Biodegradation of wastewater organic contaminants using Serratia sp. ISTVKR1 isolated from sewage sludge

Green Assessment of Analytical Procedures for the Determination of Pharmaceuticals in Sewage Sludge and Soil

The main difficulties when analyzing pharmaceutically active compounds (PhACs) in solid environmental samples is the complexity of the samples and the low concentration levels of such pollutants. Most efforts are focused in achieving good analytical performance parameters such as high recoveries or low detection limits without considering if the methods are environmentally friendly. In this work, the main tools proposed for assessing the greenness of analytical methodologies (Analytical Eco-scale, Green Analytical Procedure Index (GAPI), and Analytical GREEnness metric (AGREE)) have been applied to nine analytical procedures that include recent important analytical tendencies. The three metrics identified the paper spray ionization method as the greenest procedure since it used untreated samples for direct mass spectrometry analysis. Using Analytical Eco-scale, most of the evaluated procedures were rated as "acceptable green". However, the use of internal standards resulted key in the environmental impact of the method which provided contradictory results versus other metrics. GAPI found greenness similarities between most of selected methods, hindering a greenness classification. AGREE allowed the weighting of each evaluation criterion providing a greenness ranking. The application of each metric detecting their weaknesses and strengths was discussed. The incorporation of validation analytical features in greenness metrics was a gap revealed.

Utilization of Waste Biomaterial as an Efficient and Eco-Friendly Adsorbent for Solid-Phase Extraction of Pantoprazole Contaminants in Wastewater

The objective of this analysis is to establish the potential of biodegradable agro-industrial waste materials as biosorbents in the solid-phase extraction (SPE) technique for sample preparation. In this regard, waste coffee husk (CH) powder was collected, washed, treated chemically, characterized, and applied as an SPE adsorbent to extract pantoprazole from the wastewater samples. Sample detection was accomplished using the UPLC-MS/MS system. The positive mode of electrospray ionization was exploited for the ionization of the sample, and quantification of the target analyte was performed by the multiple reaction monitoring modes. The precursor to product ion transition of 384.02→1380.05 and 384.02→200.05 was used as qualifiers and quantifiers, respectively. Optimization of the particle size, adsorbent dose, and contact time were evaluated to select the best combination of features. The efficiency and regeneration capability of the CH were compared with respect to a commercially available silica-based C18 SPE adsorbent, and it was found that CH possessed comparable (~50%) extraction, as well as regeneration capacity (~95%). The developed biosorbent was applied in a wastewater sample spiked with the target analyte and recovery studies were performed, which found a range of 93.0 to 102.0% with a %RSD of 3.72 to 12.7%. Thus, CH can be exploited as a ‘greener’ replacement for the commercially available adsorbents for the extraction/retention of active pharmaceutical ingredients present in water/wastewater samples.

Lurgi-Thyssen dust catalytic thermal desorption remediation of di-(2-ethylhexyl) phthalate contaminated soils

Fe2O3-assisted pyrolysis has been demonstrated to be a cost-effective thermal desorption (TD) technology. Lurgi-Thyssen dust (LTD) is a type of steel slag waste that contains a large amount of Fe2O3. In this study, to reduce energy consumption, LTD was added to contaminated soil to evaluate the feasibility of enhancing the TD removal efficiency of di-(2-ethylhexyl) phthalate (DEHP). The DEHP removal rate increased by 22.39% after adding 2% LTD at 200 °C for 20 min. Because of the catalytic pyrolysis of LTD, DEHP was pyrolyzed to form three types of short-chain esters: mono-(2-ethylhexyl) phthalate (MEHP), di (2-methylbutyl) ester, and methyl 2-ethylhexyl phthalate. The pyrolysis products of DEHP were less toxic and did not affect soil reuse. When the DEHP removal rate was 87.10%, LTD addition decreased the temperature and residence time of TD and alleviated the effect of TD on the soil physicochemical properties. Additionally, the desorption of DEHP from soil fitted the pseudo-second-order kinetic model well. Thus, the addition of LTD to contaminated soil enhanced the efficiency of TD remediation. Moreover, this study could provide a practical and economical strategy for LTD reuse.

A systematic review on chlorine tolerance among bacteria and standardization of their assessment protocol in wastewater

Though chlorine is a cost-effective disinfectant for water and wastewaters, the bacteria surviving after chlorination pose serious public health and environmental problems. This review critically assesses the mechanism of chlorine disinfection as described by various researchers; factors affecting chlorination efficacy; and the re-growth potential of microbial contaminations in treated wastewater post chlorination to arrive at meaningful doses for ensuring health safety. Literature analysis shows procedural inconsistencies in the assessment of chlorine tolerant bacteria, making it extremely difficult to compare the tolerance characteristics of different reported tolerant bacteria. A comparison of logarithmic reduction after chlorination and the concentration-time values for prominent pathogens led to the generation of a standard protocol for the assessment of chlorine tolerance. The factors that need to be critically monitored include applied chlorine doses, contact time, determination of chlorine demands of the medium, and the consideration of bacterial counts immediately after chlorination and in post chlorinated samples (regrowth). The protocol devised here appropriately assesses the chlorine-tolerant bacteria and urges the scientific community to report the regrowth characteristics as well. This would increase the confidence in data interpretation that can provide a better understanding of chlorine tolerance in bacteria and aid in formulating strategies for effective chlorination.

The risk of transmitting antibiotic resistance through endophytic bacteria

Antibiotic resistance is a global human health threat distributed across humans, animals, plants, and the environment. Under the One-Health concept (humans, animals, and environment), the contamination of water bodies and soil by antibiotic-resistant bacteria cannot be dissociated from its potential transmission to humans. Edible plants can be colonized by a vast diversity of bacteria, representing an important link between the environment and humans in the One-Health triad. Based on multiple examples of bacterial groups that comprise endophytes reported in edible plants, and that have close phylogenetic proximity with human opportunistic pathogens, we argue that plants exposed to human-derived biological contamination may represent a path of transmission of antibiotic resistance to humans.

Nitrification and denitrification processes for mitigation of nitrous oxide from waste water treatment plants for biovalorization: Challenges and opportunities

Nitrous oxide (N₂O) is a potent greenhouse gas. Even though its emissions is much lesser than CO₂ but its global warming potential (GWP) is 298 times more than CO₂. N₂O emissions from wastewater treatment plants was caused due to incomplete nitrification or incomplete denitrification catalyzed by ammonia-oxidizing bacteria and heterotrophic denitrifiers. Low dissolved oxygen, high nitrite accumulation, change in optimal pH or temperature, fluctuation in C/N ratio, short solid retention time and non-availability of Cu ions were responsible for higher N₂O leakage. Regulation of enzyme metabolic pathways involved in N₂O production and reduction has also been reviewed. Sequential bioreactors, bioscrubbers, membrane biofilters usage have helped microbial nitrification-denitrification processes in succumbing N₂O production in wastewater treatment plants. Reduction of N₂O negativity has been studied through its valorization for the formation of value added products such as biopolymers has led to biorefinery approaches as an upcoming mitigation strategy.

Genome Sequence of a Heterotrophic Nitrifier and Aerobic Denitrifier, Paracoccus denitrificans Strain ISTOD1, Isolated from Wastewater

We report here the draft genome sequence of Paracoccus denitrificans strain ISTOD1 of 4.9 Mb, isolated from wastewater. It has been identified as a heterotrophic nitrifying and aerobic denitrifying bacterium. Genomic analysis revealed genes related to nitrogen and phosphorus removal, showing that the strain holds potential for bioremediation and biorefinery uses.

Ecotoxicological and microbiological assessment of sewage sludge associated with sugarcane bagasse

Sewage sludge (SS) obtained after sewage treatment process may contain several toxic substances. Bioremediation can decrease the toxicity of the sludge, mainly when it is associated with stimulant agents, such as sugarcane bagasse (B). Samples of pure SS (SSP); SS+B; SS+Soil; and SS+B+Soil were bioremediated for 1, 3, and 6 months (T1, T2, and T3, respectively). After each period, the cytotoxic, genotoxic, and mutagenic potentials of the solid samples and their respective aqueous extracts (aqueous eluate and percolate water) were evaluated by the Allium cepa test. A microbiological analysis of the samples was also performed after each period tested. All solid samples of SS+B (in T1, T2, and T3) and the solid sample of SSP (treatment T3) showed a significant decrease of cell division (cytotoxic effects). The aqueous eluate extracts of SS+B (T1 and T3) and SSP (T2 and T3) induced cytotoxic effect. The solid sample of SS+B (T2 and T3) and aqueous extracts of SSP (T1) were genotoxic, indicating a harmful effect of SS on A. cepa, even after 6 months of bioremediation. There was an alternation in the microbial community both in diversity and in abundance, with the predominance of nonfermenting gram-negative bacilli. The tested bioremediation periods were not sufficient for the complete detoxification of SS, and the use of B did not seem to contribute to the degradation of the pollutants to inert compounds. These data emphasize that a specific relationship should exist between the sludge characteristic and the biostimulating agent used to promote a more efficient bioremediation. These results suggest the necessity to study longer periods of biodegradation and the use of other decomposing agents for greater safety and sustainability for the agricultural use of this residue.

Analysis and optimization of process parameters for production of polyhydroxyalkanoates along with wastewater treatment by Serratia sp. ISTVKR1

A previously reported biodegrading bacterial strain Serratia sp. ISTVKR1 was studied for polyhydroxyalkanoate (PHA) production along with wastewater contaminant removal. Nile red fluorescence, GC-MS, FT-IR, NMR and TEM confirmed the accumulation of homopolymer poly-3-hydroxyvalerate (PHV) within the bacterial cells. Analysis of culture after 72h of bacterial treatment showed maximum COD removal (8.4-fold), non-detection of organic contaminants such as 1H-Cyclopropa [a] naphthalene (R.T.=10.12) using GC-MS and increased proportion of elements like Cr, Mn, Fe, Ni, Cu, Cd and Pb in the bacterial cell pellets by SEM-EDX analysis. Optimization of process parameters for enhanced PHA production along with wastewater treatment done using Response Surface Methodology (RSM) showed 5% and 0.74% increase in the PHA production (0.3368±0.13gL^-1) and % COD reduction (88.93±2.41) of wastewater, respectively. The study, thus established the production of PHA along with wastewater contaminant removal by Serratia sp. ISTVKR1.

Environmental risk assessment of effluents as a whole emerging contaminant: Efficiency of alternative tertiary treatments for wastewater depuration

Emerging contaminants (ECs) and regulated compounds (RCs) from three different WWTP effluents were measured in the current study. The efficiency of two tertiary treatments, Photobiotreatment (PhtBio) and Multi-Barrier Treatment (MBT), for removing contaminants was determined. Results indicated different percentages of removal depending on the treatment and the origin of the effluent. Risk Quotients (RQs) were determined for different species of algae, Daphnia, and fish. RQ results revealed diverse risk values depending on the bioindicator species. Tonalide, galaxolide (fragrances), and ofloxacin (antibiotic) were the most persistent and harmful substances in tested effluents. "Negligible risk" category was reached since a wide diversity of ECs were removed by MBT with high removal percentages. Contrarily, PhtBio was effective only in the depuration of certain chemical compounds, and its efficiency depended on the composition of the raw effluent.

Metabolic and Co-Metabolic Transformation of Diclofenac by Enterobacter hormaechei D15 Isolated from Activated Sludge

The presence of non-steroidal anti-inflammatory drugs, such as diclofenac (DCF), in the environment, is an emerging problem due to their harmful effects on non-target organisms, even at low concentrations. We studied the biodegradation of DCF by the strain D15 of Enterobacter hormaechei. The strain was isolated from an activated sludge, and identified as E. hormaechei based on its physiological characteristics and its 16 S RNA sequence. Using HPTLC and GC-MS methods, we demonstrated that this strain metabolized DCF at an elimination rate of 52.8%. In the presence of an external carbon source (glucose), the elimination rate increased to approximately 82%. GC-MS analysis detected and identified one metabolite as 1-(2,6-dichlorophenyl)-1,3-dihydro-2H-indol-2-one; it was produced as a consequence of dehydration and lactam formation reactions.

Study of optimization of wastewater contaminant removal along with extracellular polymeric substances (EPS) production by a thermotolerant Bacillus sp. ISTVK1 isolated from heat shocked sewage sludge

The present work involved study of wastewater contaminant removal along with EPS production by a thermotolerant bacterium Bacillus sp. ISTVK1, isolated from heat shocked sewage sludge. EPS production in basal and mineral medium containing 50% filter sterilized wastewater and 0.5% sucrose was found to be 0.83±0.12gL(-1) and 0.31±0.10gL(-1) culture, respectively. GC-MS analysis of EPS revealed the presence of β-d-glucose, α-d-galactose and β-d-arabinose. FT-IR spectrum confirmed the presence carbohydrates. Box-Behnken design was used to optimize process parameters for enhanced EPS production along with % COD reduction of wastewater. The optimised conditions when used in a 1.5L bioreactor showed EPS production of 1.67±0.06gL(-1) culture and 93.0±0.21 % COD removal.