Óscar Clavería González

Pharmaceuticals and organic pollution mitigation in reclamation osmosis brines by UV/H2O2 and ozone.

One significant disadvantage of using reverse osmosis (RO) for reclamation purposes is the need to dispose of the RO retentates. These retentates contain a high concentration of micropollutants, effluent organic matter (EfOM) and other inorganic constituents, which are recalcitrant to biological treatment and may impact the environment. The occurrence of 11 pharmaceuticals (concentrations ranging from 0.2 to 1.6 μg L(-1)) and their mitigation in RO retentates by a UV/H2O2 process and ozonation was studied using a wide range of oxidant dosages. Eleven pharmaceuticals were identified at. Initial observed kinetic constants (kobs) were calculated for the different pharmaceuticals. Other typical wastewater parameters were also monitored during the UV/H2O2 and ozonation reactions. The range for kobs was found to be 0.8-12.8L mmol O3(-1) and 9.7-29.9 L mmol H2O2(-1) for the ozonation and UV/H2O2 process, respectively. For ozonation, Atenolol, Carbamazepine, Codeine, Trimethoprim and Diclofenac showed the lowest initial kobs (in the order mentioned). Atenolol and Carbamazepine appeared as the most ozone resistant pharmaceuticals, exhibiting the lowest percentage of elimination at low ozone doses. On the other hand, despite the non-selectivity of HO, differences in the initial kobs were also observed during the UV/H2O2 process. Trimethoprim, Paroxetine and Sulfamethoxazole exhibited the lowest initial kobs values (in the order mentioned). Trimethoprim and Paroxetine also exhibited the lowest percentage removal when low H2O2 doses were assayed. The compounds that were identified as problematic during ozonation were more efficiently removed by the UV/H2O2 process. UV/H2O2 generally appeared to be a more efficient technology for removing pharmaceuticals from RO brines compared to ozonation.

Performance of a sequencing batch biofilm reactor for the treatment of pre-oxidized sulfamethoxazole solutions.

A combined strategy of a photo-Fenton pretreatment followed by a Sequencing Batch Biofilm Reactor (SBBR) was evaluated for total C and N removal from a synthetic wastewater containing exclusively 200 mg L(-1) of the antibiotic Sulfamethoxazole (SMX). Photo-Fenton reaction was optimized at the minimum reagent doses in order to improve the biocompatibility of effluents with the subsequent biological reactor. Consequently, the pretreatment was performed with two different initial H(2)O(2) concentrations (300 and 400 mg L(-1)) and 10 mg L(-1) of Fe(2+). The pre-treated effluents with the antibiotic intermediates as sole carbon source were used as feed for the biological reactor. The SBBR was operated under aerobic conditions to mineralize the organic carbon, and the Hydraulic Retention Time (HRT) was optimized down to 8h reaching a removal of 75.7% of the initial Total Organic Carbon (TOC). The total denitrification of the NO(3)(-) generated along the chemical-biological treatment was achieved by means of the inclusion of a 24-h anoxic stage in the SBBR strategy. In addition, the Activated Sludge Model No. 1 (ASM1) was successfully used to complete the N balance determining the N fate in the SBBR. The characterization and the good performance of the SBBR allow presenting the assessed combination as an efficient way for the treatment of wastewaters contaminated with biorecalcitrant pharmaceuticals as the SMX.

Advanced UV/H2O2 oxidation of deca-bromo diphenyl ether in sediments

Removal of BDE-209 from contaminated sediments by UV/H2O2 treatment was investigated under different reaction conditions (different UV irradiance and H2O2 concentrations). After 10h of UV/H2O2 treatment, 90% of BDE-209 was removed with a half-life time (t1/2) of 3.5h and a kinetic constant (k) of 0.22 h(-1). Possible formation of OH-PBDEs and debrominated polybromodiphenyl ethers was investigated by GC-MS and LC-MS/MS. None of the abovementioned BDE-209 by-products was found after 2.5, 5.5 and 10h of UV/H2O2 treatment. Toxicity experiments carried out with zebrafish embryos exposed to the sediment before and after the UV/H2O2 treatment did not show any morphological or behavioural alterations, suggesting that no putative debrominated or oxidation products were originated by the treatment in concentrations high enough to elicit significant toxic effects in zebrafish embryos.

Bacterial community characterization of a sequencing batch reactor treating pre-ozonized sulfamethoxazole in water.

Antibiotics are pharmaceutical compounds widely used to treat a broad range of infections. These chemicals appear to be recalcitrant compounds when released to water systems, and their presence at the effluent of wastewater treatment plants and surface waters has been widely documented. Sulfamethoxazole (SMX), a sulfonamide commonly used to treat urinary infections, is one of them. Ozonation was proved to be a suitable method to remove SMX antibiotic in water. However, it is stated that a high ozone dosage would be necessary to achieve the complete mineralization of the intermediates. In this work, ozonation is coupled with a Sequencing Batch Biofilm Reactor (SBBR) in order to completely degrade SMX and its metabolites from water solutions. Moreover, a precise description of the microbial community in the bioreactor is provided by means of traditional microscopy and molecular biology techniques. The results obtained showed high Total Organic Carbon removals at the end of the biological treatment (89% removal). Furthermore, nitrates produced during the aerobic SBBRs performance were monitored and eliminated by adding an anoxic stage, achieving an overall nitrogen removal of 86%. A bacterial community analysis of the SBBR during aerobic and aerobic-anoxic conditions was performed, targeting the bacterial 16S ribosomal ribonucleic acid (rRNA) gene. These results revealed a dominant contribution of bacteria from the Proteobacteria class, with a major contribution from the Rhizobiales and Burkholderiales orders during the bioreactor performance, counting 52% of the total population.

Degradation kinetics and pathways of three calcium channel blockers under UV irradiation

Calcium channel blockers (CCBs) are a group of pharmaceuticals widely prescribed to lower blood pressure and treat heart diseases. They have been frequently detected in wastewater treatment plant (WWTP) effluents and downstream river waters, thus inducing a potential risk to aquatic ecosystems. However, little is known about the behavior and fate of CCBs under UV irradiation, which has been adopted as a primary disinfection method for WWTP effluents. This study investigated the degradation kinetics and pathways of three commonly-used CCBs, including amlodipine (AML), diltiazem (DIL), and verapamil (VER), under UV (254 nm) irradiation. The chemical structures of transformation byproducts (TBPs) were first identified to assess the potential ecological hazards. On that basis, a generic solid-phase extraction method, which simultaneously used four different cartridges, was adopted to extract and enrich the TBPs. Thereafter, the photo-degradation of target CCBs was performed under UV fluences typical for WWTP effluent disinfection. The degradation of all three CCBs conformed to the pseudo-first-order kinetics, with rate constants of 0.031, 0.044 and 0.011 min(-1) for AML, DIL and VER, respectively. By comparing the MS(2) fragments and the evolution (i.e., formation or decay) trends of identified TBPs, the degradation pathways were proposed. In the WWTP effluent, although the target CCBs could be degraded, several TBPs still contained the functional pharmacophores and reached peak concentrations under UV fluences of 40-100 mJ cm(-2).

Reverse osmosis concentrate treatment by chemical oxidation and moving bed biofilm processes

In the present work, four oxidation techniques were investigated (O3, O3/UV, H2O2/O3, O3/H2O2/UV) to pre-treat reverse osmosis (RO) concentrate before treatment in a moving-bed biofilm reactor (MBBR) system. Without previous oxidation, the MBBR was able to remove a small fraction of the chemical oxygen demand (COD) (5-20%) and dissolved organic carbon (DOC) (2-15%). When the concentrate was previously submitted to oxidation, DOC removal efficiencies in the MBBR increased to 40-55%. All the tested oxidation techniques improved concentrate biodegradability. The concentrate treated by the combined process (oxidation and MBBR) presented residual DOC and COD in the ranges of 6-12 and 25-41 mg L(-1), respectively. Nitrification of the RO concentrate, pre-treated by oxidation, was observed in the MBBR. Ammonium removal was comprised between 54 and 79%. The results indicate that the MBBR was effective for the treatment of the RO concentrate, previously submitted to oxidation, generating water with an improved quality.

Biodegradation of Photo-Fenton Pre-Treated Solutions of Sulfamethoxazole by Aerobic Communities. Molecular Biology Techniques Applied to the Determination of Existing Strains

Abstract This work is focused in the combination of a photo-Fenton process and biological treatments in different devices for the degradation of a 200 mg.L-1 Sulfamethoxazole (SMX) solution. Firstly, the combination of a photo-Fenton process, carried out with different initial H2O2 concentrations, with an aerobic biological treatment performed in a 1 L suspended biomass batch reactors was carried out. A relationship between the degree of pre-treatment and the overall TOC removals achieved was found. Secondly, a photo-Fenton pre-treatment carried out with an initial H2O2 concentration of 300 mg.L-1 and 10 mg.L-1 of Fe2+, was selected to feed a Sequencing Batch Biofilm Reactor (SBBR). It was possible to work with stable cycles of 24 hours, degrading 75% of the TOC contained in the initial SMX solution. Bacterial community located in the biofilm was successfully characterized by applying molecular biology techniques and Scanning Electron Microscopy (SEM).

Combination of photo-Fenton and biological SBBR processes for sulfamethoxazole remediation

A combined strategy of a photo-Fenton pretreatment followed by a Sequencing Batch Biofilm Reactor (SBBR) was evaluated for total C and N removal from a synthetic wastewater containing 200 mg L(-1) of the antibiotic Sulfamethoxazole (SMX). Photo-Fenton reaction was performed with two different H2O2 concentrations (300 and 400 mg L(-1)) and 10 mg L(-1) of Fe2+. The pre-treated effluents with the antibiotic intermediates as sole carbon source, together with a nutrients solution, were used as feed for the biological reactor. The SBBR was operated under aerobic conditions to mineralize the organic carbon and the hydraulic retention time (HRT) was optimized down to 8 hours. Then, an anoxic denitrification stage of 24 hours of HRT was added right after the aerobic stage of the same duration in order to remove the NO3(-) generated along the chemical-biological treatment. TOC, COD and SMX concentrations together with O2 uptake rate (OUR) profiles were monitored in purpose of assessing the performance of the system. NO3(-), NH4+ and total N concentrations were analyzed to find out the fate of N contained in the initial SMX molecule. A start up strategy resulted in the correct formation of a biofilm over the volcanic support. The total TOC removals achieved with the combination of the chemical and the biological processes were 75.7 and 87.7% for the low and the high H2O2 concentration pretreatments respectively. Practically all N present in the SMX solution was eliminated in the SBBR when the aerobic-anoxic strategy was used.

Treatment Technologies for Wastewater Reuse: Fate of Contaminants of Emerging Concern

The presence of thousands of microcontaminants in wastewaters and their potential risks has drawn a large attention of the scientific community during the last years. The presence of these contaminants is especially controversial when wastewater is considered for reuse because a large number of microcontaminants are frequently not totally removed by conventional wastewater treatment processes. As a contribution to the knowledge in this field, this chapter focuses on the application of four well-known and widely used technologies to the elimination of microcontaminants. Membranes, activated carbon, ozonation, and advanced oxidation processes (AOPs) are deeply reviewed to assess their efficiency and safety in the elimination of these contaminants from wastewater effluents. A brief description of each technology is presented together with a review of their real application, mostly in wastewater treatment plants (WWTPs). A deep analysis of the found data allows to conclude that the four presented alternatives can be useful for microcontaminant mitigation although none of them seem to be a universal barrier for microcontaminants when used separately. In addition, each technology presents drawbacks which demand further research to be overcome. Depending on the final use of reclaimed water, the treatment may require the combination of several of the studied technologies although that results in an economic impact which cannot be neglected.

A Comparison of the Environmental Impact of Different AOPs: Risk Indexes

Today, environmental impact associated with pollution treatment is a matter of great concern. A method is proposed for evaluating environmental risk associated with Advanced Oxidation Processes (AOPs) applied to wastewater treatment. The method is based on the type of pollution (wastewater, solids, air or soil) and on materials and energy consumption. An Environmental Risk Index (E), constructed from numerical criteria provided, is presented for environmental comparison of processes and/or operations. The Operation Environmental Risk Index (EOi) for each of the unit operations involved in the process and the Aspects Environmental Risk Index (EAj) for process conditions were also estimated. Relative indexes were calculated to evaluate the risk of each operation (E/NOP) or aspect (E/NAS) involved in the process, and the percentage of the maximum achievable for each operation and aspect was found. A practical application of the method is presented for two AOPs: photo-Fenton and heterogeneous photocatalysis with suspended TiO2 in Solarbox. The results report the environmental risks associated with each process, so that AOPs tested and the operations involved with them can be compared.