Elimination Of Micropollutants Research Articles

Investigation of Hybrid Methods for Elimination of Brilliant Blue Dye from Water Phase Using Various Nanomaterials Combined with Activated Sludge and Duckweed.

The main goal of this experimental work is screening of different natural and synthetic nanomaterials and biopolymers that may improve elimination of stable micropollutants from water phase. In this work, as a target chemical acting as the micropollutant molecule, the Brilliant Blue (BB) dye was selected. We tested different active matrices dispersed in water phase including activated carbon (AC), lyophilized graphene oxide (GO), β-cyclodextrin (CD), raw dandelion pappus (DP), microcrystalline cellulose(MC), and raw pine pollen (PP), as well as two types of Egyptian Blue mineral pigments (EB1 and EB2). Graphene oxide and Egyptian Blue nanomaterials were synthesized in our laboratory. We investigated potential application of such nanoparticles and biopolymer conglomerates as additives that may tune the activated sludge (AS) microorganisms or duckweed water plant (DW) and increase efficiency of micropollutants removal from wastewater. Studied nanomaterials/biopolymers were used in two different experimental modes involving real activated sludge microorganisms (24 h experiment) as well as duckweed plant (16 day experiment). Quantitative data of BB were obtained using microfluidic type device based on micro-TLC plate. This approach enabled direct determination of target component without sample pre-treatment like pre-concentration or pre-purification. Within single analytical run calibration line, retention standard spots (methyl red) and multiple samples were analyzed simultaneously. Due to the multivariate nature of these experiments, quantitative data were explored with chemometric tools including AHC (agglomerative hierarchical clustering), PCA (principal component analysis), and FA (factor analysis). Experimental data and multivariate calculations revealed that BB is strongly resistant on biodegradation, however, inclusion complexes formation with β-cyclodextrinmay induce degradation of this dye in the presence of duckweed. It is hoped that results of our experimental work can be used for designing of future experiments for fast screening of different additives and improvement of technological processes, focusing on purification of sewage and water from micropollutants.

Hollow-structured amorphous prussian blue decorated on graphitic carbon nitride for photo-assisted activation of peroxymonosulfate

Heterogeneous activation of peroxymonosulfate (PMS) is one of the most promising techniques for wastewater treatment. Herein, an ingenious system by coupling of photocatalysis and PMS activation was developed, using hollow-structured amorphous prussian blue (A-PB) decorated on graphitic carbon nitride (g-C3N4) as the catalyst. Degradation of bisphenol A (BPA) via the A-PB-g-C3N4 mediated PMS activation under visible light (Vis) was systematically investigated. Astonishingly, it was found that ~ 82.0%, 92.6%, 98.2% and 99.3% of BPA (40 mg/L) were removed within 2, 4, 6 and 7 min, respectively, suggesting the extremely strong oxidizing capacity of the A-PB-g-C3N4/PMS/Vis system. Synergistic effect between the decorated A-PB and the g-C3N4 substrate promoted the Fe(III)/Fe(II) redox cycling and facilitated the charge transfer at the A-PB/g-C3N4 heterojunction interface. As a result, both photocatalysis and heterogeneous activation of PMS were boosted in the A-PB-g-C3N4/PMS/Vis system, leading to the production of large amount of reactive oxygen species (ROS). The various ROS (SO4•–, HO•, •O2– and 1O2) was responsible for the ultrafast degradation of BPA. Moreover, the A-PB-g-C3N4 catalyst also exhibited outstanding reusability and stability, retaining 98.9% of the removal percentage for BPA after five consecutive reaction cycles. This study suggests that the A-PB-g-C3N4 can be an all-rounder to bridge photocatalysis and PMS activation, and shed a new light on the application of multiple ROS for the ultrafast elimination of micropollutants from wastewater.

Removal of 27 micropollutants by selected wetland macrophytes in hydroponic conditions

In this work, the primary focus is given on a mixture of 27 micropollutants (pharmaceuticals, pesticides, herbicides, fungicides and others) and its removal from aqueous solution by phytoremediation. Phytoremediation belongs to technologies, which are contributing on removal of micropollutants from wastewater in constructed wetlands. Constructed wetlands can be used as an additional step for elimination of micropollutants from municipal medium-sized wastewater treatment plants. To our knowledge, such a broad variety of micropollutants was never targeted for removal by phytoremediation before. In this work, we carry out experiments with 3 emergent macrophytes: Phragmites australis, Iris pseudacorus and Lythrum salicaria in hydroponic conditions. The selected plants are exposed to mixture of micropollutants in concentrations 1–14 mg/l for a time period of 30 days. The highest affinity for phytoremediation is detected at groups of fluorosurfactants (removal rate up to 30%), beta-blockers (removal rate up to 50%) and antibiotics (removal rate up to 90%). The leading capability for micropollutant uptake is detected at Lythrum salicaria, where 25 out of 27 compounds are removed with more than 20% efficiency. The results demonstrate well usefulness of this technology e.g. in an additional treatment step, because the mentioned groups of micropollutants are removed with comparable or even higher effectivity, than it is in case of conventional wastewater treatment plants.

A review of the adsorption-biological hybrid processes for the abatement of emerging pollutants: Removal efficiencies, physicochemical analysis, and economic evaluation

The limited efficiency of conventional wastewater treatment plants (WWTPs) in emerging pollutants (EPs) removal encourages the development of alternative technologies for the adequate treatment of wastewater, due to its adverse effects on human health and ecosystems. The biological, physical or chemical hybrid technologies to treat EPs results interesting since they can enhance the performance of WWTPs. Among them, hybrid adsorption/biological technology could offer different possibilities that are explored in this work (PAC-MBR, PACT/GAC-CAS, BAC configurations). In this way, different variations in the adsorption process have been considered: the form of the adsorbent, the feed to the system, and the type of biological process, either conventional activated sludge (CAS), membrane bioreactor (MBR) or biofilm systems. For each combination, the removal efficiency of micropollutants, classified according to their use into pharmaceuticals, personal care products (PCPs) and other micropollutants (mainly benzotriazoles) was analysed. From reported data, it was observed a beneficial synergistic effect of dipole moment and octanol-water partition coefficient on the removal efficiency of micropollutants by adsorption/biological hybrid technology. Finally, a preliminary economic evaluation of the powdered activated carbon in a conventional activated sludge reactor (PACT), powdered activated carbon-membrane bioreactor (PAC-MBR) and biological activated carbon (BAC) hybrid systems was carried out by analysing the capital expenditure (CAPEX) of plants for capacities up to 75,000 m3d-1. Likewise, estimations of adsorbent concentration for a hypothetical plant with a capacity of 10,000 m3d-1 is presented. Among these hybrid configurations, PAC-MBR achieved the highest micropollutant elimination percentages; however, it presents the highest CAPEX and activated carbon requirements.

An integrated approach using ozone nanobubble and cyclodextrin inclusion complexation to enhance the removal of micropollutants

Ozone (O3) has been widely used for the elimination of recalcitrant micropollutants in aqueous environments, due to its strong oxidation ability. However, the utilization efficiency of O3 is constrained by its low solubility and short half-life during the treatment process. Herein, an integrated approach, using nanobubble technology and micro-environmental chemistry within cyclodextrin inclusion cavities, was studied in order to enhance the reactivity of ozonisation. Compared with traditional macrobubble aeration with O3 in water, nanobubble aeration achieved 1.7 times higher solubility of O3, and increased the mass transfer coefficient 4.7 times. Moreover, the addition of hydroxypropyl-β-cyclodextrin (HPβCD) further increased the stability of O3 through formation of an inclusion complex in its molecule-specific cavity. At a HPβCD:O3 molar ratio of 10:1, the lifespan of O3 reached 18 times longer than in a HPβCD-free O3 solution. Such approach accelerated the removal efficiency of the model micropollutant, 4-chlorophenol by 6.9 times, compared with conventional macrobubble ozonation. Examination of the HPβCD inclusion complex by UV–visible spectroscopy and Nuclear Magnetic Resonance analyses revealed that both O3 and 4-chlorophenol entered the HPβCD cavity, and Benesi-Hildebrand plots indicated a 1:1 stoichiometry of the host and guest compounds. Additionally, molecular docking simulations were conducted in order to confirm the formation of a ternary complex of HPβCD:4-chlorophenol:O3 and to determine the optimal inclusion mode. With these results, our study highlights the viability of the proposed integrated approach to enhance the ozonation of organic micropollutants.

Effect-based evaluation of ozone treatment for removal of micropollutants and their transformation products in waste water

ABSTRACT The aim of this interdisciplinary research project in North Rhine-Westphalia (NRW), Germany, entitled “Elimination of pharmaceuticals and organic micropollutants from waste water” involved the conception of cost-effective and innovative waste-water cleaning methods. In this project in vitro assays, in vivo assays and chemical analyses were performed on three municipal waste-water treatment plants (WWTP). This publication focuses on the study of the in vitro bioassays. Cytotoxic, estrogenic, genotoxic and mutagenic effects of the original as well as enriched water samples were monitored before and after wastewater treatment steps using MTT and PAN I, ER Calux and A-YES, micronucleus and Comet assays as well as AMES test. In most cases, the measured effects were reduced after ozonation, but in general, the biological response depended upon the water composition of the WWTP, in particular on the formed by-products and concentration of micropollutants. In order to be able to assess the genotoxic and/or mutagenic potential of waste-water samples using bioassays like Ames test, Comet assay or micronucleus test an enrichment of the water sample via solid-phase extraction is recommended. This is in agreement with previous studies such as the “ToxBox”-Project of the Environmental Agency in Germany.

A module-based approach for elimination of organic micropollutants at wastewater treatment plants.

A technical feasibility study was carried out at the wastewater treatment plant (WWTP) Hamm-West in 2018, which included preliminary planning for the improvement of the plant, using different advanced wastewater technologies. The results of the technical feasibility study show that the application of activated carbon or ozone, in combination with an additional filtration system, can not only remove organic micropollutants efficiently but can also significantly improve the quality of other standard parameters in the WWTP effluent. This technical feasibility study, along with seven other studies, is part of the module-based approach the Emschergenossenschaft and Lippeverband (EGLV) is pursuing in order to improve wastewater treatment plants with advanced treatment systems. Finally, the module-based approach can be used to pair the most suitable WWTPs with the best applicable technologies to improve the treatment process in the whole Lippe catchment area.

A novel process for the covalent immobilization of laccases on silica gel and its application for the elimination of pharmaceutical micropollutants.

In the present work, pharmaceutical micropollutant degradation by laccase immobilized on silica through an innovative process is proposed. The influence of different parameters on the immobilization conditions was evaluated by a 23 full factorial design, and parameters leading to the highest activity were identified. Under these conditions, laccase activity reached 14 ± 2 U g-1 of silica with a protein immobilization yield of 35%. The biocatalyst characterization did not show any change in pH and thermal stabilities but enhanced the long-term storage of laccases. Immobilized T. versicolor laccases were then tested to remove four pharmaceutical micropollutants (amoxicillin, ciprofloxacin, carbamazepine, and sulfamethoxazole) in the presence of redox mediators (syringaldehyde, p-coumaric acid, and ABTS). High removal yields (50-100% according to the pollutant) were obtained within 4 h of treatment due to the synergistic effect of laccase-mediator biotransformation and adsorption on the support. Overall, the pharmaceuticals' removal efficiency was highly influenced by their physicochemical properties; however, the presence of redox mediators impacted not only the oxidation mechanism but also the interactions between the biocatalyst and micropollutants. Finally, the reusability of the biocatalyst was proved during 7 degradation cycles.

Removal of emerging micropollutants from wastewater by nanofiltration and biofilm reactor (MicroStop)

AbstractCurrent wastewater treatment is not designed for the elimination of micropollutants (MP) and therefore these are released into the aquatic environment by means of the municipal wastewater. The MicroStop project investigates a combination of a fixed‐bed reactor (FBR) and a nanofiltration plant (NF) for the elimination of organic MP. NF acts as a barrier for MP while biological degradation of the pollutants is to be induced in the FBR. A simultaneous treatment of the retentate should be realized by its return to the FBR. The NF is to be supplied with energy by a large separation of organic matter in the primary clarification. The experiments showed that NF can eliminate more than 95% of the selected and detected MP on average, and therefore, this method represents a suitable barrier for these pollutants. The retentate of the NF was used to test the potential of the biological degradation in the FBR. The test results showed that a significant biological degradation of different MP took place in the FBR. The degradability of the substances could be verified by not detecting significant adsorption on sludge and fixed‐bed. For certain MP (sulfamethoxazole and carbamazepine) only little potential of biodegradation could be detected, which is confirmed by values from the literature. Apart from these two substances, the average degradation rate was 78%. The successful MP‐retention in connection with the biological degradation rates demonstrated the potential of the concept.Statement of Industrial RelevanceIt is undisputed that the conventional wastewater treatment has to be upgraded, since it is not able to eliminate residual MP. The following describes how the MicroStop‐process is able to address MP where competitive processes such as activated carbon or ozonation fail to do so: The process is able to eliminate MP comprehensively and to retain microplastics, pathogenic germs and metabolites to a large extent before they reach the environment. The retentate, which normally occurs as residue of the NF, is directly treated in the FBR. The only residue of the MicroStop‐process would be the excess sludge, which could easily be used for sludge treatment. The effluent of the process is of high quality. This could be used in other regions of the world for irrigating plants, for industrial processes or even as tap water. The potentially increased energy consumption (i.e., due to NF) is taken into account in our concept by the carbon extraction in the primary treatment. Novelty or SignificanceThe combination of NF with biological degradation of MP in a FBR represents a process that has not yet been investigated in this form.In addition, the combination with an elevated carbon extraction in the primary treatment (Powerstep‐process) represents the idea of a complete redesign of conventional municipal wastewater treatment plants.

Sorption of pharmaceutical compounds and nutrients by various porous low cost adsorbents

In this study, the potential of eight low cost and readily available materials as adsorbents for the removal of pharmaceutically active compounds (carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBU)) and nutrients was evaluated through batch studies under various environmental conditions. Results showed that wood charcoal, light-weight expanded clay aggregate (LECA), natural zeolites and waste AAC blocks has a potential as promising adsorbents for the elimination of micro-pollutants with the sorption capacity of 0.57–2.83 mg/g for the selected compounds due to their superior properties including higher surface area, pore volume and organic content. Studies revealed that hydrogen bonding, electrostatic and ligand interaction and Vander Waals force are the predominant mechanisms responsible for the sorption process. The selected materials exhibited better removal of phosphate (70–90%) than ammonia (20–81%) and nitrate (14.1–61.8%). Surface area, pore volume, organic content, cation exchange capacity and elemental content (CaO, Al2O3, K2O and Fe2O3) significantly influenced the pollutant removal by the substrates. Being hydrophobic and anionic in nature, DCF exhibited higher removal than IBU and CBZ. Based on the results, the order of preference of material as adsorbent is: wood charcoal > natural zeolite > waste AAC blocks > LECA > blast furnace slag > natural pyrite > brickbats > sand. The results of this batch study will be helpful for selecting appropriate substrate material for the low-cost natural treatment systems where the bio-enhanced sorption/degradation processes help to eliminate the toxic emerging contaminants (ECs) from wastewater.

Lanthanum Nickel Oxide: An Effective Heterogeneous Activator of Sodium Persulfate for Antibiotics Elimination

In recent years, the presence of pharmaceutically active compounds (PhACs) in surface waters and wastewaters has b the effectiveness of conventional water treatment methods. Towards this direction, advanced oxidation processes (AOPs) for the complete elimination of micro pollutants in waters have become an emerging area of research. The present study reports the heterogeneous activation of sodium persulfate (SPS) by LaNiO3 (LNO) perovskite oxide for the degradation of sulfamethoxazole (SMX), an antibiotic agent. LNO was prepared according to a combustion method, and its physicochemical characteristics were identified by means of XRD, BET, TEM, and SEM/EDS. SMX degradation results showed the great efficiency of LNO for SPS activation. Increasing LNO and SPS dosage up to 250 mg/L enhanced the SMX degradation. In contrast, increasing SMX concentration resulted in longer time periods for its degradation. Considering the pH effect, SMX removal was obstructed under basic conditions, while the efficiency was enhanced at near-neutral conditions. The present system’s activity was also tested for piroxicam (PIR) and methylparaben (MeP) degradation, showing promising results. Unfortunately, experiments conducted in real water matrices such as bottled water (BW) and wastewater (WW), showed that SMX removal was limited to less than 25% in both cases. The hindering effects were mainly attributed to bicarbonate ions and organic matter present in aqueous media. The results obtained using suitable radical scavengers revealed the contribution of both hydroxyl and sulfate radicals in degradation reactions. Finally, LNO exhibited good stability under consecutive experimental runs.

Study of free nitrous acid (FNA)-based elimination of sulfamethoxazole: Kinetics, transformation pathways, and toxicity assessment

Free nitrous acid (FNA)-based applications have been broadly adopted in the development of novel wastewater management technologies, but a basic understanding of the effect of the chemical properties of FNA on the elimination of micropollutants is still lacking. This study aims to comprehensively evaluate FNA-based elimination of sulfamethoxazole (SMX), which is a typical species of sulphonamide antibiotics. Batch experiments were conducted under different influencing factors to investigate the antibiotics elimination processes. We found that FNA showed specific efficacy on sulphonamides characterized by sulfonamide and aniline functional groups, such as SMX. SMX degradation was affected by the initial SMX concentration, FNA concentration and solution pH and described by d[SMX]/dt=−0.29e−1.69pH[SMX]0.945[FNA]1.35. The cationic forms of SMX were more reactive towards FNA-based active components. Sulfonamide bond (S-N or C-S bonds) cleavage, nitrosubstitution, deamination and radical oxidation were proposed to be the relevant transformation pathways. The FNA-based technique was not effective for diminishing toxicity, but this process could strongly control antibacterial activity.

Removal of micropollutants from municipal wastewater using different types of activated carbons

The water reservoirs are getting polluted due to increasing amounts of micropollutants such as pharmaceuticals, organic polymers and suspended solids. Powdered activated carbon (PAC) has been proved to be a promising solution for the purification of water without having harmful impacts on the environment. Parameters such as PAC dosing, wastewater hardness, the effect of coagulant and flocculant were evaluated in a batch scale study. These parameters were further applied on a pilot plant scale for the performance evaluation of PAC based removal of micropollutants concerning the contact time and PAC dosing with main focus on recirculation of PAC sludge. The obtained optimum dose was 10–20 mg/L providing 84.40–91.30% removal efficiency of suspended solid micropollutants (MPs) and this efficiency increased to 88.90–93.00% along with coagulant which further raised by the addition of polymer and recirculation process at batch scale. On pilot plant scale, the concentration in contact reactor and PAC removal effectiveness of dissolved air flotation, lamella separator and sedimentation tank were compared. Constant optimisation resulted in a concentration ranging from 2.70 to 3.40 g/L at dosing of PAC 10 mg/L, coagulant 2.00 mg/L and polymer 0.50 mg/L. PAC doses of 10–20 mg/L with 15–30 min contact time proved best for above 70–80% elimination. The recirculation system has also proved an efficient technique because the PAC's adsorption capacity was practically completely used. Small PAC dosages yielded high micropollutants elimination.

Aluminized surface to improve solar light absorption in open reactors: Application for micropollutants removal in effluents from municipal wastewater treatment plants

This work proposes the evaluation of an aluminized surface on the bottom of open reactors to perform a photo-Fenton process, at circumneutral pH (using Fe III-Ethylenediamine-N,N′-disuccinic acid complex), for elimination of micropollutants (MPs) in real effluents from municipal wastewater treatment plants (EMWWTP). Firstly, the strategy was to initially investigate the real EMWWTP spiked with several MPs (acetaminophen, diclofenac, carbamazepine, caffeine, trimethoprim and sulfamethoxazole) with 20 and 100 μg L−1 in a laboratory scale (evaluated by HPLC-UV) using a solar simulator. Finally, the removal of all MCs present in the real EMWWTP was monitored (evaluated by HPLC-MS) in a pilot-scale (90 L) in a raceway pond reactor (RPR). The treatment time required for degradation above 80% for the investigated MPs was over 30 min, and the predominant effect could be mainly associated with organics present in the real EMWWTP due to the light attenuation and scavenging of radical species. Moreover, the results confirmed that chloride and sulfate would most likely equally not affect the process. The use of an aluminized surface on the bottom of RPRs has been confirmed as a suitable option to improve the photo-Fenton reaction, enabling the use of lower doses of iron. Up to 60 different MPs found in EMWWTP have been successfully degraded using 0.1 mM of Fe at circumneutral pH with a consumption of 30 mg L−1 H2O2 with less than 45 min.

Ecotoxicological effects of micropollutant-loaded powdered activated carbon emitted from wastewater treatment plants on Daphnia magna

In order to eliminate micropollutants from wastewater, the use of powdered activated carbon (PAC) is a suitable and common technique. Many studies already proved the successful elimination of micropollutants from wastewater using PAC. However, it still remains a challenge to completely retain the applied PAC within the wastewater treatment plant (WWTP) without considerable emission of PAC into receiving waters. The present study investigates possible toxic effects of micropollutant-loaded PAC from a WWTP in acute and chronic tests with the aquatic organism Daphnia magna. Furthermore, the well-studied micropollutant diclofenac as well as unloaded, native PAC and experimentally diclofenac-loaded PAC were tested. The acute tests resulted in median effect concentrations (EC50) after 48 h of 53 mg/L for diclofenac, 217 mg/L for native PAC and 414 mg/L for diclofenac-loaded PAC. No effects were detected for the loaded PAC from the WWTP although D. magna ingested the PAC. The chronic tests revealed that diclofenac had effects on growth, reproduction and mortality (median lethal concentration 17.0 mg/L). Exposure to native and diclofenac-loaded PAC showed clear effects on growth and a reproduction inhibition of 80% in the highest tested concentrations. The calculated reproduction EC10 values were 0.8 mg/L for native PAC and 0.3 mg/L for diclofenac-loaded PAC. For the loaded PAC from the WWTP, no effects were observed on reproduction, growth and mortality during the 21-day exposure albeit the fact that the animals ingested the PAC into their gastrointestinal system. Based on these findings PAC from WWTP can be considered as not harmful to D. magna even if complete retention of the PAC at the WWTP cannot be guaranteed.

Seasonal performance assessment of four riverbank filtration sites by combined non-target and effect-directed analysis

Targeting the most relevant organic micropollutants (OMP) in routine analysis appears difficult due to formation of transformation products of unknown concentration or toxicity. Performance assessment of water purification processes is still based upon limited target data. Therefore, we broadened the assessment of the removal efficiencies with combined non-target and effect-directed analysis at four riverbank filtration (RBF) sites in Germany. To assess micropollutant elimination, constancy and formation during different seasons, considering local redox conditions, travel distances and total component number in the river, non-target analysis features were grouped into categories. Furthermore, RBF sites were investigated with four endpoints (baseline toxicity, acetylcholinesterase inhibition, antibiotic effects and estrogenic effects) for thin-layer chromatography - effect-directed analysis for the first time. Results showed elimination or reduction of many features and effects, but also constancy and formation of varying proportions. Fall river samples showed precipitation-caused dilution in both tests. Spring samples showed increased effects only in acetylcholinesterase inhibition and estrogenic effects, probably due to phytoestrogens or algae bloom during vegetation period. Sites were ranked considering the total number of features, group proportions, seasonal variations and intensity and number of effects in abstraction wells. Oxic conditions and low initial component numbers in the river (Ruhr sites) resulted in less effects and fewer formations. Longer travel distances were important for a more efficient reduction of effects and features. Combination of non-target and effect-directed analysis proved to be valuable for a more comprehensive assessment of process performance beyond target analysis as also unknown OMP are observed with both methods.

Prompt removal of antibiotic by adsorption/electro-Fenton degradation using an iron-doped perlite as heterogeneous catalyst

In the current study, a novel-fangled sequential approach, adsorption/electro-Fenton, was developed for the elimination of micropollutants from aqueous matrixes. Therefore, the prompt removal of a pharmaceutical, sulfamethizole, by adsorption on carbonaceous materials is proposed. After that, the concentrated solution was treated by electro-Fenton using novel synthesized perlite-based catalyst. Initially, three different carbonaceous adsorbents (pellets carbonaceous nanogel doped with iron, honeycomb carbonaceous aerogel and orange biochar) were considered. The kinetics and isotherms of the pollutant adsorption were studied. The higher removal level was attained by the pellets with the adsorption process following a pseudo-2nd order model and being well defined by the Langmuir adsorption isotherm. After that, the pollutant was extracted from the pellets, concentrated in aqueous solution and treated by different advanced oxidation processes (anodic oxidation and electro-Fenton process). The results confirmed the higher efficiency of electro-Fenton treatment and its improvement was evaluated using a novel synthesized iron perlite catalyst. For this purpose, the synthesis of iron catalysts supported in perlite was performed by different methods (carbonisation, precipitation and hydrothermal). Among them, the hydrothermal synthesis produced catalysts with high catalytic activity, significant pollutant removal (>95 %), high stability and without iron leaching after several cycles of treatment. Based on these results, the development of a continuous treatment system was successfully carried out attaining high TOC removal values. Moreover, the feasibility of the treatment was also validated in complex water matrixes and toxicity assays demonstrated the viability of the proposed treatment for a global management of this pollutant.

Advanced Wastewater Treatment to Eliminate Organic Micropollutants in Wastewater Treatment Plants in Combination with Energy-Efficient Electrolysis at WWTP Mainz

To achieve the Paris climate protection goals there is an urgent need for action in the energy sector. Innovative concepts in the fields of short-term flexibility, long-term energy storage and energy conversion are required to defossilize all sectors by 2040. Water management is already involved in this field with biogas production and power generation and partly with using flexibility options. However, further steps are possible. Additionally, from a water management perspective, the elimination of organic micropollutants (OMP) is increasingly important. In this feasibility study a concept is presented, reacting to energy surplus and deficits from the energy grid and thus providing the needed long-term storage in combination with the elimination of OMP in municipal wastewater treatment plants (WWTPs). The concept is based on the operation of an electrolyzer, driven by local power production on the plant (photovoltaic (PV), combined heat and power plant (CHP)-units) as well as renewable energy from the grid (to offer system service: automatic frequency restoration reserve (aFRR)), to produce hydrogen and oxygen. Hydrogen is fed into the local gas grid and oxygen used for micropollutant removal via upgrading it to ozone. The feasibility of such a concept was examined for the WWTP in Mainz (Germany). It has been shown that despite partially unfavorable boundary conditions concerning renewable surplus energy in the grid, implementing electrolysis operated with regenerative energy in combination with micropollutant removal using ozonation and activated carbon filter is a reasonable and sustainable option for both, the climate and water protection.

Tool for selecting indicator substances to evaluate the impact of wastewater treatment plants on receiving water bodies

The elimination of organic micropollutants (OMPs) from wastewater could in future become mandatory for operators of wastewater treatment plants (WWTPs). Indicator substances are a great help and a cost-efficient way in monitoring the pollution of water bodies with OMPs caused by the discharge of WWTPs. However, with the still increasing number of OMPs in our environment, the selection of suitable indicator substances presents a challenge. A concept was developed to help identify representative indicator substances. The derived indicator substances are not only used to assess water pollution, but can also be used to calculate elimination efficiencies of WWTPs. In the present investigations, the indicator substances were used to evaluate the reduction of OMPs in the water body on the basis of the expansion of a WWTP with an ozonation plant. The transferability of the tool was verified with a second WWTP. Furthermore, the impact of the number of measurements was analysed via statistical combinatorics. With the tool, 36 substances were classified, leading to the identification of 9 suggested indicator substances. Among them ibuprofen and diclofenac attracted attention due to their ecotoxicological relevance. Detailed data analyses were carried out using principal component analysis (PCA) and loads.

Modeling and sensitivity analysis of the alkylphenols removal via moving bed biofilm reactor using artificial neural networks: Comparison of levenberg marquardt and particle swarm optimization training algorithms

Alkylphenols (APs) are nonionic surfactants with toxic and estrogenic properties. APs from municipal and industrial wastewater are frequently detected in surface waters. Therefore, a broadly accepted method for the treatment of APs is needed. The moving-bed bioreactor (MBBR) is an effective process for micropollutant elimination. In this study, the modeling of 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) removal from synthetic wastewater using MBBR was performed. Also, a comparison was made between the multilayer perceptron artificial neural network (MLPNN) trained with the traditional Levenberg Marquardt (LM) and the particle swarm optimization (PSO) algorithms. The performance of MBBR in removing chemical oxygen demand (COD) and APs was predicted using the COD surface area loading rate (SALR), COD volumetric loading rate (VLR), hydraulic retention time (HRT), and the initial concentration of APs. The results showed that the best transfer functions are Tan-sigmoid in the hidden layer and Purelin in the output layer. The number of optimal neurons was 5:9:3 for LM and 5:11:3 for PSO. Moreover, the network trained with PSO algorithm was slightly more predictive (R = 0.9997 MSE = 2.526e-5, MAE = 0.0041) than the traditional LM algorithm (R = 0.9989, MSE = 2.582e-5, MAE = 0.0043), especially by increasing the number of neurons. Finally, a sensitivity analysis was performed using ANN-PSO and Pearson correlation, and the results were completely compatible.