Nava Haruvy

Agricultural reuse of wastewater: nation-wide cost-benefit analysis

Abstract The increasing agricultural reuse of treated effluent serves goals such as promoting sustainable agriculture, preserving scarce water resources, and maintaining environmental quality. Also, irrigating with wastewater may reduce purification levels and fertilization costs, because soil and crops serve as bio-filters, and wastewater contain nutrients. Policy decisions regarding the level of purification and location of agriculture using wastewater, should consider multifarious aspects including costs, hazards and benefits of agricultural reuse of wastewater. The present paper demonstrates, in a simple way, how to tackle decision-making questions regarding the disposal of wastewater from an economic standpoint. It compares various wastewater reclamation and reuse options such as treatment levels and location of reuse, by computing the net national benefit as applied to a specific case study in central Israel. Several alternatives were compared including river disposal, local agricultural reuse of wastewater, and conveyance to the south. Estimated costs include those of treatment, storage and conveyance, while benefits comprise the value of agricultural output, the decrease in fertilization costs, and aquifer recharge. Hazard costs estimated in this analysis relate to seepage of nitrogen and health risks. According to this analysis, wastewater irrigation in the center of Israel saves US

Agricultural practices, soil fertility management modes and resultant nitrogen leaching rates under semi-arid conditions

0.50–0.60/m3 compared with river disposal, and US

Wastewater reuse—regional and economic considerations

0.10–0.20/m3 compared with conveyance to the south. Conveyance to the south of tertiary-treated effluent (as in the Dan Region Treatment Plant) instead of discard saves US

Cost assessment of various means of averting environmental damage and groundwater contamination from nitrate seepage

0.12/m3, justifying a subsidy.

A model for integrated water resources management in water-scarce regions: irrigation with wastewater combined with desalination processes

Abstract Under semi-arid or arid conditions, growing needs for agricultural commodities dictate the intensification of agricultural activities through the application of irrigation and fertilization practices aimed at increasing crop yields. A certain amount of the added irrigation water is designed to seep below the root zone and leach excessive salts accumulated in the irrigated soil. This entails, in part, recharging the ground water-table aquifers. Hence, intensification of agricultural activities introduces a long-term risk of groundwater pollution by unused fertilizers, e.g., nitrogen, salts and pesticides, herbicides, leached from the irrigated fields. To avert or minimize this risk, the amounts of applied water and fertilizer should be determined and minimized by optimizing them to match crop requirements. The objectives of the present work were to determine the amounts of water and salts leached below several agricultural areas subjected to differing soil fertility practices, and to try to relate them to the yields obtained. Published data and experimental data sets of water, chloride and nitrate concentration – depth distributions were used and analyzed. The results show that intensification of agricultural activities leads to increased hazards to surface and groundwater pollution and this can be diminished provided balanced irrigation – fertilization programs are developed for different crops, by using the results of leachate loads seeping from long-term fertility and irrigation studies (permanent plot experiments).

Reuse of Wastewater in Agriculture- Economic Assessment of Treatment and Supply Alternatives as Affecting Aquifer Pollution

Wastewater treatment and disposal has become a major component of policy-making subject, because of growing awareness of environmental quality issues. Agricultural use of treated effluents helps to maintain environmental quality, and simultaneously furthers other national goals such as providing sustainable agriculture while preserving scarce water sources. Another advantage of irrigation with wastewater is the possibility of decreasing the purification level and the derived treatment costs, thanks to the role of soil and crops in acting as a bio-filter. Also, using the nutrients available in wastewater may diminish fertilization costs. The considerations for policy decision making include many factors such as the level of purlfication, the location of agriculture and the types of crops. The regional dimension is reflected in the way the decision on where to convey the wastewater influences the choice of agricultural crops, the fate of aquifers and the related costs. For example, in Israel, wastewater treated in the center of the country may pollute the coastal aquifer, whereas conveying this wastewater to the south, where there is no active aquifer gives rise to increased conveyance costs and loss of agriculture in the center. In this paper a general methodology for environmental policy decision making in relation to wastewater is developed and applied in an Israeli case study.

Irrigation with Treated Wastewater in Israel-Assessment of Environmental Aspects

Abstract Fertilizers are used in addition to irrigation water to increase soil fertility and productivity, but cropped areas are sources of groundwater contamination due to loads of nitrates carried downwards by seepage of excess water. The public is increasingly aware of the grave problems of environmental damage caused by groundwater pollution. These environmental effects are not considered by farmers, whose production motivation is to get high profits, and there is a clash of interests between the farmers and the state. Consideration of environmental issues can be imposed on farmers by constraints on resources or by pricing of inputs. We compare the interests involved and assess the possibilities open to both the individual and the state. Hence, we quantify the agricultural inputs required and suggest appropriate administrative and pricing methods to control resultant damages. These are estimated by means of a linear-programming based-optimization model applied to the southern region of Israel.

Risk management of transboundary water resources: sustainable water management of the River Jordan basin area

We have developed a model for planning water supply from diverse sources, including groundwater, the National Water Carrier, wastewater and seawater. The model integrates hydrological, technological and economic considerations, and estimates the economic and environmental impacts of alternative water management policies; it was implemented in a case study of the Emek Heffer and northern Sharon regions in Israel. A unique hydrological database was constructed and a hydrological model was developed for planning water resources use and forecasting the chloride concentration in the aquifer. The costs of desalination processes and of the water supply to the region under various scenarios were estimated. The results include recommendations for the water treatment level and for desalination of different water sources, and forecasts of the implementation costs. We conclude that the economic cost of improving the quality of the supplied water and of the aquifer water should be considered in decision making.

Integrating technology foresight methods with environmental life cycle assessment to promote sustainable agriculture

Treated wastewater in Israel is the unlimited and a reasonable alternative for water supply to agriculture as the high-quality fresh water supply is gradually transferred to urban uses. Still, the domestic and industrial effluents carry pollutants including micro and macro organic and inorganic matter which potentially pose hazards to health, the environment, crops and soils, and may deteriorate aquifer quality. Nevertheless, for irrigation in Israel, using treated wastewater is the best means to facilitate agricultural production under conditions of water scarcity, since it uses a water resource that is available in large quantities and that already requires treatment, in order to prevent environmental damage. Salinity level is higher in effluents than in influents, while regular treatment processes do not get rid of salinity, unless combining relatively expensive desalination processes.

Risk Assessment of The Effect of Wastewater Treatment and Desalination Processes on the Coastal Aquifer in Israel

Population growth increases the output of sewage, which must be treated and discarded. Agricultural reuse can function as wastewater disposal, and simultaneously convert an environmental threat to a benefit, i.e., the supply of irrigation water to agriculture. Both quantity and quality aspects should be considered when irrigating with treated effluents, since its constituents may affect crops and groundwater. In this paper we refer to nutrients, represented by nitrogen or nitrates (NO3), and salinity, represented by EC (electrical conductivity) or chlorides (Cl). The levels of these constituents in wastewater are usually elevated; therefore, they may affect crops, soil structure, or groundwater quality. Combining wastewater treatment and desalination processes to maintain groundwater quality can diminish these impacts and prevent environmental deterioration. We have assessed the environmental impacts of wastewater irrigation by focusing on nitrate and chloride constituents. To that end, we developed an economic-hydrological model that incorporates various watersources and treatment processes in order to analyze the accelerated contamination of groundwater.