Wastewater Treatment Procedures Research Articles

Survival and growth of saprotrophic and mycorrhizal fungi in recalcitrant amine, amide and ammonium containing media.

The elimination of hazardous compounds in chemical wastes can be a complex and technically demanding task. In the search for environmental-friendly technologies, fungal mediated remediation and removal procedures are of concern. In this study, we investigated whether there are fungal species that can survive and grow on solely amine-containing compounds. One compound containing a primary amine group; 2-diethylaminoethanol, one compound with a primary amide group; 2,6-dichlorobenzamide (BAM), and a third compound containing a quaternary ammonium group; N3-trimethyl(2-oxiranyl)methanaminium chloride, were selected. The choice of these compounds was motivated by their excessive use in large scale manufacturing of protein separation media (2-diethylaminoethanol and the quaternary amine). 2,6-dichlorobenzamide, the degradation product of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), was chosen since it is an extremely recalcitrant compound. Utilising part of the large fungal diversity in Northern European forests, a screening study using 48 fungal isolates from 42 fungal species, including saprotrophic and mycorrhizal fungi, was performed to test for growth responses to the chosen compounds. The ericoid (ERM) mycorrhizal fungus Rhizoscyphus ericae showed the best overall growth on 2-diethylaminoethanol and BAM in the 1-20 g L-1 concentration range, with a 35-fold and 4.5-fold increase in biomass, respectively. For N3-trimethyl(2-oxiranyl)methanaminium chloride, the peak growth occurred at 1 g L-1. In a second experiment, including three of the most promising fungi (Laccaria laccata, Hygrophorus camarophyllus and Rhizoscyphus ericae) from the screening experiment, a simulated process water containing 1.9% (w/v) 2-diethylaminoethanol and 0.8% (w/v) N3-trimethyl(2-oxiranyl)methanaminium chloride was used. Laccaria laccata showed the best biomass increase (380%) relative to a control, while the accumulation for Rhizoscyphus ericae and Hygrophorus camarophyllus were 292% and 136% respectively, indicating that mycorrhizal fungi can use amine- and amide-containing substrates as nutrients. These results show the potential of certain fungal species to be used in alternative green wastewater treatment procedures.

Pharmaceutical Residues in Senior Residences Wastewaters: High Loads, Emerging Risks.

Senior residences are health-care facilities that are socially-accepted for the assistance of elderly people. Since the elderly account for the foremost pharmaceutical-consuming age-group, senior residences become a hot-spot for pharmaceuticals discharge to the sewage grid. The objectives of the present study were to identify the bioactive pharmaceuticals in sewage waters from senior residences and to propose an on-site monitoring strategy for their control. In this study, we have studied the presence of 43 pharmaceuticals highly consumed by the elderly population in six senior residences located in Spain, France and Portugal. Wastewater was sampled directly from the water-chest in each residence during different times of the day throughout one week. Main compounds detected at the high µg L−1 level were analgesic and antipyretic drugs such as acetylsalicylic acid, paracetamol, ibuprofen; antibiotics such as amoxicillin and sulfamethoxazole; compounds for the treatment of neuropathies as gabapentin, trazodone and valsartan; pharmaceuticals for the treatment of diabetes (vildagliptin) and anticancer drugs. The daily loads discharged were estimated and their fate was evaluated. The final objective of this study is to highlight the need to implement at-source waste water treatment procedures in senior residences, which have been identified as a point source pollution of pharmaceuticals.

The impact of silver sulfide nanoparticles and silver ions in soil microbiome

The use of biosolids as fertilizers in agriculture can lead to the exposure of soil biota to sulfidised silver nanoparticles (Ag2S NPs), generated during the wastewater treatment procedures. Considering the crucial role of microorganisms on soil functions, we aimed to study the effects of 10 mg kg−1 soil of Ag2S NPs or AgNO3 on the soil microbiome, using an indoor mesocosm. After 28 days of exposure, Ag2S NPs induced a significant change in the soil microbiome structure, at class, genera and OTU levels. For instance, a significantly higher abundance of Chitinophagia, known for its lignocellulose-degrading activity, was observed in Ag2S NPs-treated soil toward the control. Nevertheless, stronger effects were observed in AgNO3-treated soil, over time, due to its higher silver dissolution rate in porewater. Additionally, only the AgNO3-treated soil stimulates the abundance of ammonia-oxidizing (AOB; amoA gene) and nitrite-oxidizing (NOB; nxrB gene) bacteria, which are involved in the nitrification process. Distinct variants of amoA and nxrB genes emerged in silver-treated soils, suggesting a potential succession of AOB and NOB with different degree of silver-tolerance. Our study highlights the latter effects of Ag2S NPs on the soil microbiome composition, while AgNO3 exerted a stronger effect in both composition and functional parameters.

Removal of emerging micropollutants originating from pharmaceuticals and personal care products (PPCPs) in water and wastewater by advanced oxidation processes: A review

Because of their intrinsic potential to produce metabolic effects on the human body at smaller concentrations, pharmaceuticals and personal care products (PPCPs) are a distinct category of emerging environmental pollutants. Due to their widespread intake, limited metabolic capacity, and indecorous disposal, PPCPs pollutants are commonly found in water supplies and wastewater treatment plants. If partly oxidized PPCPs are introduced into wastewater treatment plants, they will disrupt biological wastewater treatment procedures. As a result, traditional wastewater treatment plants are inadequate for PPCPs elimination. PPCPs have been effectively eliminated using advanced oxidation methods such as electrochemical oxidation, ultrasonication, and ionizing radiation. This review summarizes recent studies on the removal of PPCPs by advanced oxidation processes, as well as knowledge useful for applying these processes in water and wastewater treatment. The degradation of different classes of PPCPs has been reviewed to analyze (i) significant factors — initial concentration of PPCPs, ultrasonication power, radiation dose, current density, temperature, pH, time, and effect of catalysts; (ii) degradation efficiency of the processes when applied in combination with other advanced oxidation methods; (iii) key factors that affect the removal of PPCPs based on their properties. In addition, suggestions for future studies on advanced oxidation methods and their limitations were discussed. Overall, this review could aid in providing an in-depth understanding of the current research trends concerning PPCPs and advanced oxidation processes. • Removal of PPCPs using conventional wastewater treatment techniques is difficult. • Ultrasonication in combination with other AOP enhanced degradation efficiency. • Ionizing radiation in tune with biological treatment methods boosted degradation. • Electrochemical oxidation is better recommended as final step in water treatment.

Isolation and Identification of Resistant Bacteria from Petroleum Producing Vicinity by Gene Amplification and Sequencing

This investigation focuses on molecular identification of antibiotic resistant bacteria isolated from petroleum producing vicinity using 16S rRNA sequencing based technique. The bacterial 16s rRNA gene sequences were amplified using polymerase chain reaction, sequenced, characterized and compared by using primers which has been compared to national center for biotechnology information (NCBI) sequence database. The presence of the plasmid mediated antibiotic resistance determinants CTX-M and QNRB genes in the bacterial isolates were analyzed. A total of four bacterial isolates that were resistant to all the antibiotic agents used were identified molecularly. The BLAST results showed 100 % similarity and phylogenetic study indicated that the genes were evolutionarily related to Morganella morganii, Pseudomonas xiamenensis, Chryseobacterium cucumeris and Staphylococcus sp., respectively. The genes obtained were submitted to the NCBI gene bank and were assigned accession number; MN094330, MN094331, MN094332 and MN094333, respectively. CTX-M and QNRB genes were however absent in the bacterial isolates. The result identified some peculiar abilities of the bacterial isolates to be resistant to antibiotics and suggests a correlation with resistance and hydrocarbon utilizing bacteria. The level of resistance could be as a result of the disinfection process during wastewater treatment procedure or the same adaptive mechanisms possessed by the isolates to control the hydrocarbon concentration in their cell. The study also clearly indicates that these wastewaters, when discharged into the environment directly may pose a risk for the spread of antibiotic resistant bacteria.

Synthesis of magnetic nanoparticles-decorated halloysite nanotubes/poly([2-(acryloyloxy)ethyl]trimethylammonium chloride) hybrid nanoparticles for removal of Sunset Yellow from water

Magnetite nanoparticles (MNPs) were synthesized on the surface of halloysite nanotubes (HNTs) through co-precipitation approach and the achieved nanocomposites were employed as the support of surface polymerization of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) to obtain a hybrid adsorbent for removal of Sunset Yellow from wastewater. The resulting magnetic nanocomposite was assessed by several characterizations. The X-ray diffraction (XRD) pattern confirmed the synthesis of Fe3O4 MNPs on HNTs. The field emission scanning electron microscope (FESEM) images showed that spherical Fe3O4 MNPs were successfully synthesized and the energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of Fe element in nanocomposite structure. The solid adsorbent was prepared by the aid of the magnetic HNTs as the support. The vibrating sample magnetometer (VSM) was employed for assessment of the magnetic properties of the magnetic HNTs and the solid polymeric adsorbent. The Freundlich isotherm model was fitted the experimented data better than Langmuir isotherm model, indicating the multi-layer adsorption of the dye to the polymeric adsorbent. The polymeric adsorbent had facile elution procedure by the aid of NaCl solution of 1 M. The prepared adsorbent showed fast separation kinetic, reaching equilibrium in about 15 min. and high absorption capacity of 33.8 µmol/g at room temperature, which made this adsorbent a good candidate for industrial wastewater treatment procedures.

Water efficiency and safe re-use of different grades of water - Topical issues for the pharmaceutical industry

The pharmaceutical industry is a highly water-dependent economic sector and requires different degrees of water purity. The study presents an overview of the current water quality requirements, as well as limitations and safety considerations for water re-use in pharmaceutical manufacturing. Several principles for implementing circular economy elements into pharmaceutical wastewater treatment procedures are described: the use of recovered solvents as an easily degradable carbon source for the denitrification process, the use of phosphorus-containing wastewater as a nutrient source for activated sludge microorganisms, the use of inorganic acids and bases for pH control in wastewater treatment processes, and the use of Al3+ containing wastewater as a coagulant. The case study indicates that specific wastewater streams can be reused as secondary materials if the chemical composition of wastewater from pharmaceutical batch processing is well constrained and separate collection is ensured.

Insights into real industrial wastewater treatment by Fenton's oxidation in gas bubbling reactors

In the present study, bubbling reactors (BRs) were chosen to design a new procedure for real industrial wastewater (WW) treatment by Fenton's oxidation. The process was carried out in BRs under batch mode for the treatment of a WW with a high organic load (chemical oxygen demand (COD) above 7000 mgO2/L), being the efficient mixing of the liquid phase ensured by the gas bubbling. The parameters that influenced the WW treatment (i.e., H2O2 and Fe2+ concentration, and initial pH) were optimized in a smaller BR (0.5 L volumetric capacity); the maximum oxidation efficiency (dissolved organic carbon (DOC) removal = 52% and COD removal = 83% after 60 min) was reached under the following conditions: Qair = 1.0 L/min (measured at room temperature and atmospheric pressure), [H2O2] = 22.5 g/L, [Fe2+] = 0.75 g/L, and pH = 4.6 – original WW pH. It was not detected any significant effect in the process efficiency of the air flow rate and gas phase composition (i.e., N2, and air), but when the process was performed with continuous O2 bubbling an increase in the DOC removal (from 43% to 53%) was observed after 5 min of oxidation. Even so, the high costs discourage the use of pure oxygen streams in real WWTPs. To understand the dynamics of the process, the continuous air bubbling was compared to another mixing mode (mechanical stirring), and similar mineralization was achieved, proving the feasibility of Fenton's process in a BR. In addition, the gas bubbling proved to be more efficient in terms of heat dissipation during the treatment, decreasing temperature profiles along the oxidation of heavily charged real effluents. An effective scale-up with a bubble column reactor with a higher volumetric capacity by a factor of almost one order of magnitude was also proved, providing similar mineralization. The final effluent was non-toxic and more biodegradable.

Микробное сообщество в биодеградации нефтехимических отходов: метаболический потенциал, биоразнообразие и динамика

The metabolic potential of microorganisms plays an important role in the biodegradation of petrochemical waste. The characteristics of the microbial community involved in industrial wastewater treatment have been reviewed in many studies. Within this review, a complete understanding was provided about the characteristics of microorganisms such as bacteria, yeast, micromycetes, and the role of enzymes in the biodegradation process. Data on the structure of the microbial community and the metabolic potential of individual strains are promising for improving the procedure for preliminary wastewater treatment with an increase in the spectrum of strains that can degrade more toxic and resistant xenobiotics. Deciphering the structure of the microbial community is the key to create a rationally and functionally stable purification system.

Hospital wastewater treatment reduces NDM-positive bacteria being discharged into water bodies.

New Delhi metallo-β-lactamase-1 (NDM-1) is a novel type of metallo-β-lactamase (MBL) associated with Enterobacteriaceaeconstitutes an important growing public health threat. The present study aims to characterize the NDM-1 producing Gram-negative bacteria (GNB) from the effluents of two tertiary care hospitals in Mangalore, South India and to profile their antibiotic resistance pattern. A total of 134 GNB were isolated from 30 hospital wastewater samples (treated and untreated) and analyzed. High-level resistance among untreated effluent sample was found toward nalidixic acid (74.52%), followed by cefotaxime (72.64%) and ampicillin (66.03%). Among the treated effluent isolates, the high resistance was found toward ampicillin (85.71%) followed by cefotaxime (85.71%) and piperacillin-tazobactam (53.57%). From untreated effluent isolates, 9 were NDM-1 positive by PCR; no isolates from treated effluent samples harbored blaNDM-1 . Untreated hospital wastewater is found to be important reservoirs of antibiotic-resistant bacteria carrying blaNDM-1 , and the presence of such bacteria in the effluents is a matter of great concern because they can contribute the antibiotic resistance to the natural environment. However, the absence of NDM in treated effluents emphasizes the importance of effluent treatment in reducing the dissemination of antibiotic-resistant bacteria. PRACTITIONER POINTS: Hospital wastewater is the important reservoir of antibiotic-resistant bacteria especially metallo-β-lactamase producers (NDM-1). Wastewater treatment procedures in hospitals reduce the NDM isolates in the treated effluent. Thereby reduces the risk of resistance spread in the environment.

Reusability of Fe-modified MMT nanomembranes and the retrieval of the adsorbed mercury metal

Determining the applicability of a wastewater treatment procedure is dependent on its efficiency and cost-effectivity. The main objective of this study is to establish the reusability of Fe-modified MMT nanomembrane when utilized as adsorbent material for wastewaters containing mercury in complex with cyanide in aqueous solutions. Three cycles of adsorption-elution runs were done on the nanomembranes and the mercury (Hg) concentrations in the wastewaters (initial, after adsorption, after elution) were analyzed using HD XRF. Results showed that there was no substantial difference in the adsorption efficiencies for the first two (2) cycles (37.61% and 35.69%). Using 0.01M acetic acid as eluate, the nanomembranes were observed to be reusable twice before the nanomembranes become extensively degraded. In addition, precipitation was employed to retrieve the Hg from the eluates. One (1) g as-received and grinded (150–500μm) sodium thiosulfate (Na2S2O3) precipitants were used and it was established that, after 24 h, the precipitant with finer particle sizes was able to retrieve higher amounts of Hg (as-received:59% vs grinded:87.27%). Moreover, increasing the amount of the grinded Na2S2O3 to 5g resulted to better Hg recovery (89.47%). Further analysis on the derived precipitates also confirmed the presence of Hg (19.90ppm for red precipitates; 24.73ppm for black precipitates).

Photocatalysis and biodegradation of pharmaceuticals in wastewater: effect of abiotic and biotic factors

Pharmaceuticals (PhACs) are a class of emerging contaminants of global concern due to their ubiquitous nature, persistence and capability of affecting humans and aquatic lives negatively even at very low concentrations. Conventional wastewater treatment procedures are generally inadequate for removing these contaminants. Photocatalysis, an advance oxidation process (AOP), has been widely used in eliminating PhACs from wastewater. This is due to its low operational cost compared to other AOPs. However, the problem of complete mineralization of PhACs by photocatalysis remains a challenge. In this review, we discussed photocatalysis, biodegradation and mechanisms of action for the degradation of PhACs in wastewaters. The application of a combined photocatalytic biodegradation systems for the degradation of PhACs in wastewater was also presented. It is worthy of note that several operating parameters such as the biotic and abiotic factors are pivotal to an efficient photocatalytic and biodegradation treatment systems. Therefore, an integrated photocatalysis/biodegradation system is essential to achieving a complete mineralization of PhACs; other advantages of this treatment technique include low energy cost, effective degradation process, generation of non-toxic by-product and self-sustenance energy generation.

The performance of biological and tertiary wastewater treatment procedures for rotaviruses A removal.

Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading enteric viruses, the Rotavirus A (RVA) detection in wastewater appeared to be a novel approach to monitor the emergence of these viruses in some countries where the viral gastroenteritis surveillance is almost absent such as in Tunisia. The RVA detection and quantification in an industrial sewage purification plant of Charguia I (Tunis, Tunisia) were achieved to evaluate the performance of activated sludge procedures coupled to a macrofiltration monolamp ultraviolet irradiation type C (UV-C254) disinfection reactor. This UV-C254 system was preceded by a fiberglass cartridge filter system with an average porosity of 45 μm to clarify the water and thus increase its UV transmittance. A total of 140 composite sewage samples was collected from this line of treatment and analyzed for RVA detection. The detection and the viral load quantification of RVA were performed using real-time reverse transcription polymerase chain reaction (RT-PCR). The virological results showed in general that RVA were detected at high frequency of 98% (137/140). In fact, the RVA detection rates at the exit of the two studied wastewater treatment were about 100% at the exit of the activated sludge procedure. It means that all wastewater sampled at this last step of treatment was positive for RVA detection. On the other hand, 92.5% of the wastewater samples taken at the exit of the monolamp UV-C254 reactor were positive for the RVA. However, the RVA quantification results expressed as viral load showed a significant reduction in the means of RVA viral loads at the exit of the biological activated sludge procedure and the tertiary UV-C254 treatment, showing in general an improved treated wastewater virological quality. Therefore, the RVA load removal rates recorded at the two successive stages of treatment, the activated sludge and the UV-C254 treatment, were around 85% and 73%, respectively, as compared to the one with 100% registered for the raw wastewater. In addition, good physical-chemical and bacteriological qualities of the treated sewage were found at the exit of the two considered wastewater treatment procedures. The present investigation represents the first Tunisian environmental report showing the good effectiveness and performance of the biological and the tertiary treatments for RVA removal. Therefore, an improved and an optimized tertiary disinfection treatment was needed since it could be a good means for getting better viral water quality and for minimizing the transmission and dissemination of human infectious viral diseases.

Efficiency assessment of pollutants discharged in urban wastewater treatment: Evidence from 68 key cities in China

Pollutant removal is a critical procedure for wastewater treatment because it directly determines the effectiveness of wastewater treatment and water conservation. Therefore, assessing pollutant discharge efficiency in wastewater treatment is imperative. In this study, an environmental production technology with a non-radial data envelopment analysis model is developed to examine the discharge efficiency and reduction potential of pollutants in wastewater treatment in 68 key cities by considering the disparity of city scales. By comparing discharge efficiency and reduction targets released in the 12th Five-Year Plan, this study identified the key areas that need to be addressed for wastewater treatment with regard to different city types. Results showed that chemical oxygen demand (COD) and ammonia nitrogen (AN) have similar discharge efficiency values, mainly ranging from 0.5 to 0.7. More specifically, the discharge efficiency of COD is comparatively lower than that of AN. City size generated a positive impact on efficiency improvement. Centralized treatment system is beneficial for achieving the scale effect in wastewater treatment. An examination of the progress of reduction target systems indicated that AN is comparatively inferior in reduction completion. Apart from the technical barriers, this fact is highly related to the willingness and power of the local government. Cities should identify the key areas that need to be addressed and adopt the corresponding reduction strategies by referring to their scales. The findings of this study can facilitate the inclusion of pollution mitigation in the urban agenda, thereby fostering an effective wastewater treatment process and creating a benchmarking framework for governing wastewater pollution.

Synthesis of Optimized Molecularly Imprinted Polymers for the Isolation and Detection of Antidepressants via HPLC.

Antidepressants such as amitryptiline and fluoxetine are on the list of modern essential medicines of the World Health Organization. However, there are growing concerns regarding the ecological impact of these pharmaceuticals, leading to a great need to improve current wastewater treatment procedures. In this contribution, we will report on the use of molecularly imprinted polymers (MIPs) for the extraction of antidepressants in water samples. MIPs were developed for fluoxetine and duloxetine, antidepressants belonging to the class of selective serotonin reuptake inhibitors (SSRIs). The binding capacity of these microparticles was evaluated using ultraviolet–visible (UV–Vis) spectroscopy. A new high-performance liquid chromatography (HPLC) procedure coupled to UV detection was developed, which enabled the study of mixtures of fluoxetine and duloxetine with other nitrogen-containing compounds. These results indicate that it is possible to selectively extract SSRIs from complex samples. Therefore, these versatile polymers are a promising analytical tool for the clean-up of water samples, which will benefit aquatic life and reduce the ecological impact of pharmaceuticals.

Identification of Physical, Morphological and Chemical Particularities of Mixed Microalgae - Bacteria Granules

The growth of population has been linked with the increase usage of chemical compounds design for domestic and industrial use. At its turn, the increased amount of the chemical compound puts an enhanced stress on the environment. In such scenario, the waste management, including the wastewater treatment strategies have become an important part for the environmental protection. Unfortunately, the wastewater treatment procedures have several components which could be improved. Among them aeration process and biomass sedimentation have been the most stringent to tackle, since the aeration alone consume more than 60% from wastewater treatment energy cost. In this study, we proposed a new microalgae-bacteria activated sludge granule which could be an economical and technological solution to the above mentioned issues such as aeration and sedimentation. Moreover, during this study we characterized the physical, morphological and chemical characteristic of the newly formed granules by advances techniques such as electronic and correlative microscopy.

Detection of Sapoviruses in two biological lines of Tunisian hospital wastewater treatment

ABSTRACTThe efficiency of rotating biodisks and natural oxidizing lagoon procedures is investigated at a Tunisian semi-industrial pilot plant, El Menzeh I, where the wastewater is mainly provided by three different neighbouring hospital clinics. Throughout 2011, 102 wastewater samples were collected from the two mentioned wastewater treatment procedures. Results showed that the Sapovirus (SaV) frequency was approximately 29.4% using the real-time reverse transcription polymerase chain reaction (RT-PCR) technique, and about 16.6% using the conventional RT-PCR. Also, the SaV genogroups and genotypes were identified and genotyping revealed that all of the four Tunisian SaV strains obtained belonged to the two genogroups GIV.1 and GGI.3. In addition, two new genotypes, D and C, were detected. A moderate decrease in the SaV frequencies was observed at the exit of the two treatment processes and the SaV removal rate was around 90% in the natural oxidizing lagoons and 94% in the rotating biodisks procedure showing the temperate sensitivity of these viruses to the implemented biological wastewater. Therefore, an urgent disinfection process should be implemented downstream of the two biological treatment procedures for safe release of treated effluent in the different natural environments.Abbreviations: NoV: Noroviruses; SaV: Sapoviruses; EC: Electrical Conductivity; COD: Chemical Oxygen Demand; BOD5: Biological Oxygen Demand; SS: Suspended Solids; NH4-N: Ammonium Nitrogen; P-PO4: Ortho-Phosphate; AlCl3: aluminum chloride

Feasibility removal of BOD5, COD, and ammonium by using Gambusia fish and Phragmites australis in H-SSF wetland

Today, there is a wide range of wastewater treatment procedures, but most of them have major problems, such as high construction costs, high energy consumption, complex operation, and the need for sludge treatment and disposal, and requirement to use high technology for treatment. The main objective of this study was to evaluate the effectiveness of horizontal subsurface flow constructed wetlands (H-SSF CWs) by Gambusia fish and Phragmites australis (plant) for municipal wastewater treatment. This study focused on the removal of BOD5, COD, and ammonium. The wastewater was used as the raw input effluent to the Shahid Mahallati Wastewater Treatment Plant in Tehran, Iran. The pilot used included five 120-liter tanks. In tank 1, coded 2-A, the plant of P. australis was planted and from tank 4 used as a control sample (without P. australis). In the remaining two tanks, tank 2-B and 3, Gambusia fish were placed. At the beginning of the study, the dilution of the input effluent was done for the adaptation. The removal efficiency of BOD5 in the tanks of 1, 2, 3, and 4 was 91.83%, 91.97%, 4.12%, and 71.16%, respectively. The removal efficiency has increased in all tanks in the summer compared to spring. The results of the study showed that the maximum removal efficiency was observed in tank 2 due to the presence of P. australis–Gambusia fish. The mean concentration of ammonium in the spring and summer was 14.37 mg/l and 19.7 mg/l, respectively. The removal efficiency of NH4+ in the tanks of 1, 2, 3, and 4 was 36%, 11.38%, and 4.56%, respectively. So, the NH4+ removal efficiency has increased in all constructed wetlands in the summer compared to spring. Based on the results, H-SSF CWs can be considered as a good alternative for wastewater treatment in small communities.

Chlorination of 5-fluorouracil: Reaction mechanism and ecotoxicity assessment of chlorinated products

What happens to drugs in the chlorinating environment? Degradation products may vary in pharmacological profiles and in ecotoxicity potentials compared to the parent compound. This study combines synthesis, NMR spectroscopy, quantum chemical calculations, and toxicity experiments on Daphnia magna to investigate chemical fate of antineoplastic drug 5-fluorouracil (5-FU) in chlorinated environment, which is common in waste-water treatment procedures, but also endogenous in activated neutrophils. A reduction of toxicity (EC50 after 48 h is 50% higher than for the parent 5-FU) was observed after the first chlorination step, in which a chlorohydrin 5-chloro-5-fluoro-6-hydroxy-5,6-dihydrouracil was formed. Further chlorination leads to N-chlorinated intermediate, that undergoes the pyrimidine ring opening reaction. The final product, 2-chloro-2-fluoro-3,3-dihydroxypropanoic acid was obtained after the loss of the chlorinated urea fragment. This is the most potent compound in the reaction sequence, with toxicity parameter EC50, after 48 h, more than twice lower compared to the parent 5-FU. Clearly, the contact time between chlorinating species and degradation products provide different ecotoxicological properties of reaction mixtures. Interplay between experimental and theoretical procedures, to properly describe reaction pathways and provide more information on toxicity profiles, is a way forward in environmental science research.

Flocculation efficiency of the Sinorhizobium meliloti 1021 exopolysaccharide relative to mineral oxide suspensions – A preliminary study for wastewater treatment

Abstract The main aim of the study was to examine the Sinorhizobium meliloti1021 exopolysaccharide (EPS) flocculation efficiency relative to mineral oxide suspensions and verify if EPS can be used in the wastewater treatment procedure. The paper compares the EPS adsorption influence on the stability of various mineral oxide suspensions (chromium(III) oxide, silica, zirconia). Moreover, it indicates the solid whose aqueous suspension is the most destabilized in the EPS presence. The selected adsorbents have different surface properties. They are characterized by different pHpzc (zero surface charge) and pHiep (isoelectric) points. The highest adsorption amount was observed on the chromium(III) oxide surface. It resulted in the greatest changes in the particle zeta potential and surface charge density. The exopolysaccharide addition affects the stability of all mineral oxide suspensions. The most significant changes were observed for chromium(III) oxide and zirconia at pH 9. Under these conditions there is a bridging flocculation in the system, so the S. meliloti exopolysaccharide can be regarded as a potential flocculant related to these solids. In turn, the silica suspension stability changes insignificantly in the EPS presence.