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Plastic processes and products are constantly growing. About two million tons of plastic were produced in 1950. In 2015, about 380 million tons of plastic were manufactured, of which only around four million tons were sent for recycling during the same year. Plastic pollution has become a global problem. Plastic products and waste cause an environmental hazard that disfigures the natural landscape, damaging aquatic ecology, adversely impacting marine habitat, soils, air, causing groundwater contamination, and increasing greenhouse gas emissions. The three dimensions (3D) printing process is utilizing a computer-aided design (CAD) model, usually by successively adding material in layers. Fused deposition modeling (FDM) – frequently called filament freeform fabrication, is a 3D printing process that uses thermoplastic material as a continuous filament. The goal of the work is to build a prototype printer that uses disposed plastic bottles as a source for raw material. The idea for current work stems from the need to save resources and simultaneously protect the environment. A 3D home printer was created for this purpose however, changes and adjustments were made to implement the idea of the project. A plastic bottle cutter was built in order to insert the raw material into the prototype printer. In addition, the framework of the extruder was substituted and a nozzle diameter was installed. Additional adjustments were made in the printer to maintain a continuous and uniform flow of the hot plastic that was poured onto the printer surface during the printing process.

Biofouling in anaerobic membrane bioreactors (AnMBRs) has not been studied widely. Moreover, the effect of membrane surface properties on biofilm formation beyond initial deposition is controversial. We investigated biofouling with polyvinyldifluoride, polyacrylonitrile, and zwitterion-modified polyethersulfone ultrafiltration membranes having different properties during 72 h filtration using natural anaerobes isolated from AnMBR and analyzed biofilm characteristics by physicochemical and molecular techniques. A decrease in membrane performance was positively correlated with biofilm formation on polyvinyldifluoride and polyacrylonitrile membranes, and as expected, physical cleaning effectively mitigated biofilm on hydrophilic and low-roughness membranes. Surprisingly, while the biofilm on the hydrophilic and low-surface roughness zwitterion-modified membrane was significantly impaired, the impact on transmembrane pressure was the highest. This was ascribed to the formation of a soft compressible thin biofilm with high hydraulic resistance, and internal clogging and pore blocking due to high pore-size distribution. Anaerobe community analysis demonstrated some selection between the bulk and biofilm anaerobes and differences in the relative abundance of the dominant anaerobes among the membranes. However, correlation analyses revealed that all membrane properties studied affected microbial communities' composition, highlighting the system's complexity. Overall, our findings indicate that the membrane properties can affect biofilm formation and the anaerobic microbial population but not necessarily alleviate biofouling.

One of the main challenges in the realization of anaerobic membrane bioreactors (AnMBRs) for wastewater treatment is reducing membrane fouling. Although AnMBRs employ various types of membranes, the relationship between the surface properties of the membrane and the fouling dynamics of the AnMBR is unclear. To characterize this relationship, we studied the fouling of three types of morphologically comparable membranes with different physicochemical surface properties, which were installed simultaneously in a submerged AnMBR (SAnMBR) treating domestic wastewater, under a sub-critical flux and for various filtration durations (up to 30 days). For each membrane type, we characterized both the fouling rate and the foulant composition. We found that, during the first few days of operation, the fouling rate, which was low, and the foulants composition were similar for all three membranes. The fouling rate and fouling composition for the membrane with the high and positive surface free energy (i.e., hydrophilic) remained stable throughout the experiment, whereas, after a few days the two membranes that were characterized as hydrophobic (based on the low and negative surface free energy) experienced a sudden increase in the fouling rates and the foulant composition changed and resembled that of the mixed liquor in the SAnMBR. Statistical analysis clearly indicated that the surface free energy is the dominant parameter that controls fouling rates as well as the dynamic between the EPS components in the fouling layer. These results distinctly show that membranes with certain properties can affect fouling accumulation during filtration and physical cleaning efficiency to maintain low fouling, even in the complex environment of a SAnMBR. Higher flux recovery of the hydrophilic membrane measured after static (no flux) experiments and the fouling dynamic during batch filtration experiments support these findings. It can be concluded that the combination of physical cleaning and operating under sub-critical flux together with the optimization of the membranes properties can effectively control the fouling degree in SAnMBR. This, in turn, can lower the energy consumption for fouling control and thus promote the application of AnMBR for wastewater treatment. Further research on the effect of the membrane properties on the foulants composition, biofouling, and cleaning approaches is needed.

Membrane biofouling constitutes a great challenge in anaerobic membrane bioreactor (AnMBR). Here, we studied the initial deposition of anaerobes, the first step in biofilm formation, with a consortium isolated from an AnMBR on membranes with different surface properties and under two shear rate conditions without filtration. We found that the cell transfer coefficient, calculated from the initial deposition experiments, was similar under the two shear rates for the hydrophobic membranes, but much higher under low shear rate and much lower under high shear rate, for the hydrophilic membrane. The cell transfer coefficient measured under filtration mode and at a higher shear rate showed a similar trend. The pioneer bacteria and archaea (without filtration) were identified by next-generation sequencing. The results showed that the selective force for the dissimilarity of the pioneer bacterial and archaeal diversity was the shear rate and the membrane surface properties, respectively. However, statistical analyses revealed minor changes in the pioneer bacteria (class level) and archaea (order level) populations under the various conditions. These results shed light on the first step of biofilm formation on the membranes in AnMBRs and emphasize the importance of hydrodynamic shear and membrane surface properties on the initially deposited anaerobes.

Fouling remains one of the main issues related to membrane filtration during seawater desalination. The main acceptable methods are based on adding chemical reagents to the low quality waters that are going to be desalinated and/or adjusted to the membrane materials and the waters. This becomes a real issue when developing desalination plants for small communities, located along the sea shore. The approach adapted here is based on Coastal Soil Seawater Pumping (CSSP), with a pretreatment stage for the desalinated water. A management model was used for construction of main lines characterizing the system. In this work, a management model for small and relatively isolated communities is presented. It allows the water authorities of urban areas located close to the sea to provide desalinated water for the benefit of their residents, primarily for drinking purposes. Water from local wells that contain relatively high nitrate (NO3−) levels will be blended with the desalinated waters that are produced and distributed along the seashore to reach acceptable levels of 50–70 mg/L nitrates this will replace the “killed” wells and revive wells with high nitrate contents.

Nanotechnology applications can be used for filtering low quality waters, allowing under given conditions, the removal of salts and other micropollutants from these waters. A long-term field experiment, implementing nanotechnology in the form of UltraFiltration (UF) and Reverse Osmosis (RO) for salt removal from treated wastewater, was conducted with secondary effluents, aiming to prove the sustainability of agricultural production using irrigation with treated wastewater. Six outdoor field treatments, each under four replications, were conducted for examining the salt accumulation effects on the soil and the crops. The field experiments proved that crop development is correlated with the water quality as achieved from the wastewater filtration capability of the hybrid nanotechnology system. The key goal was to maintain sustainable food production, despite the low quality of the waters. Of the six treatment methods tested, irrigation with RO-treated effluent produced the best results in terms of its effect on soil salinity and crop yield. Nevertheless, it must be kept in mind that this process is not only costly, but it also removes all organic matter content from the irrigation water, requiring the addition of fertilizers to the effluent.

Reverse Osmosis (RO) is one of the most efficient methods for salt removal from seawater, saline water and from wastewater. However, efficient application of RO for such purposes is still hindered by several operational drawbacks, the main one being membrane fouling. Herein, field experiments were conducted on a commercial scale membrane system treating domestic wastewater for agriculture irrigation. It was conducted for developing and verifying of a simple and practical tool for evaluating RO membrane fouling. The membrane system consisted of an UltraFiltration (UF) stage and a complementary RO one. The UF component is applied for the removal of the organic matter and pathogenic bacteria while the RO is used for the dissolved solids removal from the wastewater, bringing the water to drinking quality. In our field experiments the membrane system capacity was around 125 m 3 /day and it was run smoothly for a continuous period of four years, providing unrestricted quality effluent that was used for irrigation of a series of seasonal commercial field crops. Following analysis of both field and theoretical data, it was found that back flushing with clean water without adding extra chemicals can be applied in order to minimize fouling of the RO component. Back flushing has two major benefits: saving expenses for the chemicals utilization and improved environmental control.

The research compares four types of different designs of membrane bioreactors: (1) with 295-mm draft tube and without plastic carriers; (2) plastic carriers and 295-mm draft tube; (3) plastic carriers and 235-mm draft tube with two meshes around the bottom and top of a draft tube; and (4) plastic carriers without a draft tube. The feed for the reactors was artificial wastewater made from domestic wastewater and chicken manure, and membrane test data were based on a hollow fiber membrane module under ambient desert conditions. Process operation type D is the optimal choice. Mathematical analysis using total ranking methods, multi-indicator decision-making, and Hasse diagram support this choice. Concerning analysis by the different tools, inconsistencies between the rankings are noticed. Partial order ranking, as a method without any pre-assumptions concerning the possible relation between the single parameters, proves to be an elegant ranking method.

The aim of this study was to test the local small-scale treatment of grey water (mainly shower water) of a sports centre to be reused for recreational irrigation. Due to the low organic load which limits the growth and aggregation of biomass, a membrane bioreactor (MBR) was selected for this purpose. A pilot-scale system was operated and studied for more than 1 year in the conduct of this task. The MBR process proved to be a very efficient biological treatment stage, producing superior effluents with low BOD5, NH4 + and TSS. Detergents and COD were degraded efficiently and the effluents did not contain total coliforms and faecal coliforms. Due to the low organic load, biomass accumulation was very slow and the system could reach and function at relatively low mixed liquid suspended solid (MLSS) levels. The MBR ultrafiltration module thus was able to produce a steady permeate flux for more than 1 year just with air scouring and without membrane backwash or chemical regenerating. Another important advantage was the minimal requirement for excess sludge wastage.

A model examining the National Water Wealth (NWW) and its allocation between the municipal sector and the agricultural sector, where water value is defined as the present value of Water Rights, is presented. Five factors are considered: (i) uncertainty of water supply; (ii) population growth rate; (iii) the effect of time on NWW without new water production; (iv) agency costs, and; (v) production of new waters. The work is based on the model by Jensen and Meckling (J Finance Econ. 3:305–360, 1976), dealing with the effects of agency costs on the value of public companies. Agency costs are subject to conflicting interests between managers, shareholders and bondholders. In the water economy agency, costs stem from a divergence of interests between the government, the agricultural and the municipal sectors. Uncertainty of supply reduces water wealth of both sectors, with a stronger adverse impact on water wealth of the agricultural sector. Our model shows how production of new waters can have contributive effects on national water wealth. The modeling demonstrates the option of reducing the overall uncertainty of water supply and production of new waters which leads to favorable effects on the national water wealth.

Water shortage around the world enhanced the search for alternative sources. Greywater (GW) can serve as a solution for water demands especially in arid and semi-arid zones. However, issues considered which include acceptability of GW segregation as a separate water treated stream, allowing its use onsite. Consequently, it is the one of next forthcoming water resources that will be used, primarily in the growing mega-cities. It will be even more rentable when combined with the roof runoff water harvesting and condensing water from air-conditioning systems. Reuse of GW is as well beneficial in the mega-cities subject to the high expenses associated with wastewater and fresh water conveyance in the opposite direction. The main problem associated with GW reuse is the quality of the water and the targeted reuse options. At least two main options can be identified: the public sector that is ready to reuse the GW and the private sector which raises extra issues related to the reuse risks. These risk stems from the on yard use of GW, relatively close to the household location. The main focus of the Israeli guidelines for GW use is on the private and single house. The problem is less rigorous in public facilities, where the amounts are relatively large and the raw GW is relatively diluted. The two main principles adopted for reuse are: (i) greywater can be minimally treated since it differs from the black wastes, and; (ii) no contact exists with the resident around. The aggravated standards are an indication of the sensitivity issues related to the problem.

The high demands for desalination of seawater in the past few years have forced manufacturers to evaluate new potential technologies for boron removal. This work examines the production options by the analytic hierarchy process (AHP) model. According to the AHP model and the Hasse diagram technique, derived from the theory of partially ordered sets, the permeate split and the use of ion-exchange in series is an open new area for a new expertise.

This study investigates the oxidation of municipal wastewater (WW) by complexation with natural polyphenols having radical scavenging activity, such as (3,4,5 tri-hydroxy-benzoic acid) gallic acid (GA) in alkaline pH (>7), under ambient O2 and temperature. Physicochemical and structural characteristics of GA-WW complex-forming are evaluated by UV/Vis spectroscopy. The comparative analysis among UV/Vis spectra of GA monomer, GA-GA polymer, WW compounds, and GA-WW complex reveals significant differences within 350-450 and 500-900 nm. According to attenuated total reflectance (ATR) spectroscopy and thermogravimetric analysis (TGA), these spectra differences correspond to distinct complexes formed. This study suggests a novel role of natural polyphenols on the degradation and humification of wastes.

Improving biomass properties is a practical approach towards minimizing fouling in membrane bioreactors (MBRs). A possible and promising direction for reaching such purposes is the use of a hybrid growth MBR (HG-MBR) which combines activated sludge and biofilm processes. Four types of MBR of different design principles were examined in the present study: (i) an airlift MBR (A-MBR) equipped with a draft tube but without carriers (as a control); (ii) an HG-MBR containing carries but without a draft tube; (iii) an airlift HG-MBR (AHG-MBR) equipped with a draft tube and carriers, and; (iv) a fixed-bed HG-MBR (FHG-MBR) equipped with a draft tube and carriers, including two meshes around the bottom and top of the draft tube. For each of these configurations, a mixed wastewater consisting of domestic wastewater and chicken manure was treated, using a hollow fiber UF membrane module of ZW-10 under ambient desert conditions. The results demonstrate that generating adequate balance between MLSS and biofilm fractions is important in order to achieve high removal efficiency and low fouling tendency in an HG-MBR. The use of AHG-MBR and FHG-MBR has some limitations. Operation of the HG-MBR under appropriate aeration conditions which allows maintaining carriers’ recirculation and is advantageous.

Membrane fouling is one of the main constraints of the wide use of membrane bioreactor (MBR) technology. The biomass in MBR systems includes extracellular polymeric substances (EPS), metabolic products of active microbial secretion that adversely affect the membrane performance. Solids retention time (SRT) in the MBR is one of the most important parameters affecting membrane fouling in MBR systems, where fouling is minimized at optimal SRT. Among the operating parameters in MBR systems, SRT is known to strongly influence the ratio of proteins to polysaccharides in the EPS matrix. In this study, we have direct evidence for changes in EPS adherence and viscoelastic properties due to changes in the sludge removal rate that strongly correlate with the membrane fouling rate and EPS composition. EPS were extracted from a UF membrane in a hybrid growth MBR operated at sludge removal rates of 59, 35.4, 17.7, and 5.9 L day-1 (corresponding SRT of 3, 5, 10, and 30 days, respectively). The EPS adherence and adsorption kinetics were carried out in a quartz crystal microbalance with dissipation monitoring (QCM-D) technology in several adsorption measurements to a gold sensor coated with Polyvinylidene Fluoride (PVDF). EPS adsorption to the sensor surface is characterized by a decrease of the oscillation frequency and an increase in the dissipation energy of the sensor during parallel flow of aqueous media, supplemented with EPS, above the sensor surface. The results from these experiments were further modeled using the Voigt based model, in which the thickness, shear modulus, and shear viscosity values of the adsorbed EPS layers on the PVDF crystal were calculated. The observations in the QCM-D suggested that the elevated fouling of the UF membrane is due to higher adherence of the EPS as well as reduction in viscosity and elasticity of the EPS adsorbed layer and elevation of the EPS fluidity. These results corroborate with confocal laser scanning microscopy (CLSM) image analysis showing thicker EPS in close proximity to the membrane surface operated at reactor conditions which induced more fouling at elevated sludge removal rates.

Seawater desalination is a rising technology intended to overcome water scarcity and is increasingly being used for the production of drinking water. A good quality pretreatment process is prominent to the successful operation of a Seawater Reverse Osmosis (SWRO) plant. The tasks of the intake and the pretreatment modules are to prevent fouling and to extend the lifetime of the reverse osmosis membranes. To practice the method of assessment design, 19 seawater plants with 11 different design strategies have been evaluated. The assessed strategies consist of: (i) Intake treatment, (ii) pretreatment aid (coagulation, flocculation, clarification), and (iii) pretreatment unit. Every possible combination of the design elements has been evaluated by a set of 15 attributes. The comparative evaluation has been conducted by Hasse diagram technique (HDT) using PyHasse software. The result of the HDT application includes 7 favorable incomparable design strategies. In order to solve the incomparability, the Condorcet–Kemeny–Young–Levenglick (C–K–Y–L) ranking procedure was additionally used and rendered the optimal design that is based on subsurface intake and membrane (ultrafiltration) pretreatment facilities. According to the results, both mathematical methods, i.e., the HDT in combination with the C–K–Y–L, procedure can be powerful and helpful tools to assist decisions concerning design strategies.

Both conformation and adsorption characteristics of extracellular polymeric substances (EPS) are affected by water chemistry in general and by the pH in particular. Therefore, changes in pH during operation of membrane bioreactor (MBR) systems are likely to affect fouling of ultrafiltration (UF) membranes. Pore clogging of UF membranes attributed to EPS can be affected by the pH in a complex manner: since the heterogeneous nature of the EPS mixture consists of both aromatic and aliphatic components with carboxylic acids (COOH) and phenolic alcohols (OH), at lower pH, adsorption of EPS to negatively charges surfaces is usually increasing. However, EPS conformation is also affected by pH changes that induce either linear (stretched) or coiled (compact) structure at high and low pH values, respectively. This study shows an increased adsorption of MBR originated EPS to Polyvinylidene Fluoride (PVDF) surfaces at lower pH, probably due to smaller deprotonated chemical functional groups that are in charge of repulsive electrostatic interactions. In contrast to the EPS adsorption results, the fouling rate of UF membrane by similar EPS at pH value of 6.3 was significantly lower than the fouling rate at higher pH value of 8.3. The relation between pH elevation and flux decline during EPS fouling experiment is shown to be a result of EPS conformation and swelling characteristics, which affect water and EPS permeation through the UF membrane pores. When EPS structure is stretched, linear chains are more accessible to the membrane pores that eventually clog the UF membrane at higher pH values.

This paper presents an efficient solution approach for large-scale, desalination process plant layout problems based on revese osmosis (RO) technology. The final plant layouts (i.e. coordinates and dimensions for each equipment item) are determined from an initial feasible solution followed by an iterative improvement procedure based on computer aided algorithms. The applicability of the solution algorithm is demonstrated through an illustrative example (125,000 m3/d). The computational results indicate that the proposed approach successfully achieves good quality solutions based on the objective function (short response time, and flexibility) for seawater desalination plants with modest computational requirements.

This study examines the prospects for using Hydra viridissima toxicity test 96-h LC 50, served as a model invertebrate, Lactuca sativa L . was applied for seeds toxicity test (120-h IC 50 ) and a model plant for an acute toxicity assessment of heavy metals content in water. The heavy metals used to assess the acute toxicity of the water utilized for agricultural irrigation in arid regions includes cadmium (CdCl 2 .2H 2 O), chromium (K 2 Cr 2 O 7 ), zinc (ZnSO 4 . 7H 2 O), and boron (H 3 BO 3 ). A grading of the substances was conducted, and it was found that the toxicity levels for H. viridissima and L. sativa were , with the least harmful first: B < Cr < Zn < Cd and Zn < B < Cr < Cd, respectively. Results indicate that H. viridissima was a more sensitive indicator of toxicity for all of the evaluated substances. However, L. sativa could also be used successfully to rank toxicants in order of their potential hazards.

Membrane fouling in a hybrid-growth membrane bioreactor (HG-MBR) is a complex process affected by many parameters that include operational and environmental conditions, wastewater characteristics, and membrane properties. In this study, we investigated the role of the solid retention time (SRT) on fouling of an ultrafiltration (UF) membrane in an HG-MBR system. Under constant organic loading rate, a decrease in SRT caused a reduction in both mixed liquor suspended solids and sessile biomass. Even though biomass concentration in the reactor was lower, the fouling rate was accelerated. The highest extracellular polymeric substances (EPS) concentration adsorbed to the membrane was observed at the lowest SRT of 2.7 d as compared to SRT of 10 and 26.7 d. The higher organic loading rate per biomass unit tends to increase production of either EPS or soluble microbial products (SMP) that directly induce fouling.

The viscosity of activated sludge plays a major role on oxygen transfer and mass transport and consequently influences the hydrodynamic regime and the system performance of a membrane bioreactor (MBR). Yield stress is an important concept in rheology related to the mixing and power requirements in a stirred tank. This study examined the rheological characteristics of activated sludge sampled in a pilot airlift MBR system for domestic wastewater treatment under ambient desert conditions, using a rotational rheometer (AR 2000, TA Instruments, USA) equipped with cone-plate geometry. Both static and dynamic yield stresses were observed at the transition point of 25 s−1 of shear rate for an MLSS concentration range of 2.74–10.2 g/L. The static yield stress is a phenomenon that has not yet been evaluated for activated sludge. The mechanisms of the co-existence of both static and dynamic yield stresses and their engineering significance are discussed. In addition, a mathematical model to describe the rheological properties of the sludge is proposed. The relationships between viscosity, MLSS, temperature and shear rate were obtained statistically. The activation energy for the viscosity of the sludge in the airlift sMBR was found to be 9.217 kJ mol−1, and could be the cause of rapid fluctuation of transmembrane pressure with temperature variations.

Current and impending legislation for public health and environmental compliance regarding effluent are becoming very stringent. For unrestricted domestic effluent reuse and environmental friendly disposal, the need for advanced treatment processes has attracted great attention during the last decade. Membrane-based treatment technologies for low quality water have exhibited improved performance as well as a reduction of operating and maintenance expenses. Membrane technology also provides a preferable alternative for wastewater reclamation in small and isolated communities. This study presents a long term study of an airlift membrane bioreactor (MBR) for domestic wastewater treatment using a hollow fibre membrane module of ZW-10 under ambient desert conditions (Kiryat Sde-Boker, Israel). In this system, the crossflow velocity across the membrane surface was induced by a cylindrical draft tube to reduce the membrane fouling. Under optimal operating conditions, the system was stable and efficient without e...

Summary A lumped model known as Tank model for regional groundwater flows is proposed to estimate the groundwater flow system of the Osaka plain aquifer of Japan. The aquifer is divided into Tanks within which the average values of the groundwater levels is assumed to be representative in the Tanks. For each Tank the mass-balance equations expressing the conservation of water are written. The Quasi–Newton optimization technique together with Akaike’s Information Criterion, AIC, are employed in order to overcome the problem of the trade-off between the fit of the observed data to the model response and reliability of the parameter estimation. A stable model is established which is believed to be reliable to simulate the groundwater flow pattern of the Osaka plain aquifer. The results suggest disconnection of some regional aquifers as well as inflow of seawater to the deeper layers in the studied period.

Excess of boron in water poses a problem due to adverse effects on crop production as well as human health and aquatic life. This study examined the influence of biofouling of NF and RO membrane on the performance of the membranes in removing boron from a synthetic wastewater effluent. Accelerated laboratory-scale biofouling experiments were carried out with commercial thin film composite NF and RO membranes under controlled conditions. Permeate flux decline, down to less than 25% of its initial value, and substantial decrease in boron rejection were attributed to extensive biofilm growth on the membranes. For the RO membrane, boron rejections declined by 45 and 34% of the initial values for influent boron concentrations of 5.5 and 1.1 mg B/L, respectively, whereas the corresponding declines in boron rejection for the NF membrane were 44 and 13% of the initial values. These adverse effects of biofilm growth on permeate water flux and boron rejection are attributed to both an increase in hydraulic resistance to permeate flow due to bacterial extracellular polymeric substances (EPS) and a biofilm-enhanced concentration polarization near the membrane surface.

Field experiments were conducted in agricultural fields in which secondary wastewater of the City of Arad (Israel) is reused for irrigation. For sustainable agricultural production and safe groundwater recharge the secondary effluent is further polished by a combined two-stage membrane pilot system. The pilot membrane system consists of two main in row stages: Ultrafiltration (UF) and Reverse Osmosis (RO). The UF stage is efficient in the removal of the pathogens and suspended organic matter while the successive RO stage provides safe removal of the dissolved solids (salinity). Effluents of various qualities were applied for agricultural irrigation along with continuous monitoring of the membrane system performance. Best agricultural yields were obtained when applying effluent having minimal content of dissolved solids (after the RO stage) as compared with secondary effluent without any further treatment and extended storage. In regions with shallow groundwater reduced soil salinity in the upper productive layers, maintained by extra membrane treatment, will guarantee minimal dissolved solids migration to the aquifers and minimize salinisation processes.

Treated domestic secondary effluent is a valuable water source that can be reused for diverse purposes. However, in order to minimize health and environmental risks and to maintain adequate levels of sustainable agriculture production on a long range time scale, advanced treatment is required. Advanced effluent quality maintaining minimal risks can be primarily attained by implementing the membrane technology. Field experiments are in progress for secondary wastewater polishing for unrestricted reuse for sustainable agricultural production. The two stage membrane treatment system for the secondary effluent polishing consists of combining two main stages: ultrafiltration (UF) and reverse osmosis (RO) membrane treatment. The UF stage is efficient in the removal of the organic matter and the pathogens while the RO provides the dissolved solids (salinity) removal. Effluent of various qualities is applied for irrigation along with continuous monitoring of the membrane components performance. The experimental data was obtained in the ongoing pilot studies carried out near the City of Arad (Israel) wastewater treatment system (the pilot plant performs in a feed and bleed operation mode). The results indicate the importance of maintaining high quality effluent for sustainable agriculture production. The management modeling gives an idea of the importance in maintaining adequate UF flushing policy in order to minimize expenses due to fouling.

Boron (B) is often found in polluted and desalinated waters. Despite its potentially environmental damaging effects, efficient treatments are lacking. The duckweed Lemna gibba has been shown to remove toxic elements from water; however, its applicability to B removal is unknown. In this study, L. gibba was examined for its tolerance to B in water and its B removal efficiency. Duckweed plants were grown in outdoor 12-day batch experiments in nutrient solution containing 0.3-10 mg B L(-1). Plant biomass production was not affected by B over the tested concentrations during the 12-day cultivation period. Boron removal and the bioconcentration factor of B in L. gibba were highest at initial B concentrations below 2 mg L(-1), and decreased as the initial B concentration increased. Boron content in the plants at the end of the experiment ranged between 930 and 1900 mg kg(-1) dry weight, and was comparable to that of wetland plants reported to be good B accumulators. Boron removal by L. gibba may therefore be a suitable option for the treatment of water containing B concentrations below 2 mg L(-1).

Various countries in the Mediterranean Basin and other arid and semi-arid regions are confronting water shortage issues. This gap between supply and demand is closely linked with agricultural production, environmental conditions, and climate changes. It is also probably due to reduced amounts of precipitation, decrease in natural groundwater recharge and low availability of natural water sources. Special ventures have to be undertaken in order to supply water at adequate quality for all utilization purposes. These can be accomplished by development of additional water sources that currently are considered marginal. The additional sources include saline ground water, treated wastewater and runoff water and sea water for desalination. The study presents reuse options of wastewater in conjunction with minimizing water supply dependence on other high quality water sources. Domestic secondary effluent is a valuable water source for reclamation, however, extra treatment is required to reuse it for unrestricted purposes. It can be achieved primarily by implementation of the membrane technology, namely ultrafiltration (UF) and reverse osmosis (RO) stages. Field results revealed that membrane technology is essential for sustainable production. However, additional work has to be carried out in order to improve the membrane performance and efficacy.

The high demands for desalination seawater in the past few years have forced manufacturers to evaluate new potential technologies for Boron removal. This chapter examines the production options by the analytical hierarchical process (AHP) model. According to the AHP model and the Hasse diagram technique, derived from the theory of partially ordered sets, the permeate split and the use of ion exchange in series is an open new area for a new expertise.

One of the options to prevent membrane fouling is to implement air lifting that can improve the cake removal from the membrane surface. This study presents the results of tests that were carried out at the Institutes for Desert Research, Kiryat Sde-Boker, Israel, and focused on the influence of hydrodynamic conditions on fouling in a pilot-scale immersed membrane bioreactor (IMBR) using a hollow fiber membrane module of ZW-10 (Zenon Environmental, Canada) under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by one conical and four cylindrical draft-tubes. The relationship between the crossflow velocity and the aeration intensity, the influence of the crossflow on fouling rate under various hydrodynamic conditions were investigated and optimal operating conditions were obtained. Optimal operating conditions were reached during the long-term experiment period (70 days) for the treatment of domestic wastewater. The system was stable without external chemical cleaning. The results showed that the permeate was of high quality, and the removal of COD and BOD was 94.0% and 98.8%, respectively.The crossflow near the membrane surface reveals a major contribution for minimizing membrane fouling, and could offer guidelines for future design of similar systems.

Field experiments are in progress for secondary wastewater upgrading for unrestricted use for irrigation and sustainable agricultural production. The integrative treatment system for the secondary effluent polishing is based on implementing in series of two main treatment stages: ultrafiltration (UF) and reverse osmosis (RO) membrane treatment. The pilot system has the capacity of around 8 m 3 /h. The UF effluent is used to feed the RO membrane stage. Different mixtures of UF and RO permeates are subsequently applied for drip irrigation of various agriculture crops. The field results indicate the importance of the UF component in the removal of the organic matter and the pathogens that are still contained in the secondary effluent (the secondary effluent is obtained from a waste stabilization pond treatment system). Under specific conditions, when the dissolved solids content is relatively low, the UF effluent can be applied directly for unrestricted irrigation. In the successive RO stage most nutrients are removed, allowing applying the effluent without jeopardizing the soil fertility and the aquifers. Preliminary economic assessment indicates that the extra cost for effluent polishing via the UF stage only is in the range of 8–12 US cents/m 3 . The extra cost for the RO stage is as well assessed at 8–12 US cents/m 3 . The additional treatment expenses depend to a large extent on the quality of the incoming raw secondary effluent and local requirements at the command agricultural production sites.

There is an increasing trend to use greywater for irrigation in households. This is partly due to the notion that greywater is of better quality than wastewater and therefore does not need extensive treatment beyond addressing public health issues. The aim of the study was to evaluate the environmental impact and health risks associated with the use of greywater for irrigation on a small private farm. Over a three-year period, each of three plots on a farm was irrigated with either freshwater, fertilized water, or greywater. Irrigation water and soil from the plots were analyzed for a wide range of chemical and microbial variables. Results suggest that greywater may be of similar quality to wastewater in several parameters such as BOD and faecal coliforms. For some other variables such as boron and surfactants, greywater may even be of worse quality than wastewater. Long-term irrigation of arid loess soil with greywater may result in accumulation of salts, surfactants and boron in the soil, causing changes in soil properties and toxicity to plants. Faecal coliforms did not survive in the soil. Treating greywater before using it for irrigation is recommended, even in places where this is not a requirement.

A decision support model for the selection of treatment preferences for permeate polishing is presented. The model is based on the analytical hierarchical process that integrates multi-criteria issues into the selection of post- treatment technology for a specific seawater reverse osmosis (SWRO) plant. The objectives in using this decision-supporting tool are several, including the poor experience of the decision-maker with respect to the technology to be purchased, the high number of both qualitative and quantitative attributes that have to be considered in the selection process, and the number and variety of the alternative technologies available on the market. This paper introduces methodologies that rank the design options, provide recommendations based on permeate quality and process design, and improve the quality of information for the selection of boron removal treatment. The tool provides appropriate design guidelines for the impact of post-treatment on design and operation of SWRO plants prior to pilot and economic studies. The advantages of this approach are discussed in general terms while a specific example is presented for the Mediterranean Sea basin (Israel).

In many regions dairy farms and milk processing industries discharge large quantities of their wastes to the surroundings posing serious environmental risks. This problem is mostly faced in small dairy farms and isolated communities lacking both central collection and conventional wastewater treatment systems. Dairy wastewater is characterized by high concentrations of organic matter, solids, nutrients, as well as fractions of dissolved inorganic pollutants, exceeding those levels considered typical for high strength domestic wastewaters. With the purpose of treating the combined dairy and domestic wastewater from a small dairy farm in the Negev Desert of Israel, the use of a recent emerging technology of Immersed Membrane BioReactor (IMBR) was evaluated over the course of 500 test hours, under a variety of wastewater feed quality conditions (during the test periods, the feed BOD5 ranged from 315 ppm up to 4,170 ppm). The overall performance of a pilot-scale Ultrafiltration (UF) IMBR process for a combined domestic and dairy wastewater was analyzed based on the Data Envelopment Analysis (DEA) method. The IMBR performance in terms of membrane performance (permeate flux, transmembrane pressure, and organic removal) and DEA model (Technical Efficiency) was acceptable. DEA is an empirically based methodology and the research approach has been found to be effective in the depiction and analysis for complex systems, where a large number of mutual interacting variables are involved.

Field experiments are in progress for secondary wastewater upgrading for unrestricted utilization for agricultural irrigation. The integrative approach of secondary effluent polishing is based on using a hybrid UltraFiltration (UF) and Reverse Osmosis (RO) membrane pilot system with a capacity of around 1 m3/hr. The UF effluent is used to feed the RO membranes. The RO permeate is subsequently applied for vegetable irrigation. Field results indicate the importance of the UF component in the removal of the organic matter and the pathogens that are still contained in the secondary effluent. Under specific conditions, when the dissolved solids content is relatively low, regarding sanitary and health aspects, the UF effluent can be applied for unrestricted irrigation. During the RO stage most nutrients are removed, allowing application of the effluent without jeopardizing the soil fertility and the aquifers. Preliminary economic assessment indicates that the extra cost for effluent polishing via the UF stage only is in the range of 5 to 15 US cents/m3. The extra cost for the RO stage is also assessed at 10 to 25 US cents/m3. The additional cost depends to a large extent on the quality of the incoming raw secondary effluent and local requirements of the command region.

The scarcity of fresh water in most of the countries in the Mediterranean Basin makes treated wastewater a valuable alternative water source. The improved technology for the removal of particles, turbidity, bacteria and cysts from effluent, without the use of disinfectants is based on the use of membranes, mainly on micro-filtration (MF) and ultra-filtration (UF). Membrane treatment of secondary effluent sounds attractive since it is a stable water source. Pathogens, soluble organic matters, turbidity, color, parasites and viruses can be removed by UF membrane technology. Experiments are in progress in the commercial fields of Gadash Har Hebron Enterprise (GHHE), located near the City of Arad, Israel. Field data collected from a two-stage UF pilot plant (240 m3/day) enable us to provide performance estimate efficiencies based on the data envelopment analysis method. The research focused on individual UF experiments allowing us to determine the UF performance efficiency in terms of information quality for adequate decision-making. Field results are presented in order to support the theory and related pricing decisions.

The contamination of turfgrass by bacteriophages MS-2 and PRD-1 was assessed in the field under sprinkler irrigation (SI) and subsurface drip irrigation (SDI). No contamination of turfgrass by MS-2 was observed using SDI in the summer or winter seasons. In the summer, PRD-1 was detected in low numbers in SDI turfgrass; however, at significantly lower numbers than in SI turfgrass (p

The contents of FC, somatic coliphages and F-specific bacteriophages were measured in the stabilization pond and stabilization reservoir system of the City of Arad (Israel) in order to determine the efficiency of the treatment process regarding the microorganisms removal. Monitoring was conducted close to one year. Physical and chemical parameters (temperature, pH, BOD5, COD, SS) were also analyzed with the aim of finding factors that affect the microorganisms removal. The field results prove a very good performance of this treatment system. FC, somatic coliphages and F-specific bacteriophages were removed between 4.16 and 5.76 log units, during winter and in between 6.02 and 6.47 log units during summer. The microbial quality of the final effluent complies with the WHO guidelines for unrestricted irrigation. The results also indicate that retention time and temperature seem to be the most important factors for microorganisms removal. F-specific bacteriophages were removed at higher rates than FC and somatic coliphages. Consequently, it is suggested that F-specific bacteriophages might be less adequate viral indicators for this treatment system.

Various countries in the Mediterranean Basin and other arid and semi-arid regions are facing a gap between water supply and demand. This gap is closely linked with agricultural production and environmental issues. It is probably due to small amounts of precipitation and low availability of natural water sources. Special ventures have to be undertaken in order to supply water at adequate quality for all requirements. These can be accomplished by development of additional water sources that currently are considered marginal. The additional sources include saline ground water, treated wastewater and runoff water and are usually required to augment the limited supply from the regional conventional high quality local sources. The paper presented options for development of the marginal water sources in arid zones in conjunction with minimizing the dependence on high quality water. Domestic secondary effluent is a valuable water source for reclamation however, additional treatment is required to use it for unrestricted purposes. It can be achieved primarily by implementation of the membrane technology, namely ultrafiltration (UF) and reverse osmosis (RO) stages.