Jorge Tarchitzky

Effects of treated wastewater irrigation on the dissolved and soil organic carbon in Israeli soils.

In many arid and semi-arid regions, the demand for drinking water and other domestic uses is constantly growing due to demographic growth and increasing standard of living. Therefore, less freshwater is available for agricultural irrigation and new water sources are needed. Treated wastewater (TWW) already serves as an important water source in Israel since more than 40 years and its usage will further be extended. Related to its high loads with nutrients, salts and organic materials its use as irrigation water can have major effects on the soil physical, chemical and biological properties, in the worst case leading to soil degradation. Additional organic matter reaches the soil with the effluent water and soil microbial activity is stimulated. Soil organic carbon (SOC) seems to accumulate in the topsoil and tends to decrease after long-term irrigation with secondary TWW in the subsoil. The amount of dissolved organic carbon increased and the aromaticity of the organic compounds in the soil percolates decreased over the irrigation period. Priming effects, occurring after stimulation of microbial activity by the addition of easily degradable substances, could be found in the soils and were stronger for subsoil (1 m depth).

Properties and distribution of humic substances and inorganic structure-stabilizing components in particle-size fractions of cultivated Mediterranean soils.

Aggregate-size fractions of two cultivated calcareous Mediterranean soils (Mevo Horon and Palmahim) were characterized with regard to organic matter and other soil components involved in soil structure stabilizing reactions. The parameters determined in each aggregate-size fraction included: particle size distribution and contents of CaCO 3 , organic C and N, fulvic acid fraction (FF), humic acid (HA), total humic substances (HS), and extractable Al and Fe. Except for the organic C and HS in the Mevo Horon (MH) soil, all of the calculated ratios between the contents of each of the components in any size fraction and that calculated for the same component in the 250 μm) and the smallest (<2 μm) aggregate-size fractions. Higher polysaccharide content was observed in the larger particle size fraction, reflecting the influence of recent plant material.

Potential drawbacks associated with agricultural irrigation with treated wastewaters from desalinated water origin and possible remedies

Over 90% of the water supplied in the coastal region in Israel in 2013 (600 Mm(3) y(-1)) will be from desalination plants. The wastewater generated from this water (>400 Mm(3) y(-1)) is planned, after proper treatment, to be reused for agricultural irrigation, making this low-salinity water the main agricultural-sector future water source. In this respect both the Mg(2 + ) concentration and the Sodium Adsorption Ratio value of the water are of concern. We show that the typical Na(+) concentration addition to wastewater (between approximately 100 and approximately 165 mg L(-1)) is much higher than the combined addition of Ca(2 + ) and Mg(2 + ) (between 0 and several mg L(-1)). Since desalinated water is typically supplied with low Ca(2 + ) and Mg(2 + ) concentrations ( approximately 35 and 0 mg L(-1) respectively), the treated wastewater is characterized by very low Mg(2 + ) concentrations, low salinity and very high SAR values, typically >6 and up to 10 (meq L(-1))(0.5). SAR values can be lowered by adding either Ca(2 + ) or Mg(2 + ) to desalinated water. Adding Mg(2 + ) is preferable from both health (minimizing cardiovascular disease hazards) and agriculture (inexpensive Mg fertilization) aspects. The low cost of Mg(2 + ) addition at the post-treatment stage of desalination plants corroborates the request for Mg(2 + ) addition in regions where treated wastewater from desalinated water origin is planned to be reused for irrigation.

Induction of soil water repellency following irrigation with treated wastewater: effects of irrigation water quality and soil texture

We hypothesized that organic matter (OM) content originating from treated wastewater (TWW) irrigation and soil texture dominate the intensity of soil water repellency. The relationship between soil texture, wastewater treatment level, and water repellency was examined in a 3-year lysimeter experiment (2008–2010). Soil type–water quality combinations, consisting of three soils with different specific surface area (SSA) and four levels of water quality differing in OM content, were tested. In each year, water repellency developed in all TWW quality treatments, but not in freshwater-irrigated controls. At the end of each year (except 2009), the highest degree of repellency was exhibited by sandy soil treated with the lowest quality TWW (highest OM content). The lowest degree of water repellency was consistently exhibited by the soil with the highest SSA irrigated with the highest quality TWW (lowest OM content). Water quality, rather than SSA, was the dominant factor in determining degree of repellency induced by TWW irrigation.

Biological and chemical fouling in drip irrigation systems utilizing treated wastewater

A major constraint on the use of treated wastewater (TWW) in microirrigation systems is the potential for fouling. This research aimed to assess the occurrence of fouling in drip irrigation systems applying TWW and determine the quantity and chemical characteristics of the fouling. A field survey was performed to determine the incidence of chemical and biological fouling in irrigation systems and its influence on system performance. Dripper flow rate, total and volatile solids, chemical composition, and diffuse reflection infrared Fourier transform (DRIFT) spectra of the fouling material were determined. Fouling was found in all of the drip irrigation systems sampled under a variety of conditions. The fouling contained a high percentage of organic matter (OM), except for two instances where the material was mainly inorganic. Identification of the functional groups using DRIFT showed that the OM found is essentially of aliphatic and amide origin. Comparing the spectra obtained from the various sites revealed considerable similarity in the material properties. This suggests a common mechanism in all irrigation systems tested, but a different accumulation rate. A high correlation was found between total phosphorus concentration, the sum of Ca and Mg concentrations and the TWW pH, and the content of total and organic carbon in the fouling. In addition, the correlation between equipment age and the amount of accumulated total solids was high for systems containing high quantities of fouling. The concentration of volatile solids was highly correlated with the age of the irrigation system.

Water quality and daily temperature cycle affect biofilm formation in drip irrigation devices revealed by optical coherence tomography

Abstract Drip irrigation is a water-saving technology. To date, little is known about how biofilm forms in drippers of irrigation systems. In this study, the internal dripper geometry was recreated in 3-D printed microfluidic devices (MFDs). To mimic the temperature conditions in (semi-) arid areas, experiments were conducted in a temperature controlled box between 20 and 50°C. MFDs were either fed with two different treated wastewater (TWW) or synthetic wastewater. Biofilm formation was monitored non-invasively and in situ by optical coherence tomography (OCT). 3-D OCT datasets reveal the major fouling position and illustrate that biofilm development was influenced by fluid dynamics. Biofilm volumetric coverage of the labyrinth up to 60% did not reduce the discharge rate, whereas a further increase to 80% reduced the discharge rate by 50%. Moreover, the biofilm formation rate was significantly inhibited in daily temperature cycle independent of the cultivation medium used.

The Use of Treated Wastewater for Irrigation as a Component of Integrated Water Resources Management: Reducing Environmental Implications on Soil and Groundwater by Evaluating Site-Specific Soil Sensitivities

The use of non-conventional water resources like treated wastewater (TWW) is a contribution to alleviate the pressure on available natural water resources in water scarce regions, as it allows higher quality water to be available for other purposes. Population growth, improved living standards and expected climate change impacts will raise the importance of water reuse progressively. TWW can be utilized for various purposes, such as for irrigation, conservation, groundwater recharge or domestic and industrial use. In the eastern Mediterranean region, irrigation with water of marginal quality has a long history, with Israel being the promoting pioneer in advanced treated wastewater use policy and technology. However, apart from health and crop quality concerns, there are potential adverse effects of TWW application on soil and groundwater quality to be considered. In aiming to avoid unsustainable exposures, the regional risks related with TWW irrigation have to be specified and differentiated according to regional soil properties. Within the multinational joint research project network GLOWA (Global Change and the Hydrological Cycle) Jordan River, a regional based land evaluation was conducted for the area of Israel, Jordan and the Palestinian Authority by combining supraregional spatial soil data using a geographic information system (GIS). These data were used to identify land more or less sensitive towards TWW irrigation and for the implementation in regional decision support systems (DSS) related to water allocation and the extension of irrigation infrastructure.

Water Repellency Induced by Organic Matter (OM) in Treated Wastewater (TWW) Infiltration Ponds and Irrigation

Treated wastewater (TWW) irrigation is being largely applied to soils in semiarid and arid regions around the world that are subjected to a shortage of freshwater (FW) resources. This research dealt with effects of TWW irrigation on water infiltration, retention and distribution in soils. Long-term TWW irrigation was found to alter physico-chemical properties of soils due to accumulation of organic matter (OM) originating from the applied TWW and may result to soil water repellency (SWR). This research dealt with two aspects of the problem: (1) SWR in TWW-irrigated soils and (2) SWR in infiltration basins (tertiary treatment) of wastewater. Significant SWR was found in these two systems involving utilization of TWW.

Soil surface water repellency induced by treated wastewater irrigation: physico-chemical characterization and quantification

Irrigation with treated wastewater (TWW) is commonly practiced in Israel to relieve freshwater (FW) shortages. We hypothesized that the organic matter (OM) originating from TWW irrigation alters the physico-chemical properties of the soil, induces water repellency in the soil’s top layer, and consequently alters water distribution in the soil profile. In measurements taken in an avocado orchard on a clayey soil, water repellency was found in TWW-irrigated plots. In addition, smaller wetted surface areas were recorded around the drippers in comparison with FW drippers. Drier zone below soil surface was observed in TWW-emitting drippers. OM extraction from the different plots exhibited differences in quantity and quality of organic substances between TWW- and FW-irrigated soils, with a higher quantity of hydrophobic substances in the TWW-irrigated soil extract.

Composted biosolids and treated wastewater as sources of pharmaceuticals and personal care products for plant uptake: A case study with carbamazepine

Irrigation with treated wastewater (TWW) and application of biosolids to arable land expose the agro-environment to pharmaceuticals and personal care products (PPCPs) which can be taken up by crops. In this project, we studied the effect of a carrier medium (e.g., biosolids and TWW) on plant (tomato, wheat and lettuce) uptake, translocation and metabolism of carbamazepine as a model for non-ionic PPCPs. Plant uptake and bioconcentration factors were significantly lower in soils amended with biosolids compared to soils irrigated with TWW. In soils amended with biosolids and irrigated with TWW, the bioavailability of carbamazepine for plant uptake was moderately decreased as compared to plants grown in soils irrigated with TWW alone. While TWW acts as a continuous source of PPCPs, biosolids act both as a source and a sink for these compounds. Moreover, it appears that decomposition of the biosolids in the soil after amendment enhances their adsorptive properties, which in turn reduces the bioavailability of PPCPs in the soil environment. In-plant metabolism of carbamazepine was found to be independent of environmental factors, such as soil type, carrier medium, and absolute amount implemented to the soil, but was controlled by the total amount taken up by the plant.