Wastewater Treatment Techniques Research Articles

Wastewater quality evaluation in terms of wastewater quality index using hybrid constructed wetland for treatment of dairy and municipal wastewater.

The world's most pressing problem is water shortage, which is made worse by fast industrialization and urbanization, especially in places like India where untreated effluent presents serious threats to human health and the environment. In order to treat dairy and municipal wastewater, this study assesses the efficacy of a two-stage hybrid constructed wetland (CW) system. The WWQI is the primary focus of this evaluation over a range of mixing ratios. Before and after treatment, many physicochemical parameters were examined, including pH, total suspended solids (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total phosphorus (TP), ammonia nitrogen ( ), and nitrate nitrogen ( ). The hybrid CWs system dramatically lowers pollutant concentrations, according to the results, with combinations containing higher amounts of MWW showing the best results. The WWQI values, which change from "unfit for any uses" in untreated DWW to "excellent" quality in treated MWW, show these advancements. The results highlight the potential of hybrid CWs as an effective and sustainable wastewater treatment method, especially when it comes to maximizing the proportion of dairy to municipal wastewater. This study adds to our knowledge of efficient wastewater treatment techniques and highlights the significance of incorporating eco-friendly technologies to tackle water scarcity issues. PRACTITIONER POINTS: Hybrid Constructed Wetlands (HCWs) are effective in removing TSS, BOD, COD, TP, ammonia nitrogen, and nitrate nitrogen from dairy and municipal wastewater. On the basis of HCWs performance determine the Wastewater Quality Index (WWQI) for four different ratio proportions of dairy and municipal wastewater. This index is more useful for water quality status determination and treated water reuse for various purposes. This also benefits sustainable treatment technology and contributes to achieving SDGs.

Assessing the Efficiency of Phragmites australis in Wastewater Treatment as a Natural Approach to Water Quality Improvement

The Oued Zénati, a vital waterway in Algeria, faces severe pollution from urban discharges, hospital wastewater, and agricultural activities, threatening both the ecosystem and public health. This pollution is characterized by high nutrient levels, suspended solids, and fecal contamination indicators, jeopardizing biodiversity and human well-being. To explore natural restoration solutions, this study assessed the purification potential of reeds (Phragmites australis) found in the Oued Zénati riverbed. Water quality was analyzed at three sites: a non-polluted control site (S1), a wastewater discharge area (S2), and a reed-dense area (S3). Results revealed a significant deterioration in water quality at site S2, with high concentrations of nutrients, suspended solids (SS), and fecal contamination indicators. However, a notable improvement in water quality was observed at site S3, downstream of the reed-dense area, with reductions in fecal coliforms (68.5%), fecal streptococci (92.3%), and phosphates (40.3%), and increased levels of dissolved oxygen (DO). These findings suggest that phytoremediation using P. australis could offer a cost-effective, sustainable, and eco-friendly solution for restoring the Oued Zénati. This study recommends establishing phragmifiltration stations, developing artificial wetlands, and enhancing sanitation systems, including hospital wastewater treatment. Public awareness campaigns promoting water and environmental protection are crucial for long-term success. This phytoremediation approach offers economic, ecological, and aesthetic advantages over conventional wastewater treatment techniques.

Tandem Active Sites in Cu/Mo‐WO3 Electrocatalysts for Efficient Electrocatalytic Nitrate Reduction to Ammonia

AbstractElectrocatalytic NO3− reduction to NH3 is a promising technique for both ammonia synthesis and nitrate wastewater treatment. However, this conversion involves tandem processes of H2O dissociation and NO3− hydrogenation, leading to inferior NH3 Faraday efficiency (FE) and yield rate. Herein, a tandem catalyst by anchoring atomically dispersed Cu species on Mo‐doped WO3 (Cu5/Mo0.6‐WO3) for the NO3RR is constructed, which achieves a superior FENH3 of 98.6% and a yield rate of 26.25 mg h−1 mgcat−1 at −0.7 V (vs RHE) in alkaline media, greatly exceeding the performance of Mo0.6‐WO3 and Cu5/WO3 counterparts. Systematic electrochemical measurement results reveal that the promoted activation of NO3− on Cu sites, accompanying accelerated water dissociation producing active hydrogens on Mo sites, are responsible for this superior performance. In situ infrared spectroscopy and theoretical calculation further demonstrate that atomically dispersed Cu sites accelerate the conversion of NO3− to NO2−, and the Mo dopant activates adjacent Cu sites, resulting in the decreased energy barrier of *NO2 to *NO and the stepwise hydrogenation processes, making the synthesis of NH3 thermodynamically favorable. This work demonstrates the critical role of tandem active sites at atomic level in enhancing the electrocatalytic NO3− reduction to NH3, paving a feasible avenue for developing high‐performance electrocatalysts.

Application of algae and zeolite in wastewater treatment: Effects on maize properties and soil fertility

ABSTRACT As a consequence of fresh water shortage, non-conventional water resources have become increasingly demandable in semi-arid and arid areas due to the increase in population and urbanization. In Egypt, the reuse of drainage water provides a demanding supplement to irrigation water. This research aims to present natural treatment process for drainage wastewater to be reused in irrigation to support water resources and water quality control. Two biological and chemical wastewater treatment techniques (Algae and Zeolite), under different conditions, were applied to allow the reuse of wastewater to be utilized in the agriculture of very economically important crop which is maize, and comparing the production and the chemical components of the crop with the one irrigated by fresh Nile water. Water, soil and plant analyses were performed. Zeolite was characterized by XRD, SEM and FTIR. Enzymes activities were assigned also (dehydrogenase, phosphatase and nitrogenase activities) and finally the statistical analysis was determined by CoStat software. The treated wastewater chemical and biological analyses showed much better results than El-Rahawy drain wastewater analyses. The plants growth parameters results showed the higher ones with plants subjected to the chemical and biological treatments. Protein and carbohydrate levels, which are the most important plant quality indicators, showed higher concentrations in the treated ones than that irrigated with Nile water. NPK concentration of both seeds and leaves also recorded better levels. The results of the enzymes activities in cases of T4, dehydrogenase, phosphatase, and nitrogenase enzyme activity were 127.66, 40.89, and 79.58, respectively, which increased when compared with control treated with Nile water which were (112.44, 28.4, and 41.39) for dehydrogenase, phosphatase and nitrogenase enzymes respectively.

Comparative analysis of hospital laboratory wastewater treatment techniques in Syrian Arab Republic

Background: Hospital wastewater poses a significant threat to human health due to the presence of difficult-to-degrade organic compounds, active pharmaceutical ingredients and multiple inorganic substances that can pollute water resources and ecosystems. Aim: To compare the effectiveness of different techniques for removing organic load from hospital laboratory wastewater in Aleppo, Syria. Methods: We treated wastewater samples from hospital laboratories at Aleppo University Hospital, Syria, using several techniques, including biological treatment with the rotating biological contactor, adsorption with Syrian natural clay, coagulation with aluminium sulphate, advanced oxidation with ultrasound, and a combined treatment using natural clay and ultrasound. We assessed the organic load removal efficiency for each technique under different conditions. Results: The most effective technique was the combination of natural clay and ultrasound. Applying natural clay at a concentration of 1 g/L of wastewater along with ultrasound at 40 kHz for 30 minutes achieved chemical oxygen demand and biochemical oxygen demand values suitable for irrigation, in accordance with the Syrian standard. The chemical oxygen demand value decreased to 212 mg/L with 94% removal rate, and the biochemical oxygen demand value decreased to 82 mg/L with 87% removal rate. Conclusion: Based on our findings, techniques that combine different methods of hospital wastewater treatment, such as combining adsorption with advanced methods like ultrasound, are more effective than those that use single methods. Such techniques should be promoted.

Interface dependent electron shunting in graphene-integrated intimately coupled photocatalytic biodegradation.

Intimately coupled photocatalytic biodegradation (ICPB) has been recently developed as an efficient wastewater treatment technique, particularly for removing persistent organic pollutants. However, photocatalyst/biofilm interaction in terms of photoelectron transfer and its effect on the overall performance of ICPB has not been explored. To investigate these points, interface-engineered composites of bismuth vanadate and reduced graphene oxide with low degree (BiVO4/rGO-LC) and high degree of their contact (BiVO4/rGO-HC) were fabricated and applied for ICPB. As a result, the composites displayed interface-dependent optical, structural and charge carrier separation properties. The photoelectrochemical measurements confirmed the presence of photoelectron shunting between photocatalyst and biofilm, while the current density was higher (smaller Nyquist arc) for BiVO4/rGO-HC than BiVO4/rGO-LC and BiVO4 in ICPB protocol, confirming the crucial role of intimate interfacial contact for photoelectron shunting from BiVO4 to biofilm. Consequently, the presence of graphene and its interfacial quality dictated the photoelectron shunting between photocatalyst and biofilm, enhancing photoelectron-holes separation and achieving superior degradation rate of tetracycline hydrochloride for BiVO4/rGO-HC (0.035 h-1) compared to BiVO4/rGO-LC (0.0128 h-1) and BiVO4 (0.011 h-1) in ICPB protocol. The electrical energy per order required for removal of tetracycline hydrochloride in the ICPB protocol exhibited the lowest value for BiVO4/rGO-HC among the tested materials and treatment protocols. These results highlight the importance of photoelectron shunting in enhancing efficiency of ICPB by engineering graphene at the interface of photocatalyst and biofilm. This unveiled mechanism may serve as an excellent potential in designing energy-efficient ICPB systems targeting wastewater matrices.

Construction of piezoelectric fenton-like system over BaTiO3/α-FeOOH for highly efficient degradation of demethylchlortetracycline

Heterogeneous Fenton-like system is a promising technique for wastewater treatment, while Fe2+ regeneration limits its degradation efficiency. Piezoelectric materials can produce free electrons under mechanical stress. Based on this, a piezoelectric Fenton-like system coupling piezoelectric effect and Fenton-like reaction was proposed. Composite material BaTiO3/α-FeOOH was synthesized by sol–gel and hydrothermal method. Under ultrasonic vibration BaTiO3 continuously generated free electrons, which reduced Fe3+ to Fe2+ and realized Fe3+/Fe2+ cycle. The piezoelectric Fenton-like system based on BaTiO3/α-FeOOH was used to remove demethylchlortetracycline (DMCT) from water. The degradation ratio of DMCT can reach 100 % within 5 min, and the coupled system exhibited excellent adaptability and stability. Free radical capture and quantitative detection determined that •OH and •O2− were the main active oxygen species. A comprehensive catalytic mechanism was proposed and supported by energy band structure analysis, finite element method simulation, and Density Functional Theory (DFT) simulation calculations. The piezoelectric electrons generated by BaTiO3 were transfered to α-FeOOH to improve the Fe3+/Fe2+ cycle. In addition, the possible degradation mechanism of DMCT was proposed through Ultra Pressure Liquid Chromatography-Mass Spectrometry (UPLC-MS) measurement and DFT calculation, and the overall pollution toxicity of DMCT was assessed according to toxicity prediction. Overall, this work provided a new insight on coupling effect between piezoelectric effect and Fenton-like reaction.

Doped hydroxyapatite photocatalyst for efficient degradation of Methylene blue dye

Extensively increasing discharge of organic pollutants and industrial dyes in water necessitates the development of eco-friendly, cost-effective, and sustainable techniques for wastewater treatment. Here, we report the photocatalytic degradation activity of biocompatible and non-toxic copper-doped hydroxyapatite (Cu-HAp) against Methylene blue (MB) dye. A series of Cu-HAp samples were successfully synthesized using the coprecipitation method with varying concentrations of Cu dopant (0, 0.15 %, 0.35 %, 0.55 %, and 0.75 %) on a molar basis. Structural, morphological, and optical properties of Cu-HAp samples were characterized systematically. X-ray diffraction analysis confirmed the hexagonal structure of Cu-HAp. In addition, the EDS results confirmed the presence of Cu dopant in HAp samples. The optical bandgap of HAp decreased from 5.08 to 3.36 eV with increasing the concentration of Cu-dopant up to 0.75 mol%. We observed more than 80 % degradation efficiency for MB dye with 160 min of sunlight exposure. Moreover, the pseudo-first-order- rate constant increased from 0.00218 (HAp) to 0.00935 min−1 (0.75 % Cu-HAp). Our results showed the recyclability and stability of the Cu-HAp photocatalyst followed by four cycles of dye degradation testing. The current study highlights the potential of Cu-HAp to be used as a photocatalyst for wastewater treatment.

Sustainable Wastewater Treatment: Recent Progress in the use of Bio-Waste-Derived Adsorbents for Organic Dye Removal

There are serious health and environmental hazards associated with the growing amount of organic dyes in wastewater from sectors like food processing, leather, and textiles. These pollutants are frequently ineffectively removed by traditional wastewater treatment techniques. Adsorbents made from bio-waste have become a viable substitute because of their high removal efficiency, affordability, and sustainability. The adsorption of organic dyes is facilitated by the distinct surface chemistries of these adsorbents, which are made from a variety of biomass sources. Through synthesis and modification approaches, recent research has concentrated on enhancing these materials' adsorption capacity, selectivity, and overall performance. Adsorbents made from bio-waste have potential uses in pollutant degradation, nutrient recovery, and value addition in addition to dye removal. But issues like leaching and long-term stability need to be carefully thought out. This review highlights the recent advancements in the application of bio-waste-derived adsorbents for organic dye removal from wastewater, emphasizing their potential contributions to sustainable wastewater treatment and resource recovery.

Enhanced solar interfacial evaporation through lignin-polyaniline composite coatings on Balsa wood substrates

Solar interfacial evaporation employing wood-derived substrates is increasingly acknowledged as a viable desalination and wastewater treatment technique. This study presents an optimized method that enhances the efficiency of solar interfacial evaporation by applying a coating of lignin-polyaniline composites (EHL-PANI) onto balsa wood substrates. Initial assessments involved comparing evaporators made from various kinds of wood, identifying balsa wood-based photothermal evaporators as the most effective, with an evaporation rate of 1.63 kg·m−2·h−1 and an efficiency of 72.7 %. Photothermal properties were further improved through the chemical oxidation of enzymatic hydrolysis lignin (EHL) with polyaniline, producing a composite with notably high dispersion stability and uniform particle distribution. This modification resulted in reduced particle size and enhanced stability of the polyaniline, which is crucial for boosting photothermal activity. Additionally, the EHL-PANI composites demonstrated exceptional light absorption, exceeding 95 %, and significant photothermal conversion efficiency across a broad wavelength range, attributable to polyaniline's broadband light absorption characteristics. A prototype evaporator, featuring the EHL-PANI coated on a balsa wood substrate, was constructed to assess performance, achieving a water evaporation rate of 2.10 kg·m−2·h−1 and an efficiency of 80.7 % under solar illumination of 1 kW·m−2.

Constructed Wetland as a Low-Energy Technique for Wastewater Treatment – Seasonal Impact, Performance and Phytomanagement

Constructed Wetland as a Low-Energy Technique for Wastewater Treatment – Seasonal Impact, Performance and Phytomanagement

Cost-Effective Synthesis of MXene Cadmium Sulfide (CdS) for Heavy Metal Removal.

Background Environmental contamination resulting from the release of untreated industrial wastewater has emerged as a critical worldwide issue. These effluents frequently have high levels of heavy metals and antibiotics, which are bad for aquatic ecosystems and human health. Oftentimes, conventional wastewater treatment techniques fall short of effectively eliminating these pollutants. Innovative materials that may efficiently absorb or break down contaminants from contaminated water sources are, therefore, desperately needed. Hydrothermally produced MXene cadmium sulfide (CdS) composites have shown great promise as an adsorbent material because of their special qualities, which include high surface area, chemical stability, and customizable surface functions that improve their adsorption capacity for heavy metals and antibiotics alike. Aim The aim of this study is to produce MXene-CdS nanoparticles in a cost-effective method for the simultaneous removal of heavy metals from aqueous contaminants for water pollution control. Methods and materials MXenes were synthesized by selectively etching Ti3AlC2 MAX-phase ceramics using aqueous HF. CdS nanoparticles were synthesized separately and integrated with MXenes via a hydrothermal process. The resulting MXene CdS nanocomposites were characterized using scanning electron microscopy (SEM) for morphology, energy dispersion spectrum (EDS) for elemental composition, X-ray diffraction(XRD) study for phase identification, and removal of heavy metals viaMXene CdS. Results Consistent distribution of CdS nanoparticles on the MXene surface and the creation of MXene CdS nanomembranes with a well-defined shape were observed by SEM analysis. Ti, C, Cd, and S elements, indiciaries of a successful composite formation, were confirmed to be present by EDS. The crystalline structure of both the MXene and CdS phases was confirmed by the distinctive peaks seen in the XRD patterns. MXene-CdS composites facilitate the effective removal of chromium ions from contaminated water. The excellent hydrophilicity of the produced nanomembrane allowed for effective interaction with watery contaminants. Conclusion This study showcases the successful synthesis and characterization of MXene-CdS nanocomposites for environmental remediation, particularly in removing toxic metals like chromium from industrial effluents. SEM analysis confirmed the uniform distribution of CdS nanoparticles on the MXene surface, while elemental composition validated their integration. XRD analysis confirmed the crystalline structures of both components. The nanocomposite exhibited excellent hydrophilicity, enhancing the efficient adsorption of heavy metals. Its large surface area and chemical stability contribute to high adsorption efficiency, making it ideal for wastewater treatment. The scalable synthesis process supports practical applications. This research highlights MXene-CdS nanocomposites as a cost-effective, sustainable solution for water pollution control.

Comparing energy and exergy of multiple effect freeze desalination to MEE MSF RO

Freeze desalination is a promising technique for wastewater treatment and zero/minimum liquid discharge systems, often requiring multiple stages to produce potable water. This research focuses on developing a Multiple Effect Freeze Desalination (MEFD) system based on experimental data for Single-Stage Desalination Efficiency (SSDE) and Single-Stage Recovery Rate (SSRR). The study analyzes various MEFD setups, calculating cooling energy consumption and correlating it with electrical usage through the coefficient of performance (COP). Comparisons with Reverse Osmosis (RO), Multi Effect Evaporation (MEE), and Multi-Stage Flashing (MSF) suggest that MEFDs may face challenges in matching RO efficiency but can compete with MEE and MSF within specific operational ranges. Exergy assessments indicate difficulties against even 10-stage MSF systems. Achieving SSDE and SSRR levels above 65% enables MEFDs to rival 10-stage MSF plants in terms of energy efficiency, surpassing MEE and MSF at over 85% efficiency. Despite these challenges, MEFDs offer benefits for treating high salt concentrations and resisting corrosion.

An efficient, green, and magnetic recycling wastewater treatment technique enabled by ZnO/NiFe2O4/BiOBr 3D nanofibers photo-fenton process

A novel magnetic recycling ZnO/NiFe2O4/BiOBr 3D nanofibers photo-Fenton system was successfully prepared by parallel electrospinning combining with solvothermal method. ZnO/NiFe2O4 composite nanofibers was prepared via parallel electrospinning, then ZnO/NiFe2O4/BiOBr 3D nanofibers was obtained by solvothermal growth of BiOBr on electrospun ZnO/NiFe2O4 composite nanofibers. The composition, morphologies, structures and photocatalytic properties of ZnO/NiFe2O4/BiOBr 3D nanofibers were systematically tested and analyzed, and some meaningful results were obtained. The prepared ZnO/NiFe2O4/BiOBr 3D nanofibers, combined with H2O2, form a photo-Fenton system that exhibits excellent photocatalytic performance. When 0.05 mL of H2O2 is added to the photo-Fenton system, the degradation rate of organic dye Rhodamine B (RhB) reaches 99.61 % under light exposure for 10 min. Capture experiments and Electron Spin Resonance (ESR) measurements have confirmed that holes (h+) and hydroxyl radicals (·OH) are the primary active species that play a dominant role in the photocatalytic degradation of Rhodamine B (RhB). Furthermore, the ZnO/NiFe2O4/BiOBr 3D nanofibers have demonstrated exceptional photocatalytic degradation efficiency towards RhB, maintaining a degradation rate of over 95 % even after undergoing three recycling experiments. Significantly, this photo-Fenton system also has good magnetic properties, which can be separated from the treatment system under the applied magnetic field, avoiding secondary pollution of the treatment system, improving reuse rate and saving costs. This study provides valuable insights for the purposeful utilization of the photocatalytic materils.

Reviewing the Phenomenon of Antimicrobial Resistance in Hospital and Municipal Wastewaters: The Crisis, the Challenges and Mitigation Methods

Antibiotic resistance is a major crisis that the modern world is confronting. This review highlights the abundance of different types of antibiotic resistance genes (ARGs) in two major reservoirs in the environment, namely hospital and municipal wastewater, which is an unforeseen threat to human lives across the globe. The review helps understand the current state of affairs and the whereabouts on the dissemination of ARGs in both these environments. The various traditional wastewater treatment methods, such as chlorination and UV treatment, and modern methods, such as electrochemical oxidation, are discussed, and the gaps in these technologies are highlighted. The need for the development of newer techniques for wastewater treatment with enhanced efficiency is urgently underscored. Nanomaterial applications for ARG removal were observed to be less explored. This has been discussed, and prospective nanomaterials and nanocomposites for these applications are proposed.

Preparation of magnetite nanoparticles and their application in the removal of methylene blue dye from wastewater

Wastewater is discharged in large amounts from different industries; thus, wastewater treatment is currently one of the main concerns, advanced oxidation is a promising technique for wastewater treatment. This research aims to synthesize magnetite nanoparticles and study their application in wastewater treatment via adsorption and advanced oxidation processes. Magnetite nanoparticles were synthesized via coprecipitation technique between ferric and ferrous sulfate at a molar ratio of 2:1. The prepared sample was characterized using FTIR, XRD, TEM, BET surface area, zeta potential, VSM, and UV‒visible spectroscopy. XRD confirmed the formation of a single face-centered cubic (FCC) spinel structure of Fe3O4. TEM revealed an average particle size of 29.2 nm and a BET surface area of 70.1 m2 g−1. UV‒visible spectroscopy revealed that the UV–visible peak of the sample was obtained at 410 nm. VSM confirmed the attraction of the sample to a magnet with a magnetization of 60 (emu/g). The removal efficiency of methylene blue was studied using adsorption and advanced oxidation methods. For adsorption, the studied parameters were dye concentration 2–10 ppm, 3–10 pH, and 50:300 mg Fe3O4/L. For advanced oxidation, peroxide was used with nanomagnetite as a catalyst, and the studied parameters were pH 2–11, magnetite dose 20–200 PPM, and peroxide dose 500–2000 PPM. The removal efficiency by adsorption reached 95.11% by adding 50 mg of Fe3O4/L and 10 ppm dye conc at 6.5 pH; on the other hand, in advanced oxidation, it reached 98.5% by adding 110 PPM magnetite and 2000 ppm H2O2 at pH 11. The magnetite nanoparticles were reused for ten cycles of advanced oxidation, for a 10% reduction in removal efficiency at the tenth cycle.

A Review of the Dissemination of Antibiotic Resistance through Wastewater Treatment Plants: Current Situation in Sri Lanka and Future Perspectives.

The emergence of antibiotic resistance (AR) poses a significant threat to both public health and aquatic ecosystems. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for disseminating AR in the environment. However, only a limited number of studies have been conducted on AR dissemination through WWTPs in Sri Lanka. To address this knowledge gap in AR dissemination through WWTP operations in Sri Lanka, we critically examined the global situation of WWTPs as hotspots for transmitting antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) by evaluating more than a hundred peer-reviewed international publications and available national publications. Our findings discuss the current state of operating WWTPs in the country and highlight the research needed in controlling AR dissemination. The results revealed that the impact of different wastewater types, such as clinical, veterinary, domestic, and industrial, on the dissemination of AR has not been extensively studied in Sri Lanka; furthermore, the effectiveness of various wastewater treatment techniques in removing ARGs requires further investigation to improve the technologies. Furthermore, existing studies have not explored deeply enough the potential public health and ecological risks posed by AR dissemination through WWTPs.

Tracking SARS-CoV-2 and its variants in wastewater in Tunisia.

Wastewater-based genomic surveillance can improve community prevalence estimates and identify emerging variants of pathogens. Wastewater influents and treated effluents from six wastewater treatment plants (WWTPs) in Tunisia were analyzed between December 2021 and July 2022. Wastewater samples were analyzed with reverse transcription solid digital PCR (RT-sdPCR) and whole-genome sequencing to determine the amount of SARS-CoV-2 RNA and assign SARS-CoV-2 lineages. The virus variants detected in wastewater samples were compared with COVID-19 prevalence data. The quantitative results in wastewater influents revealed that viral RNA concentrations at the treatment plants corroborate with locally reported clinical cases and show an increase before the increment of clinically diagnosed new COVID-19 cases between April and July 2022. Delta and Omicron variants were identified in the Tunisian wastewater. Interestingly, the presence of variant BA.5 was detected in samples prior to its inclusion as a variant of concern (VOC) by the Tunisian National Health Authorities. SARS-CoV-2 was detected in wastewater effluents, indicating that the wastewater treatment techniques used in the majority of Tunisian WWTPs are inefficient in removing the virus traces. This study reports the first identification of SARS-CoV-2 VOCs in Tunisian wastewater samples.

Co-bioaugmentation with microalgae and probiotic bacteria: Sustainable solutions for upcycling of aquaculture wastewater and agricultural residues into microbial-rice bran complexes

Aquaculture farming generates a significant amount of wastewater, which has prompted the development of creative bioprocesses to improve wastewater treatment and bioresource recovery. One promising method of achieving these aims is to directly recycle pollutants into microbe-rice bran complexes, which is an economical and efficient technique for wastewater treatment that uses synergetic interactions between algae and bacteria. This study explores novel bioaugmentation as a promising strategy for efficiently forming microbial-rice bran complexes in unsterilized aquaculture wastewater enriched with agricultural residues (molasses and rice bran). Results found that rice bran serves a dual role, acting as both an alternative nutrient source and a biomass support for microalgae and bacteria. Co-bioaugmentation, involving the addition of probiotic bacteria (Bacillus syntrophic consortia) and microalgae consortiums (Tetradesmus dimorphus and Chlorella sp.) to an existing microbial community, led to a remarkable 5-fold increase in microbial-rice bran complex yields compared to the non-bioaugmentation approach. This method provided the most compact biofloc structure (0.50 g/L) and a large particle diameter (404 μm). Co-bioaugmentation significantly boosts the synthesis of extracellular polymeric substances, comprising proteins at 6.5 g/L and polysaccharides at 0.28 g/L. Chlorophyta, comprising 80% of the total algal phylum, and Proteobacteria, comprising 51% of the total bacterial phylum, are emerging as dominant species. These microorganisms play a crucial role in waste and wastewater treatment, as well as in the formation of microbial-rice bran complexes that could serve as an alternative aquaculture feed. This approach prompted changes in both microbial community structure and nutrient cycling processes, as well as water quality. These findings provide valuable insights into the transformative effects of bioaugmentation on the development of microbial-rice bran complexes, offering potential applications in bioprocesses for waste and wastewater management.

Ultrasonic destruction of surfactants

This study investigates the effectiveness of ultrasonic (US) treatment in removing and mineralizing surfactants in wastewater. It examines the complex mechanisms and variables (acoustic conditions, solution temperature, initial dose, etc.) that affect sonolytic processes. The effect of water matrix components (such as salts and the presence of secondary pollutants) on process performance is thoroughly investigated. Various treatments are analyzed through a detailed comparison of synergistic hybridization processes. The study also provides a comprehensive review of current environmental applications and explores potential directions for surfactant degradation using ultrasound. Insightful information is presented to advance sustainable wastewater treatment techniques. The literature review clearly reveals the promising future of sonotreatment for degrading various surfactants under different conditions. The use of multifrequency mechanisms and the integration of other advanced oxidation processes (AOPs) with the US process have significantly enhanced the energy efficiency of the sonochemical system. Additionally, the results highlight the need to focus on developing new sonoreactor designs, identifying degradation intermediates, and hybridizing the sonochemical system under innovative operating conditions.