Yaal Lester

Sulfamethoxazole contamination of a deep phreatic aquifer

Groundwater samples were obtained from the water table region of a phreatic aquifer (unsaturated zone depth up to 28 m) under land irrigated with wastewater effluents for about 5 decades and a relatively deep pumping well (109 m), used as a drinking water source till 2007, located downstream (1300 m) of wastewater effluent and sludge infiltration facilities. Sulfamethoxazole (SMX) concentrations in secondary effluents varied between 90 and 150 ng/L. SMX was extracted using SPE and was analyzed by HPLC-MS/MS. SMX (maximum concentration of 37 ng/L) was detected in the water table region, in two monitoring wells, after an unsaturated zone transport period of about 16 years. The maximum SMX concentration detected in the pumping well was of 20 ng/L. These results question wastewater effluent disposal strategies including the suitability of irrigation with effluents on the replenishment area of an aquifer supplying drinking water.

pH induced polychromatic UV treatment for the removal of a mixture of SMX, OTC and CIP from water

Water and wastewater effluents contain a vast range of chemicals in mixtures that have different chemical structures and characteristics. This study presents a treatment technology for the removal of mixtures of antibiotic residues (sulfamethoxazole (SMX), oxytetracycline (OTC) and ciprofloxacin (CIP)) from contaminated water. The treatment combines pH modification of the water to an optimal value, followed by a photolytic treatment using direct polychromatic ultraviolet (UV) irradiation by medium pressure UV lamp. The pH adjustment of the treated water leads to structural modifications of the pollutants molecule thus may enhance direct photolysis by UV light. Results showed that an increase of water pH from 5 to 7 leads to a decrease in degradation rate of SMX and an increase in degradation rate of OTC and CIP, when studied separately and not in a mixture. Thus, the optimal pH values for UV photodegradation in a mixture, involve initial photolysis at pH 5 and then gradually changing the pH from 5 to 7 during the UV exposure. For example, this resulted in 99% degradation of SMX at pH 5 and enhanced degradation of OTC and CIP from 54% and 26% to 91% and 96% respectively when pH was increased from 5 to 7. Thus the pH induced photolytic treatment has a potential in improving treatment of antibiotics in mixtures.

Photodegradation of the antibiotic sulphamethoxazole in water with UV/H2O2 advanced oxidation process

Photodegradation of the antibiotic sulphamethoxazole (SMX) in water using a medium‐pressure UV lamp combined with H2O2 (UV/H2O2) was used to generate the advanced oxidation process (AOP). The photodegradation process was steadily improved with addition of H2O2 at relatively low to moderate concentrations (5 to 50 mg L−1). However, the addition of H2O2 to the photolysis process at higher concentrations (50 to 150 mg L−1) did not improve the degradation rate of SMX (in comparison with 50 mg L−1 H2O2). Addition of H2O2 to the UV photolysis process resulted in several processes occurring concurrently as follows: (a) formation of HO· radicals which contributed to the SMX degradation, (b) decrease in the available light for direct UV photolysis of SMX, and (c) scavenging of the HO· radicals by H2O2, which was highly dominant at moderate to high concentrations of H2O2. It is clear that these factors, separately and synergistically, and possibly others such as by‐product formation, affect the overall difference in SMX degradation in the AOP process at different H2O2 concentrations.

Treating wastewater from a pharmaceutical formulation facility by biological process and ozone

Wastewater from a pharmaceutical formulation facility (TevaKS, Israel) was treated with a biological activated-sludge system followed by ozonation. The goal was to reduce the concentrations of the drugs carbamazepine (CBZ) and venlafaxine (VLX) before discharging the wastewater to the municipal wastewater treatment plant (WWTP). Both drugs were detected at extremely high concentrations in TevaKS raw wastewater ([VLX]=11.72 ± 2.2mg/L, [CBZ]=0.84 ± 0.19 mg/L), and resisted the biological treatment. Ozone efficiently degraded CBZ: at an O3 dose-to-dissolved organic carbon ratio of 0.55 (O3/DOC), the concentration of CBZ was reduced by >99%. A lower removal rate was observed for VLX, which was decreased by ≈ 98% at the higher O3/DOC ratio of 0.87. Decreasing the pH of the biologically treated effluent from 7 to 5 significantly increased the ozone degradation rate of CBZ, while decreasing the degradation rate of VLX. Ozone treatment did not alter the concentration of the effluents DOC and filtered chemical oxygen demand (CODf). However, a significant increase was recorded (following ozonation) in the effluents biological oxygen demand (BOD5) and the BOD5/CODf ratio. This implies an increase in the effluents biodegradability, which is highly desirable if ozonation is followed by a domestic biological treatment. Different organic byproducts were formed following ozone reaction with the target pharmaceuticals and with the effluent organic matter; however, these byproducts are expected to be removed during biological treatment in the municipal WWTP.

Removal of pharmaceuticals using combination of UV/H2O2/O3 advanced oxidation process

Water and wastewater effluents contain a vast range of pharmaceutical chemicals. The present study aims to determine the potential of the advanced oxidation technology UV/H(2)O(2)/O(3) and its sub-processes (i.e. UV, UV/H(2)O(2), UV/O(3), O(3) and H(2)O(2)/O(3)) for the degradation of the antibiotics ciprofloxacin (CIP) and trimethoprim (TMP), and the antineoplastic drug cyclophosphamide (CPD) from water. Creating AOP conditions improved in most cases the degradation rate of the target compounds (compared with O(3) and UV alone). H(2)O(2) concentration was found to be an important parameter in the UV/H(2)O(2) and H(2)O(2)/O(3) sub-processes, acting as (•)OH initiator as well as (•)OH scavenger. Out of the examined processes, O(3) had the highest degradation rate for TMP and H(2)O(2)/O(3) showed highest degradation rate for CIP and CPD. The electrical energy consumption for both CIP and CPD, as calculated using the E(EO) parameter, was in the following order: UV > UV/O(3) > UV/H(2)O(2)/O(3) > O(3) > H(2)O(2)/O(3). Whereas for TMP O(3) was shown to be the most electrical energy efficient. Twelve degradation byproducts were identified following direct UV photolysis of CIP.

Production of photo-oxidants by dissolved organic matter during UV water treatment.

Dissolved organic matter (DOM) irradiated by sunlight generates photo-oxidants that can accelerate organic contaminant degradation in surface waters. However, the significance of this process to contaminant removal during engineered UV water treatment has not been demonstrated, partly due to a lack of suitable methods in the deep UV range. This work expands methods previously established to detect (1)O2, HO•, H2O2, and DOM triplet states ((3)DOM*) at solar wavelengths to irradiation at 254 nm, typical of UV water treatment. For transient intermediates, the methods include a photostable probe combined with selective scavengers. Quantum yields for (1)O2, (3)DOM* and H2O2 were in the same range as for solar-driven reactions but were an order of magnitude higher for HO•, which other experiments indicate is due to H2O2 reduction. With the quantum yields, the degradation of metoxuron was successfully predicted in a DOM solution irradiated at 254 nm. Further modeling showed that the contribution of DOM sensitization to organic contaminant removal during UV treatment should be significant only at high UV fluence, characteristic of advanced oxidation processes. Of the reactive species studied, (3)DOM* is predicted to have the greatest general influence on UV degradation of contaminants.

Influence of wastewater particles on ozone degradation of trace organic contaminants.

In this Article, we demonstrate the influence of effluent particles (in the range of <50 μm) on ozone degradation of trace organic contaminants (TrOCs) and effluent-quality parameters. Secondary effluent was filtered through different pore-size filters and ozonated at various ozone doses. Degradation of both ozone-reactive and ozone-refractory contaminants improved following ozonation of effluent filtered with smaller pore size filters, indicating that particles in this range may adversely affect ozonation. The inhibitory effect of particles was attributed to their reaction with ozone, reducing available ozone and HO(•) radicals. In addition, increasing filtration level decreased the effluents (instantaneous) ozone demand and increased removal of effluent UV absorbance (UVA254), further establishing that ozone reacts with effluent particles, in competition with dissolved matter. Moreover, ozone was shown to react with particles even during the first seconds of the process, suggesting a high rate of some ozone-particle reactions, comparable to ozone reaction with highly reactive dissolved organic matter moieties. Particle image analysis revealed that particle formation/aggregation and particle disintegration occurs simultaneously during wastewater (WW) ozonation. Our study implies that particles could affect the efficiency of WW ozonation, by increasing the effluents ozone demand and decreasing contaminant degradation.

Demonstrating sucralose as a monitor of full-scale UV/AOP treatment of trace organic compounds

Due to the large number of trace organic compounds (TOrCs) in water and wastewater, their degradation during UV-based advanced oxidation (UV/AOP) is best monitored using a conservative indicator compound. The present study demonstrates the in situ use of sucralose, a widely consumed artificial sweetener, as a conservative probe for UV/AOP degradation of TOrCs. The main qualities of sucralose in this regard are its high concentration in wastewater effluent and surface water (enabling its direct detection), its resistance to direct UV photolysis, and its relatively slow reaction with hydroxyl radical. Degradation of sucralose was compared to the degradation of commonly detected TOrCs, across two AOPs (i.e. UV/H2O2 and UV/NO3), in both lab-scale and pilot-scale systems. In all cases, UV/AOP degradation of sucralose was slower than the degradation of the examined TOrCs, and is expected to be slower than the degradation of the majority of other environmentally relevant TOrCs. These results demonstrate the potential of sucralose as a conservative probe, to monitor the transformation of TOrCs during UV/AOP treatment. Furthermore, degradation of sucralose was slower than the degradation of many transformation products (generated during oxidation of TOrCs), implying that sucralose is also a valuable indicator for the decay of primary transformation products.

Photodegradation of sulphadimethoxine in water by medium pressure uv lamp

The photodegradation rate of sulphadimethoxine (SMT) in water was studied under polychromatic UV light, in a bench scale apparatus. SMT photolysis was carried out at pH levels of 2.5, 6.5 and 10 to study the impact of acid base properties on the degradation of SMT. The highest SMT photolysis fluence based rate was found at pH=2.5 (k=7.22x10(-4) cm2/mJ) and the lowest rate at pH=10 (k=4.72x10(-4) cm2/mJ), thus the reaction rate decreases with an increase in pH between pH values of 2.5-10. Results indicated that direct photolysis is not satisfactory for degradation of SMT by polychromatic UV lamp as a fluence of approximately 7,000 mJ/cm2 is needed to break down 99% of SMT at pH 6.5. The photodegradation products of SMT were studied at various pH values. Photodegradation of SMT results in dissimilar relative amounts of intermediates formed at different pH values which may exert a photon demand and impact on SMT photodegradation rate.

Enhanced Removal of Micropollutants from Groundwater, Using pH Modification Coupled with Photolysis

Direct ultraviolet (UV) photolysis coupled with modification of solution pH was explored as a method for the removal of organic micropollutants from groundwater. Photodegradation rates of most of the investigated compounds were pH dependent, however, its correlation with photodegradation rate varied among compounds. The potential of the pH modification during photolysis was determined for removal of a mixture of two pharmaceuticals sulfamethoxazole (SMX) and triclosan (TCS) in groundwater. The treatment included initial photolysis of the mixture at the optimal pH for TCS (i.e., 7.5–7.9), followed by pH modification to the optimal pH for SMX (i.e., 5), prior to a second irradiation period. The described procedure dramatically increased the removal efficiency (up to threefold) of the treated mixture compared to UV treatment at constant pH.