile aquifer to monitor groundwater quality due to the use of wastewater from drains directly in irrigation due to the shortage of freshwater in this area. In addition, the effect of over-pumping from the aquifer is studied to show the extent of contaminants in groundwater. Moreover, a management strategy was achieved through mixing treated wastewater with freshwater to reduce the contamination of groundwater and overcome water shortage. Visual MODFLOW is used to simulate groundwater flow and contaminant transport into the Eastern Nile aquifer (ENDA), Egypt. In this study, three stages including 15 scenarios (five scenarios for each stage) were settled to achieve the study objectives. The first stage was carried out to investigate the impact of using untreated wastewater for irrigation due to the shortage of freshwater in this area. The results of this stage showed that increasing the use of untreated wastewater increased the contamination of the aquifer. The average COD concentrations in the five scenarios reached 23.73, 33.76, 36.49, 45.13, and 53.15 mg/L. The second stage was developed to evaluate the impact of over-pumping and using untreated wastewater for irrigation due population increase and a reduction of freshwater in the Nile Delta. The results revealed that over-pumping has increased the contamination of the aquifer and the average COD concentrations increased to 25.3, 33.34, 40.66, 48.6, and 54.17 mg/L. The third stage was applied to investigate the impact of mixing treated wastewater with freshwater for irrigation to support the freshwater quantity. The results of this stage led to enhanced water quality in the aquifer and the average COD concentrations decreased to 20.26, 23.13, 26.03, 30, and 32.83 mg/L. The results showed that mixing freshwater with treated wastewater has a good influence on water quality, can be safely used in irrigation and reduces the effects on farmers' health and life.

Potential Use of Untreated Wastewater for Assessing COVID-19 Trends in Southern Italy.

As a complement to clinical disease surveillance, the monitoring of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in wastewater can be used as an early warning system for impending epidemics. This study investigated the dynamics of SARS-CoV-2 in untreated wastewater with respect to the trend of coronavirus disease 2019 (COVID-19) prevalence in Southern Italy. A total of 210 wastewater samples were collected between May and November 2020 from 15 Apulian wastewater treatment plants (WWTP). The samples were concentrated in accordance with the standard of World Health Organization (WHO, Geneva, Switzerland) procedure for Poliovirus sewage surveillance, and molecular analysis was undertaken with real-time reverse-transcription quantitative PCR (RT-(q) PCR). Viral ribonucleic acid (RNA) was found in 12.4% (26/210) of the samples. The virus concentration in the positive samples ranged from 8.8 × 102 to 6.5 × 104 genome copies/L. The receiver operating characteristic (ROC) curve modeling showed that at least 11 cases/100,000 inhabitants would occur after a wastewater sample was found to be positive for SARS-CoV-2 (sensitivity = 80%, specificity = 80.9%). To our knowledge, this is the first study in Italy that has applied wastewater-based epidemiology to predict COVID-19 prevalence. Further studies regarding methods that include all variables (meteorological phenomena, characteristics of the WWTP, etc.) affecting this type of wastewater surveillance data would be useful to improve data interpretation.

Heavy Metal Contamination in Green Leafy Vegetables Irrigated with Wastewater Collected from Harar Town Vegetable Farm, Ethiopia

Food safety issues are of growing concern to consumers globally because of the risks associated with consumption of foods contaminated with heavy metals. In Harar town, Kebele 05 vegetable farm is known to produce vegetables irrigated with wastewater. To what extent these vegetables are contaminated with heavy metals was not known. Thus, a laboratory based cross sectional study was conducted from October 2016 to January 2017 to assess the extent of heavy metal contamination of vegetables. Accordingly, a total of 72 samples from four leafy vegetables namely lettuce (Lactuca sativa), spinach (Spinacea oleracea), kale (Brassica carinata)) and cabbage (Brassica oleracea) were determined. Lead (Pb), Cadmium (Cd), and Chromium (Cr) concentration was determined using atomic absorption spectrophotometry. In all the vegetables, the mean concentrations of Pb, Cd and Cr were 0.17, 0.62 and 1.78 mg/kg, respectively in all vegetables. Cd was found in level more than the maximum limit recommended by FAO/WHO but the level of lead was within the normal range for all vegetables. Chromium was found also within the normal range in all vegetables except in lettuce. The findings of this study have important information on the implications of public health by sequestration of heavy metals to these leafy vegetables then to among vegetable consumers of Harar town and the surroundings. Thus, it is recommended that the concerned public health authorities need to create awareness in the community and discouraging the use of untreated wastewater for cultivating vegetables. Keywords: Contamination, Heavy metal, Vegetables, Wastewater DOI: 10.7176/FSQM/94-03 Publication date: February 29 th 2020

Seroepidemiology of human toxocariasis in North Africa.

Seroprevalence studies on human toxocariasis help to assess the burden and the morbidity associated with this zoonosis. This review searched the seroprevalence studies and case reports in six North African countries: Algeria, Egypt, Libya, Morocco, Sudan and Tunisia, since 1990. The search also included studies on the environmental factors related to the risk of transmission. Most of the published epidemiological studies were done in Egypt. Cross-sectional and case-control studies in Egypt demonstrated that toxocariasis is a significant zoonosis that could be associated with conditions like bronchial asthma allergies and certain neuropsychiatric disorders. The population at risk of this infection includes all ages, both genders, in contact with dogs, resident in rural areas with poor housing conditions. The publications from Tunisia, Morocco and Algeria are limited to case reports and retrospective analyses of cases, but the disease is probably under-diagnosed in these three countries. There are no published reports on human toxocariasis in Libya and Sudan during the period covered by the review. Animal studies confirm high infection rates of dogs with Toxocara canis in North Africa. There is also evidence of wide-spread contamination of soil and water with Toxocara spp. eggs. Moreover, the use of untreated wastewater for irrigation in parts of North Africa could be a source of contamination of agricultural products with eggs of Toxocara spp. Population-based studies on human toxocariasis are recommended, using standardized diagnostic tests. These surveys should also assess risk factors to guide preventive measures.

Impact of climate change on raw and untreated wastewater use for agriculture, especially in arid regions

Impact of climate change on raw and untreated wastewater use for agriculture, especially in arid regions

Presence and Natural Treatment of Organic Micropollutants and their Risks after 100 Years of Incidental Water Reuse in Agricultural Irrigation

The aim of the research was to show the presence of micropollutants contained in the wastewater of Mexico City within the distribution canals of the Mezquital Valley (MV), as well as their retention in agricultural soil and aquifers. This system constitutes the world’s oldest and largest example of the use of untreated wastewater for agricultural irrigation. The artificial recharge associated with the MV aquifers, with groundwater extracted for human consumption showing its importance as a water resource for Mexico City. The results of sampling show the presence of 18 compounds, with 10 of these considered as endocrine disruptor compounds (EDCs). The concentration of these pollutants ranged from 2 ng/L for 17 β-estradiol to 99 ng/L for DEHP, with these values decreasing throughout the course of the canals due to the wastewater dilution factor, their retention in agricultural soil, and their accumulation in the local aquifer. The main mechanisms involved in natural attenuation are adsorption, filtration, and biodegradation. Drinking water equivalent levels (DWELs) were estimated for 11 compounds with regard to acceptable daily intakes (ADIs), by assuming local exposure parameters for a rural Mexican population. These were compared with the maximum groundwater concentrations (Cgw) to screen the potential risks. The very low ratios of Cgw to DWELs indicate no appreciable human health risk from the presence of trace concentrations of these compounds in the source of drinking water in the MV. Despite this, far from being exceeded after more than 100 years of irrigation with residual water, the natural soil attenuation seems to remain stable.

Consumers’ willingness to pay for safer vegetables in Tamale, Ghana

Consumers’ concerns over misuse of agrochemicals and untreated wastewater for irrigation in vegetable production are increasing demand for safer vegetables in urban cities. Providing safer vegetables requires production methods that minimize or eliminate the associated risks. Nevertheless, these practices involve extra cost, which requires that consumers, at least, bear part of the cost. The main objective of this paper is to examine factors influencing consumers’ willingness to pay price premiums for safer vegetables. We sampled a cross-section of 331 consumers in Tamale, and elicited their willingness to pay premium prices for safer vegetables. The results show that consumers are willing to pay average premiums of GH¢8.01 (US$1.90), GH¢3.27 (US$0.78) and GH¢2.89 (US$0.69) for standard quantities of safer cabbage, safer ayoyo and safer okra, respectively. These premium prices are equivalent to 128.6%, 197.3% and 189.0% of the current average market prices of same quantities of the conventional vegetables. Typically, consumers willing to pay premium prices are those with income generating employment, have trust in traders and care about the use of untreated wastewater for irrigation. These findings mean that consumers are generally willing to bear extra cost to secure consumption of safer vegetables, and avoid health-related risks associated with unsafe, conventional vegetables.

A Review of Environmental Contamination and Health Risk Assessment of Wastewater Use for Crop Irrigation with a Focus on Low and High-Income Countries.

Population densities and freshwater resources are not evenly distributed worldwide. This has forced farmers to use wastewater for the irrigation of food crops. This practice presents both positive and negative effects with respect to agricultural use, as well as in the context of environmental contamination and toxicology. Although wastewater is an important source of essential nutrients for plants, many environmental, sanitary, and health risks are also associated with the use of wastewater for crop irrigation due to the presence of toxic contaminants and microbes. This review highlights the harmful and beneficial impacts of wastewater irrigation on the physical, biological, and chemical properties of soil (pH, cations and anions, organic matter, microbial activity). We delineate the potentially toxic element (PTEs) build up in the soil and, as such, their transfer into plants and humans. The possible human health risks associated with the use of untreated wastewater for crop irrigation are also predicted and discussed. We compare the current condition of wastewater reuse in agriculture and the associated environmental and health issues between developing and developed countries. In addition, some integrated sustainable solutions and future perspectives are also proposed, keeping in view the regional and global context, as well as the grounded reality of wastewater use for crop production, sanitary and planning issues, remedial techniques, awareness among civil society, and the role of the government and the relevant stakeholders.

Survey of 218 organic contaminants in groundwater derived from the world's largest untreated wastewater irrigation system: Mezquital Valley, Mexico

The Mezquital Valley system is the world's oldest and largest example with regard to use of untreated wastewater for agricultural irrigation. Because of the artificial high recharge associated with the Mezquital Valley aquifers, groundwater is extracted for human consumption, and there are plans to use this groundwater as a water resource for Mexico City. Thus, this study analyzed 218 organic micro-contaminants in wastewater, springs, and groundwater from Mezquital Valley. Five volatile organic compounds (VOCs) and nine semi-volatile organic compounds (SVOCs) were detected in the wastewater used for irrigation. Only two SVOCs [bis-2-(ethylhexyl) phthalate and dibutyl phthalate] were detected in all the wastewater canals and groundwater sources, whereas no VOCs were detected in groundwater and springs. Of the 118 pharmaceutically active compounds (PhACs) and 7 reproductive hormones measured, 65 PhACs and 3 hormones were detected in the wastewater. Of these, metformin, caffeine, and acetaminophen account for almost sixty percent of the total PhACs in wastewater. Nevertheless, 23 PhACs were detected in groundwater sources, where the majority of these compounds have low detection frequencies. The PhACs sulfamethoxazole, N,N-diethyl-meta-toluamide, carbamazepine, and benzoylecgonine (primary cocaine metabolite) were frequently detected in groundwater, suggesting that although the soils act as a filter adsorbing and degrading the majority of the organic pollutant content in wastewater, these PhACs still reach the aquifer. Therefore, the presence of these PhACs, together with the high levels of the endocrine disruptor bis-2-(ethylhexyl) phthalate, indicate that water sources derived from the recharge of the studied aquifers may pose a risk to consumer health.

The Impact of Climate Change on Raw and Untreated Wastewater Use for Agriculture, Especially in Arid Regions: A Review.

Climate change is one of the major challenges of our time that pose unprecedented stress to the environment and threats to human health. The global impacts of climate change are vast, spanning from extreme weather events to changes in patterns and distribution of infectious diseases. Lack of rainfall associated with higher temperatures has a direct influence on agricultural production. This is compounded by a growing population forecasted to expand further with increasing needs for food and water. All this has led to the increasing use of wastewater worldwide. In this review, we more specifically discuss the use of untreated wastewater in agriculture in the Middle East and North Africa (MENA) countries, the most arid region in the world. This presents challenges for agriculture with respect to water availability and increasing wastewater use in agri-food chain. This in turn exerts pressures on the safety of food raised from such irrigated crops. Current practices in the MENA region indicate that ineffective water resource management, lack of water quality policies, and slow-paced wastewater management strategies continue to contribute to a decline in water resources and an increased unplanned use of black and graywater in agriculture. Radical actions are needed in the region to improve water and wastewater management to adapt to these impacts. In this regard, the 2006 WHO guidelines for the use of wastewater contain recommendations for the most effective solutions. They provide a step-by-step guide for series of appropriate health protection measures for microbial reduction targets of 6 log units for viral, bacterial, and protozoan pathogens, but these need to be combined with new varieties of crops that are drought and pest resistant. More research into economic local treatment procedures for wastewater in the region is warranted.

A global, spatially-explicit assessment of irrigated croplands influenced by urban wastewater flows

When urban areas expand without concomitant increases in wastewater treatment capacity, vast quantities of wastewater are released to surface waters with little or no treatment. Downstream of many urban areas are large areas of irrigated croplands reliant on these same surface water sources. Case studies document the widespread use of untreated wastewater in irrigated agriculture, but due to the practical and political challenges of conducting a true census of this practice, its global extent is not well known except where reuse has been planned. This study used GIS-based modeling methods to develop the first spatially-explicit estimate of the global extent of irrigated croplands influenced by urban wastewater flows, including indirect wastewater use. These croplands were further classified by their likelihood of using poor quality water based on the spatial proximity of croplands to urban areas, urban wastewater return flow ratios, and proportion of wastewater treated. This study found that 65% (35.9 Mha) of downstream irrigated croplands were located in catchments with high levels of dependence on urban wastewater flows. These same catchments were home to 1.37 billion urban residents. Of these croplands, 29.3 Mha were located in countries with low levels of wastewater treatment and home to 885 million urban residents. These figures provide insight into the key role that water reuse plays in meeting the water and food needs of people around the world, and the need to invest in wastewater treatment to protect public health.

Wastewater Confronting Realities for Sustainable Livelihood in Developing Countries: Case Study Mekelle University, Ethiopia

Water is becoming a scarce resource in terms of quantity and quality. Water supply enhancement measures are being taken with less attention given to wastewater management, leading to increased discharge of untreated wastewaters. Wastewater is emerging as an affordable and reliable alternative water supply for urban agriculture, supporting thousands of farmers. Extensive use of untreated wastewater for irrigation will without a doubt lead to accumulation of heavy metals in soils and crops, resulting in overwhelming risks to both public health and the environment. This paper deals with determination of the strength and compositions of the wastewater from a public university in the tropical semiarid region for rainy and dry seasons, based on a number of key parameters including heavy metals. Furthermore, it identified the real advantages of treated water use and issues pertaining to untreated wastewaters use for irrigation purposes. An independent t test showed significant differences in concentrations of all the tested metals, excluding lead, copper, and cadmium during dry and wet seasons. Similarly, differences were significant for electrical conductivity, biological oxygen demand, total nitrogen and total phosphorus. Salinity and concentrations of organics, nutrients, copper, cadmium, iron, manganese and to some extent copper exceeded the allowable thresholds for irrigation water. Lead, zinc, nickel and chromium, on the other hand, were lower than their respective limits. Wastewater used for irrigation purposes is unsafe, and urgent policy interventions on the use of untreated wastewater are required.

Monitoring of indicator and multidrug resistant bacteria in agricultural soils under different irrigation patterns

The presence of multidrug-resistant bacteria has been proposed as an environmental impact indicator of wastewater use in agricultural soils. Nevertheless, the effect of untreated wastewater discharge on occurrence and persistence of these type of bacteria in soils is unclear. In this study, multidrug-resistant bacteria and microbial indicators of fecal contamination (coliforms and Salmonella) were determined at different depths (0–15, 15–30 and 30–50cm), in active agricultural soils under different untreated wastewater irrigation pattern (a zone with past and present wastewater irrigation; a zone with wastewater irrigation until 2003; and a zone that had never been irrigated with wastewater) in Chihuahua, Mexico. A total of 94 multidrug-resistant strains were recovered from all tested soil samples, even from those that have never been irrigated with wastewater. Higher presence (P<0.05) of multidrug-resistant bacteria was found in soils currently irrigated with untreated wastewater than in soils that has not been irrigated with wastewater for more than 10 years; the later had presence of multidrug-resistant bacteria that was statistically higher than soils that had never been irrigated with wastewater. Wastewater irrigation showed an impact on proliferation of antibiotic-resistant Gram negative bacteria in soils actually irrigated but not in Gram positive bacteria. No statistical difference was found for coliforms and Salmonella between the three soil groups. The effect of depth in multidrug-resistance bacteria presence was negligible. Although multidrug-resistant bacteria was also isolate from soils without wastewater irrigation, their persistence in a highest number in soils irrigated with wastewater suggest that use of untreated wastewater for irrigation enhance the proliferation of multidrug-resistant microorganisms which can be monitoring in soils even after a long period of time after the last irrigation.

Pesticide or wastewater: Which one is a bigger culprit for acute health symptoms among vegetable growers in Pakistan's Punjab?

ABSTRACTLiterature highlights harmful effects of pesticides and untreated wastewater use on farmers' health but none of the studies explore the magnitude of deleterious health effects simultaneously. The objective of the study is to quantify pesticide and untreated wastewater induced health symptoms among vegetable growers and to investigate which one is a bigger culprit. A sample of 830 vegetable growers was selected by stratified random sampling from three major vegetable growing districts of Pakistan's Punjab. A two stage estimation technique is employed to estimate unbiased health effects of vegetable growers after controlling for pesticide endogeneity. The results demonstrate that both untreated wastewater and pesticide quantities are responsible for acute symptoms, but comparison of their scaled coefficients indicates that wastewater is twofold responsible for acute symptoms than pesticide. To minimize these negative effects, a policy of untreated disposal of wastewater in peri-urban areas for crop production needs to be re-designed. The installation of a treatment plant by collecting pollution premium from untreated wastewater emitters seems to be the most sustainable and practically viable option. It is also observed that pesticide is contributing to farmers' acute symptoms; hence, awareness campaigns about judicious and safe use of pesticides may help to mitigate acute symptoms.

Prevalence and antimicrobial susceptibility of pathogenic Escherichia coli O157 in fresh produce obtained from irrigated fields

Escherichia coli O157 has been implicated in many outbreaks of gastroenteritis associated with the consumption of contaminated fresh vegetables, fruits and sprouts. In Nigeria, the use of untreated wastewater in irrigation is largely considered an inevitable option to compensate for water shortages. This study investigated the seasonal prevalence and antimicrobial susceptibility of potentially pathogenic E. coli O157 from fresh produce in two large vegetable producing areas in Nigeria (Kano and Plateau States). Four hundred and forty samples, comprising fresh produce (238), irrigation water (84), and soil/manure samples (118) were collected from May, 2010 to March 2011, and analyzed for the presence of potentially pathogenic E. coli O157. Overall, 7.3% (32/440) samples were identified as E. coli O157 with its highest detection from Kano State 18/230 (12.2%). E. coli O157 was 3 times higher in vegetables during wet season than dry season and 2.3 times higher in irrigation water in wet season than in dry season. E. coli O157 was tested for their susceptibility to eight commonly used antibiotics and by Polymerase Chain Reaction (PCR) for the presence of; uidA, O157 and genes coding for the quinolone resistance-determining region (gyrA) and plasmid (pCT) coding for multidrug resistance. The confirmed isolates showed that 30/32 (93.8%) were resistant to two or more antibiotics distributed in seven different multidrug resistance patterns. Our results reflect occurrence of multidrug resistant E. coli O157 in these major produce regions. We recommend adequate treatment of wastewater before use to avoid possible public health hazards from consumption of these vegetables.

미처리하수지구 논에서의 수질 및 토양 특성 분석

The objectives of this study were to monitor and analyse water quality and soil property in paddy fields where untreated wastewater is irrigated. Three paddy fields where streamflow mixed with untreated wastewater has been irrigated (untreated wastewater district, UWD) were selected for monitoring, and five paddy fields in Yongin area (Yongin district, YID) where water from Idong agricultural reservoir (well-managed) has been irrigated were selected for comparative evaluation. Electronic conductivity (EC), suspended solids (SS), total nitrogen (T-N), total phosphorous (T-P), <TEX>$NO_3-N$</TEX>, <TEX>$Ca^{2+}$</TEX>, <TEX>$Mg^{2+}$</TEX>, <TEX>$Na^+$</TEX>, total coliform (TC), fecal coliform (FC), and E. coli of the irrigation water in the UWD were significantly higher than those in the YID. Relatively high concentrations of EC, T-N, T-P, TC, FC, E. coli, copper (Cu), lead (Pb), zinc (Zn), and aluminium (Al) were shown in the irrigation water of the UWD especially during May to June. In general, the paddy soil in the UWD contained more Pb, Zn, and Cu than in the YID although the soil heavy metal contents in the UWD still meet the Korean soil contamination warning standards. No temporal trends in the heavy metal concentrations were found in paddy soils of the UWD. This study showed that the use of untreated wastewater to paddy fields has the possibility of negative impacts on water quality and soil, although long-term monitoring is needed to fully evaluate its effects.

L'HORTICULTURE URBAINE A OUAGADOUGOU: CARACTERISATION ET PROSPECTIVE

Horticulture in urban areas is a solution to real problems such as food security, unemployment, social integration, environment issues, green space creation and so on. Nevertheless, in spite of its vital functions in developing countries, urban horticulture suffers from a lack of recognition and carries little economic weight. This is explained by its use of scarce resources and the health and environmental risks associated with its practice. This situation is well put in evidence in the specific case of Ouagadougou in Burkina Faso, the city that features as the subject of field research conducted for this article. The study aims at making a forward-looking analysis of the agricultural activity in this city and to supply information for the decision-making support relative to its expansion. The characterization made from field data unveils an activity dominated by truck farming that provisions the urban markets of the city with more than 90% of its intake of fruits and vegetables. Truck farmers are subjected to the scarcity and controversial availability of land and water resources, as well as to the rudimentary character of the equipments used, the poor quality of soils, and the health risks associated with the use of untreated waste water, chemical fertilizers and pesticides. The skills of Ouagadougou’s farmers are not adequate enough to sustain a prosperous agricultural activity. Indeed, most of them had no formal schooling or training and do not have the required knowledge of agro-pedagogical, economic, environmental and sanitary issues. The key challenge facing the development of the agricultural activity in Ouagadougou is land use and access and the insecurity that deters investors from committing resources to the development of the sector. A spatial inventory reveals the existence of 102 agricultural sites distributed on 35 zones. This inventory proves that far from receding or being pushed aside, the agricultural activity does not stop growing in spite of a quasi-ban due to the “fuzzy” legal character that surrounds it and the constraints that characterizes it. The adoption of the SDAGO horizon 2025, a national large-scale document adopted during the Council of Ministers, designates green spaces to be rehabilitated on the municipality’s territory. It is then the ideal springboard to give to this space all its enriching functions and turn urban horticulture in Ouagadougou into a practice that can contribute to the to the real construction of Mougeot’s (2006) agricultural cities or cities of the future.