Irrigation Of Food Crops Research Articles

Wastewater reclamation by advanced treatment of secondary effluents

The objectives of this study were the investigation of the performance of an advanced treatment system, for the reclamation of secondary municipal effluents, and the study of the environmental quality of treated effluents. The secondary effluents from a conventional activated sludge process were fed to an advanced wastewater treatment system, consisting of a moving-bed sand filter, a granular activated carbon adsorption bed and ozone disinfection. The performance of this plant was evaluated by measuring the physicochemical, microbiological and ecotoxicological characteristics of reclaimed water. Sand filtration resulted in about 45% turbidity removal, while carbon adsorption enhanced mainly the removal of organic content, i.e. the total organic carbon removal exceeded 80%. The quality of treated effluents, obtained after ozonation by an ozone dosage of 26.7 mg/L, was found to comply with the respective US EPA proposed guidelines for urban reuse, food crop irrigation and recreational impoundments. However, a high ozone dose caused adverse effects on bacterium V. fischeri, possibly due to the formation of secondary oxidation byproducts. The annual cost of overall tertiary treatment process was evaluated to 0.24 €/m 3, indicating the relatively high cost of these processes. Nevertheless, such processes are required in order to produce an effluent, with a high reuse potential.

Study of the bacteriological and physicochemical indicators of pollution of surface waters in Zaria, Nigeria

This study investigates the pollution level of surface waters in Zaria, Nigeria. The bacteriological and physicochemical analyses performed were in accordance with standard procedures. Out of 228 samples from different sites, 128 (56.1%) had counts higher than the standards. Samaru stream was the most polluted. The frequency of contamination of samples with Escherichia coli O157 was only 2.2%. There was a positive correlation between faecal coliform count with most of the physicochemical parameters. The use of the surface waters as raw water for drinking, irrigation of food crops for raw consumption and for recreational activities may be hazardous. The study therefore, stresses on the need to control the faecal pollution of the bodies of water.

Effect of Irrigation Method on Transmission to and Persistence of Escherichia coli O157:H7 on Lettuce

In this study, the transmission of Escherichia coli O157:H7 to lettuce plants through spray and surface irrigation was demonstrated. For all treatments combined, the number of plants testing positive following a single exposure to E. coli O157: H7 through spray irrigation (29 of 32 plants) was larger than the number testing positive following surface irrigation (6 of 32 plants). E. coli O157:H7 persisted on 9 of 11 plants for 20 days following spray irrigation with contaminated water. Immersion of harvested lettuce heads for 1 min in a 200 ppm chlorine solution did not eliminate all E. coli O157:H7 cells. The results of this study suggest that regardless of the irrigation method used, crops can become contaminated; therefore, the irrigation of food crops with water of unknown microbial quality should be avoided.

Hygienic Evaluation of Reclaimed Water Used to Irrigate Food Crops—A Case Study

The study was designed to test the continued validity of a field pilot project (completed in 1987) that had found irrigation of food crops with tertiary-treated reclaimed municipal wastewater to be safe. It was also designed to determine whether or not pathogenic microorganisms of concern to food safety, such as E. coli 0157:H7, Cyclospora, enteric viruses and Salmonella were present in disinfected tertiary recycled water. Sampling of the tertiary water was conducted at intervals over a period of three months. In addition, at the same time, samples were taken from the raw incoming wastewater, from secondary effluent, and from a control source, local well water. The results from samples of recycled water are comparable to similar tests at other well-operated, tertiary recycled water treatment plants and compare well with sources of drinking water supply. Other parasites, of lesser concern to food safety than to drinking water safety, were either absent or were detected at extremely low concentrations of empty, non-viable cysts. The Tertiary Water Food Safety Study did not detect any Salmonella, Cyclospora and E. coli 0157:H7 in any of the samples of tertiary recycled water from the Monterey Country Water Recycling Projects (MCWRP).

Classification of explosives transformation products in plant tissue

AbstractExplosives contamination in surface or groundwater used for the irrigation of food crops and phytoremediation of explosives‐contaminated soil or water using plant‐assisted biodegradation have brought about concerns as to the fate of explosives in plants. Liquid scintillation counting, high‐performance liquid chromatography, and gel permeation chromatography were utilized to characterize explosives (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine and trinitrotoluene) and their metabolites in plant tissues obtained from three separate studies. Analyzing tissues of yellow nutsedge (Cyperus esculentus), corn (Zea mays), lettuce (Lacuta sativa), tomato (Lyopersicum esculentum), radish (Raphanus sativus), and parrot feather (Myriophyllum aquaticum) from three studies where exposure to explosives at nontoxic levels (1–2 mg/L in water) occurred showed that extensive transformation of the explosive contaminant occurred, variations were noted in uptake and transformation between terrestrial and aquatic plants, the products had significantly higher polarity and water solubility than the parent compounds, and the molecular sizes of the transformation products were significantly greater than those of the parent compounds (approximately 300 times greater).

Hygienic evaluation of reclaimed water used to irrigate food crops — A case study

The study was designed to test the continued validity of a field pilot project (completed in 1987) that had found irrigation of food crops with tertiary-treated reclaimed municipal wastewater to be safe. It was also designed to determine whether or not pathogenic microorganisms of concern to food safety, such as E. coli 0157:H7, Cyclospora, enteric viruses and Salmonella were present in disinfected tertiary recycled water. Sampling of the tertiary water was conducted at intervals over a period of three months. In addition, at the same time, samples were taken from the raw incoming wastewater, from secondary effluent, and from a control source, local well water. The results from samples of recycled water are comparable to similar tests at other well-operated, tertiary recycled water treatment plants and compare well with sources of drinking water supply. Other parasites, of lesser concern to food safety than to drinking water safety, were either absent or were detected at extremely low concentrations of empty, non-viable cysts. The Tertiary Water Food Safety Study did not detect any Salmonella, Cyclospora and E. coli 0157:H7 in any of the samples of tertiary recycled water from the Monterey County Water Recycling Projects (MCWRP).

Estimating the safety of wastewater reclamation and reuse using enteric virus monitoring data

The reliability of wastewater reclamation and reuse to meet a given annual risk of infection, considering the variability of enteric virus concentrations, has been investigated. Two concepts related to the reliability and safety of wastewater reclamation and reuse are presented. The first is reliability, defined as the probability that the risk of infection from enteric viruses in reclaimed wastewater does not exceed an acceptable risk. The second is based on the expectation of the acceptable annual risk in which the exposure to enteric viruses may be estimated stochastically by numerical simulation. To assess the potential risks associated with the use of reclaimed wastewater in various reuse applications, four exposure scenarios were tested: golf course irrigation, food crop irrigation, recreational impoundments, and groundwater recharge. Past monitoring data on enteric virus concentrations in unchlorinated secondary effluents in California were used. Because enteric virus concentrations in unchlorinated secondary effluents were found to vary over a wide range, characterizing their variability was found to be extremely important. The reliability criterion of meeting the less than 10−4 annual risk of infection (less than or equal to one infection per 10 000 population per year) at least 95% of the time was used to assess the safety of using reclaimed wastewater in the four different exposure scenarios. The methodologies used in this study should be refined, based on a larger enteric virus database developed using standardized field and laboratory protocols.

Radiation exposure from radionuclides in ground water: an uncertainty analysis for selected exposure scenarios.

The uncertainty of the potential radiation exposure of the general population has been estimated for a normalized contamination of ground water that is being used as drinking water for humans and animals, for irrigation of food and feed crops, and for fish production in freshwater bodies. The frequency distributions of annual effective dose equivalents were calculated assuming a normalized activity concentration in water of 1 Bq/l for each radionuclide considered. Estimated frequency distributions of the parameters were used as model input. This estimation is based on an exposure scenario which reflects the present radioecological conditions. Another important source for the uncertainty of the potential dose due to radionuclides released to the ground water is the uncertainty of the exposure scenario. Since such a contamination may not occur before some time in the far future, it is impossible to predict the exact boundary conditions. Therefore, scenarios were stimulated with modified consumption habits, more extensive farm management and different climatic conditions. The distributions of the potential doses cover in general about a factor of 10-20. The intake of drinking water, the root uptake and the contamination of fish are most important for the resulting potential radiation exposure. For nearly all radionuclides, the intake of drinking water dominates the potential exposure. In most cases radioactive daughter nuclides are of minor importance. In general, the influence of the exposure scenario on the dose is relatively small.

Evaluation of the California Wastewater Reclamation Criteria Using Enteric Virus Monitoring Data

The State of California's WastewaterReclamationCriteria is under review and will be revised and expanded to include several new regulations on the use of reclaimed municipal wastewater. To provide a scientific basis for the evaluation of the existing and proposed Criteria, enteric virus monitoring data from secondary and tertiary effluents were evaluated. These virus data were obtained from special studies and monitoring reports, covering the period from 1975 to 1989, including ten municipal wastewater treatment facilities in California. Based on the enteric virus data from these reports, and using the current Criteria as a guide, four exposure scenarios were developed to determine the risk of waterborne enteric virus infection to humans as a consequence of wastewater reclamation and reuse. The exposure assessments included food crop irrigation, landscape irrigation for golf courses, recreational impoundments, and ground water recharge. The virus enumeration and the resulting risk assessments described in this paper provide a comparative basis for addressing the treatment and fate of enteric viruses in wastewater reclamation and reuse. The analyses show that annual risk of infection from exposure to chlorinated tertiary effluent containing 1 viral unit/100 L in recreational activities such as swimming or golfing is in the range of 10−2 to 10−7, while exposures resulting from food-crop irrigation or groundwater recharge with reclaimed municipal wastewater is in the range of 10−6 to 10−11. The risk analyses are also used to demonstrate that the probability of infection can be further mitigated by controlling exposure to reclaimed wastewater in the use area.

Cholera in Peru

Between January 1991 and March 1992 more than 400000 people suffered from cholera and more than 3100 died in Peru. Perus well-developed national transportation system facilitated the spread of cholera to all areas of the country. It may not have spread so quickly and efficiently however had sufficient environmental health conditions existed and had people practiced good personal hygiene. Most cholera cases lived in poor areas with no public service infrastructure e.g. water supply sanitation and solid waste disposal. A study of water supply systems reveals only 2 of 40 chlorinated systems and none of the 20 simple gravity systems were satisfactory. Even though oral rehydration therapy and antibiotics reduce the severity of cholera and prevent death environmental health measures to prevent contamination of food and water (including ice) and promotion of good personal hygiene are the most effective means to stop the spread of cholera and sustain its prevention. Contamination of food with Vibrio cholerae can occur via handling and processing of food even when the dose is not enough to cause illness because some foods (e.g. animal products and rice) promote V. cholerae growth. Sewage water used to irrigate food crops is another contamination source. Inadequately washed glasses plates and utensils by food vendors are yet another source. The most inexpensive and effective disinfectant against V. cholerae is chlorine. Even though boiling water does kill V. cholerae it has no residual protection against recontamination and is more expensive than chlorine. The Peruvian government has stepped up programs to disinfect community water systems and is promoting appropriate technology for household use. PAHO the Interamerican Development Bank and the Pan American Development Foundation have contributed either chlorinators or calcium hypochlorite to disinfect water supplies in Peru.

Use of wastewater effluent in agriculture

The use of domestic sewage and other liquid wastes for irrigation of food and forage crops has been under scrutiny for almost 100 years but the benefits, risks and costs continue to be evaluated, particularly in arid zones. The physical, chemical, biological and hygienic properties of wastewater vary greatly with method of treatment employed. In this paper the several well known generic methods of wastewater treatment and some less known newer methods are examined in detail with respect to these properties in arid zones. Trade offs in land energy and resources are also subjected to stochastic examination.

Reuse of tertiary municipal wastewater effluent for irrigation of raw-eaten food crops: A five year field study

Reuse of tertiary municipal wastewater effluent for irrigation of raw-eaten food crops: A five year field study

Reuse of tertiary municipal wastewater effluent for irrigation of raw-eaten food crops: A five year field study

Reuse of tertiary municipal wastewater effluent for irrigation of raw-eaten food crops: A five year field study

Rural energy technology assessment: A Sri Lankan case study

This paper reports and assesses the results of a comparative survey on the costs and benefits of windmills and kerosene pumpsets for irrigation of subsidiary food crops in the Dry Zone of Sri Lanka. Secondary objectives are to draw out lessons from the survey (i) for other renewable energy technology programs and (ii) for evaluation methods. Survey results provide a windmill user evaluation, a cost analysis and a comparison of net crop income under the two techniques (windmill and kerosene pumpset). At both financial and economic prices the renewable energy technology is found inferior to the fossil-fuel based technology. The small data set requires caution in drawing final conclusions but does suggest that there is a critical loss in flexibility over cropping patterns by adoption of the windmill.

Health and safety aspects of irrigation of raw-eaten food crops with reused water

The Monterey Wastewater Reclamation Study for Agriculture (MWRSA) has Completed its first year of a five-year pilot effort to investigate and to demonstrate feasibility of food crop irrigation with reclaimed municipal effluent. The project comprises a 96-plot field trial for statistical comparison of three water treatments: an eight-hectare commercial scale farm for demonstration of water reclamation for growing lettuce, broccoli, cauliflower, celery, and artichokes; an aerosol study, a virus assay, market studies, and other ancillary investigations. First year results preliminarily indicate that the main hypothesis of the study will prove to be true, i.e. “raw-eaten food crops irrigated with properly treated municipal wastewater effluent are safe for human consumption”.