Conventional Biological Treatment Research Articles

Insights into feasibility and microbial characterizations on simultaneous elimination of dissolved methane from anaerobic effluents and nitrate/nitrite reduction in a conventional anoxic reactor with magnetite

Discovery of nitrate/nitrite-dependent anaerobic methane oxidation (DAMO) challenges the conventional biological treatment processes, since it provides a possibility of simultaneously mitigating dissolved methane emissions from anaerobic effluents and reducing additional carbon sources for denitrification. Due to the slow growth of specialized DAMO microbes, this possibility has been just practiced with biofilms in membrane biofilm reactors or granular sludge in membrane bioreactors. In this study, simultaneous elimination of dissolved methane from anaerobic effluents and nitrate/nitrite reduction was achieved in a conventional anoxic reactor with magnetite. Calculations of electron flow balance showed that, with magnetite the eliminated dissolved methane was almost entirely used for nitrate/nitrite reduction, while without magnetite approximately 52 % of eliminated dissolved methane was converted to unknown organics. Metagenomic sequencing showed that, when dissolved methane served as an electron donor, the abundance of genes for reverse methanogenesis and denitrification dramatically increased, indicating that anaerobic oxidation of methane (AOM) coupled to nitrate/nitrite reduction occurred. Magnetite increased the abundance of genes encoding the key enzymes involved in whole reverse methanogenesis and Nir and Nor involved in denitrification, compared to that without magnetite. Analysis of microbial communities showed that, AOM coupled to nitrate/nitrite reduction was proceeded by syntrophic consortia comprised of methane oxidizers, Methanolinea and Methanobacterium, and nitrate/nitrite reducers, Armatimonadetes_gp5 and Thauera. With magnetite syntrophic consortia exchanged electrons more effectively than that without magnetite, further supporting the microbial growth.

Low-voltage stimulated denitrification performance of high-salinity wastewater using halotolerant microorganisms

Nitrate is a common contaminant in high-salinity wastewater, which has adverse effects on both the environment and human health. However, conventional biological treatment exhibits poor denitrification performance due to the high-salinity shock. In this study, an innovative approach using an electrostimulating microbial reactor (EMR) was explored to address this challenge. With a low-voltage input of 1.2 V, the EMR reached nitrate removal kinetic parameter (kNO3-N) of 0.0166–0.0808 h−1 under high-salinities (1.5 %-6.5 %), which was higher than that of the microbial reactor (MR) (0.0125–0.0478 h−1). The mechanisms analysis revealed that low-voltage significantly enhanced microbial salt-in strategy and promoted the secretion of extracellular polymeric substances. Halotolerant denitrification microorganisms (Pseudomonas and Nitratireductor) were also enriched in EMR. Moreover, the EMR achieved a NO3-N removal efficiency of 73.64 % in treating high-salinity wastewater (salinity 4.69 %) over 18-cycles, whereas the MR only reached 54.67 %. In summary, this study offers an innovative solution for denitrification of high-salinity wastewater

Mechanistic insight into the degradation of sulfadiazine by electro-Fenton system: Role of different reactive species

Sulfadiazine (SDZ), a widely used effective antibiotic, is resistant to conventional biological treatment, which is concerning since untreated SDZ discharge can pose a significant environmental risk. Electro-Fenton (EF) technology is a promising advanced oxidation technology for efficiently removing SDZ. However, due to the limitations of traditional experimental methods, there is a lack of in-depth study on the mechanism of ·OH-dominated SDZ degradation in EF process. In this study, an EF system was established for SDZ degradation and the transformation products (TPs) were detected by mass spectrometry. Dynamic thermodynamic, kinetic and wave function analysis of reactants, transition states and intermediates were proposed by density functional theory calculations, which was applied to elucidate the underlying mechanism of SDZ degradation. Experimental results showed that amino, benzene, and pyrimidine sites in SDZ were oxidized by ·OH, producing TPs through hydrogen abstraction and addition reactions. ·OH was kinetically more likely to attack SDZ- than SDZ. Fe(IV) dominated the single-electron transfer oxidation reaction of SDZ, and the formed organic radicals can spontaneously generate the de-SO2 product via Smiles rearrangement. Toxicity experiments showed the toxicity of SDZ and TPs can be greatly reduced. The results of this study promote the understanding of SDZ degradation mechanism in-depth. Environmental ImplicationSulfadiazine (SDZ) is one of the antibiotics widely used around the world. However, it has posed a significant environmental risk due to its overuse and cannot be efficiently removed by traditional treatment methods. The lack of in-depth study on SDZ degradation mechanism under reactive species limits the improvement of SDZ degradation efficiency. Therefore, this work focused on SDZ degradation mechanism in-depth under electro-Fenton system through reactive species investigation, mass spectrometry analysis, and theoretical calculation. The results in this study can provide a theoretical basis for improving the SDZ degradation efficiency which will contribute to solving SDZ pollution problems.

Magnetic γ-Fe2O3/ZnO@CNTs synthesized by a green precipitation method for the degradation of aniline through photocatalysis coupling catalytic ozonation

Aniline is highly toxic and difficult to degrade by conventional biological treatment processes. Thus, more efficient processing technology needs to be developed. Photocatalysis coupling catalytic ozonation (PCO) could be a solution. In this study, a green precipitation method was used to synthesize a γ-Fe2O3/ZnO@CNT catalyst, which exhibits high activity for aniline PCO degradation and strong magnetic properties for rapid separation. Under the optimal conditions, the aniline removal rate reached 93.5%. After 5 reaction cycles, the γ-Fe2O3/ZnO@CNT catalysts can be separated easily with a magnet, and a 91% aniline removal rate can be maintained. Furthermore, there are at least 4 kinds of advanced oxidation processes (AOPs) in this system, i.e., (1) photocatalytic oxidation; (2) catalytic ozonation; (3) photocatalytic ozone; and (4) Fenton oxidation. Thus, a novel stable and magnetically separable catalyst was developed, and new insight were provided for the role of PCO processes in the treatment of aniline.

Assessing the Efficiency and Role of Duckweed (Lemna Minor) in the Removal of Pollutants from Wastewater Treatment Plant Secondary Clarifier Tanks: A Comprehensive Review

Aquatic plants, including duckweed (Lemna minor), are increasingly utilized in sewage and wastewater treat-ment to improve pollution parameters and organic matter removal. This study aimed to investigate the impacts and efficacy of duckweed in secondary clarifier tanks in a conventional biological treatment facility. The per-formance of four secondary clarifiers with and without duckweed was compared based on water quality efflu-ent and settling characteristics. As per the experiment results, the secondary clarifier tank with duckweed demonstrated higher removal efficiency for chemical oxygen demand (COD), biological oxygen demand (BOD5), ammonium, phosphate, total nitrogen (TN), and total phosphorus (TP) – of 70%, 75%, 72%, 82%, 67%, and 96%, respectively, compared to the tank without duckweed. The concentration of suspended solids in the effluent and sludge volume index (SVI) values were similar in both settings. The research findings suggest that duckweed can contribute to the treatment efficiency of conventional biological treatment plants, thus re-ducing the need for tertiary nutrient removal. Additionally, the cost-effectiveness of treatment with duckweed and its reuse as fertilizer and animal fodder make it a valuable resource. The optimal temperature for duck-weed growth is approx. +26°C, and it is influenced by sunlight and temperature more than nutrient concentra-tions.

Holistic managements of textile wastewater through circular, greener and eco-innovative treatment systems developed by minimal to zero liquid discharge

New pragmatic and viable solutions to reduce or prevent discharge and to protect reserves are currently among the top-prioritised research for cleaner, circular, and resource-efficient use of industrial waters. So, the development of eco-sustainable water management is essential for green industrial development that will meet versatile and eco-sensitive regulatory standards, especially in water-intensive industries. Textile wastewater was reclaimed in semi to fully closed loops for minimal to zero liquid discharge. Concentrate-mixed wastewater was steadily treated in a hybrid membrane oxidation reactor at 60–80 % synergistic performances with remarkable UF fluxes of 96.4–820 L/m2h without any sludge discharge. Effluent was purified with 90–100 % removals and 20–80 L/m2h in nanofiltration and reverse osmosis. Due to Fenton-specific operation, more handling by ion exchange and neutralisation required to harvest membrane reuse waters and reactor discharge effluents with guaranteed Fe and pH. All-in-one system simulations indicated that high quality reuse waters are produced by 99.9 % efficiency and 98 and 100 % savings in iron and acid but 20–51 % more oxidant through concentrate recycling and regenerant reuse. It was also revealed that reactor effluents can be released to the sea or conventional biological treatment or can be eco-sustainably exploited for in-situ chemical and ex-situ bio-induced recovery of vivianite. This research demonstrates that how textile wastewater can be managed holistically by liquid discharge approaches from 50 % minimal to 99.9 % zero just in two-step, i.e. pretreatment and pre-concentration, with consumable minimisation and valuable waste recovery through the eco-innovative systems which are developed as circular, greener, and sludge-free compatible with sustainable development goals.

Feasibility of phenolic contaminant removal from high-saline wastewater by chloride-mediated activation of peroxymonosulfate (PMS) and peracetic acid (PAA)

Phenolic pollutants are highly toxic and can affect the growth and reproduction of aquatic organisms, as well as contaminate drinking water resources, posing a significant threat to both ecological and human health. However, conventional biological treatment processes are constrained in treating high salinity organic wastewaters due to the potentially lethal effects of high concentrations of dissolved salts on microorganisms. While advanced oxidation processes have shown promise in removing phenolic contaminants from high-saline wastewater, their widespread application is always limited by the high costs associated with energy and chemical usage. In this study, we explored the potential application of directly introducing peroxymonosulfate (PMS) and peracetic acid (PAA) to high-salinity water for the removal of nine phenolic contaminants. By establishing a correlation between the degradation rate constants in the PMS/Cl– (kPMS) and PAA/Cl– (kPAA) systems and various molecule descriptors, two multiple linear regression models were developed to predict the degradation rate constants under investigation. Additionally, we selected bisphenol A (BPA) as the target contaminant and investigated the impact of common ions found in natural water, such as HCO3–, NO3–, and humic acid, on the removal of BPA using two systems. Finally, we conducted experiments using tap water and sewage water to demonstrate the practical application and performance of the two systems. These experiments aimed to provide valuable insights into the influence of background chloride on PMS and PAA activation, as well as the potential of direct PMS/PAA introduction for eliminating phenolic micropollutants from high-saline wastewaters.

Exploring biorefinery alternatives for biowaste valorization: a techno-economic assessment of enzymatic hydrolysis coupled with anaerobic digestion or solid-state fermentation for high-value bioproducts

ABSTRACT Enzymatic hydrolysis of organic waste is gaining relevance as a complementary technology to conventional biological treatments. Moreover, biorefineries are emerging as a sustainable scenario to integrate waste valorization and high-value bioproducts production. However, their application on municipal solid waste is still limited. This study systematically evaluates the techno-economic feasibility of the conversion of the organic fraction of municipal solid waste (OFMSW) into high-value bioproducts through enzymatic hydrolysis. Two key variables are examined: (a) the source of the enzymes: commercial or on-site produced using OFMSW, and (b) the treatment of the solid hydrolyzate fraction: solid-state fermentation (SSF) for the production of biopesticides or anaerobic digestion for the production of energy. As a result, four different biorefinery scenarios are generated and compared in terms of profitability. Results showed that the most profitable scenario was to produce enzymes on-site and valorize the solid fraction via SSF, with an internal rate of return of 13%. This scenario led to higher profit margins (74%) and a reduced payback time (6 years), in contrast with commercial enzymes that led to an unprofitable biorefinery. Also, the simultaneous production of higher-value bioproducts and energy reduced the economic dependence of OFMSW treatment on policy instruments while remaining energetically self-sufficient. The profitability of the biorefinery scenarios evaluated was heavily dependent on the enzyme price and the efficiency of the anaerobic digestion process, highlighting the importance of cost-efficient enzyme production alternatives and high-quality OFMSW. This paper contributes to understanding the potential role of enzymes in future OFMSW biorefineries and offers economical insights on different configurations.

Cytoprotective alginate microcapsule serves as a shield for microalgal encapsulation defensing sulfamethoxazole threats and safeguarding nutrient recovery

Microalgal encapsulation technology is expected to broaden more possibilities for employing microalgae for upgrading conventional biological wastewater treatment. However, only limited and fragmented information is currently available on microalgal encapsulation and pollutant removal. It is ambiguous whether it hold potential for wastewater treatment. Particularly, it remains to be determined whether this technology can provide more possibilities in harsh sewage environments. Here, potential of encapsulated technology to recover nutrients from wastewater was examined, simultaneously compared with commonly adopted suspended system. Results indicate the encapsulated microalgal system showed outstanding advantages in nutrient recovery and defense against antibiotic threats. Moreover, by examining the cellular oxidative stress response and changes of the photosynthetic system, the encapsulated system exhibited potential cytoprotective advantages to microalgal cells for defensing antibiotic threats. Molecular dynamics simulation revealed that the differences among superficial aggregation between the nutrients’ ions and molecular sulfamethoxazole on the cross-linked alginate microcapsule surface dominated the nutrient recovery and cytoprotective functions. Ultimately, the molecular nature of pollutants was found to be the most critical aspect for predicting application of this microalgal microcapsule. Cytoprotective systems created with alginate microcapsules can potentially handle more diverse threats with a single type of surface charge in their outermost layer.

PFAS-Free Carbon Electrodes for Efficient Micropollutants Removal through Heterogeneous Electro-Fenton: From Material Synthesis to Module Design

Emerging micropollutants (MPs) in water bodies such as pharmaceuticals, pesticides, personal care products, and per-and poly-fluoroalkyl substances (PFAS) have posed environmental, ecological, and anthropological issues since MPs are too persistent to be degraded by conventional biological treatment. On the other hand, electrochemical advanced oxidation processes (EAOPs) have proved themselves as efficient and robust techniques to unselectively degrade MPs by forming OH radicals (•OH). Among EAOPs, electro-Fenton, or more specifically heterogeneous electro-Fenton (HEF), suggests an eco-friendly and energy-efficient treatment technique with a wide pH range for removing persistent MPs. In HEF, hydrogen peroxide (H2O2) is electrochemically produced on the cathode surface, which can react with immobilized, adjacent Fe catalysts for •OH generation. Yet, one challenge for HEF is that most of the studies have primarily focused on synthesizing Fe-containing carbons as a catalyst that suffers from several delicate preparation steps, which are time-, chemical-, and energy-consuming and lack reusability over consecutive runs [1].Additionally, these catalysts are usually powders, entailing adding polymeric binders for the immobilization of the catalyst layer on electrodes. The presence of polymeric binders, e.g., polytetrafluoroethylene (PTFE)—as PFAS-containing compounds on the electrode surface—enhances the risk of PFAS contamination during the HEF process due to mechanical wear-off or degradation under the harsh oxidative condition caused by the formation of unselective •OH. Therefore, developing PFAS-free carbon electrodes for the HEF process offering facile fabrication and good reusability with a scaling-up perspective is imperative to enable decentralized solutions for MPs removal, especially highly recalcitrant PFAS. In this work, freestanding carbons made of bio-based precursors, chitosan and sucrose, serve as electrodes for the HEF process. Chitosan is the backbone for the self-standing feature and a nitrogen-rich biopolymer, while sucrose serves as a carbon-rich compound. The mixture of chitosan and sucrose undergoes silica- and ice-templating to make a hierarchically porous carbon [2]. Bio-based carbons illustrated their capability for oxygen reduction reactions, particularly the electro-generation H2O2 [3]. As-synthesized carbons proved to remove carbamazepine and sulfamethoxazole as two persistent MPs at pH 3 and pH 7 [3]. Moreover, a novel flow-through electrolysis module equipped with as-synthesized carbons has been designed and operated to remove 20 mg/L CBZ solution at a current density of 20 mA/cm2. This module design demonstrates the ease of scaleup for a decentralized water/wastewater treatment unit to remove highly recalcitrant MPs.

Enhanced removal of phenol and chemical oxygen demand from coking wastewater using micro and nano bubbles: Microbial community and metabolic pathways

The treatment of coking wastewater with high phenol concentrations has been a challenge for conventional biological treatment technology. In this short communication, phenol-degrading bacteria domesticated by micro and nano bubbles (MNBs) water are used to treat the high- concentration phenol in an MNBs aeration reactor (MNB-AR). The results show that the MNB-AR can greatly improve the removal of phenol and chemical oxygen demand (COD). At a phenol concentration of 1000 mg L−1, the phenol and COD removal rates in the MNB-AR are 55 % and 39 % higher than in the conventional bubble aeration reactor respectively. MNB-AR performs more stably and reaches a higher phenol tolerance under fluctuating high-phenol-concentration loadings. Metagenomic analysis shows that MNBs promote the growth and metabolism of aerobic microorganisms related to phenol degradation, and enhance gene abundance related to carbon metabolism. MNBs aeration combined with microorganisms is an efficient solution for treating coking wastewater.

Crystal violet degradation in the ozone/persulfate/ferroferric oxide system: A heterogeneous catalytic process for simultaneous catalysis of ozone and persulfate

Crystal violet (CV) is a widely used cationic triphenylmethane dye, mostly from textile, leather and other industrial manufacturing companies. The carcinogenicity, teratogenicity and mutagenicity of crystalline violet have received widespread attention, but due to the toxicity of crystalline violet itself, the It is difficult to degrade crystal violet by conventional wastewater biological treatment system. In this study, Fe3O4 was used to activate ozone and persulfate to degrade crystal violet in water. The results showed that the degradation of crystal violet followed a pseudo-second-order kinetic model and logistic model in the O3/PDS/Fe3O4 system, there was an obvious synergistic effect among ozone, persulfate, and Fe3O4. The effect of chelating agents and background components in aqueous solution on the degradation of crystalline violet in the O3/PDS/Fe3O4 system was investigated. The Radical quenching experiments and electron spin resonance spectra show that the generation of SO4•-, •OH, and 1O2 is the main cause of crystal violet degradation. After eight reuses of ferroferric oxide, the catalytic activity of Fe3O4 slightly decreased, but it still showed a high removal effect on crystal violet. The catalysis of Fe3O4 in O3/PDS/Fe3O4 system is mainly carried out by heterogeneous catalytic process, including electron transfer in Fe(Ⅱ)/Fe(Ⅲ) redox and lattice oxygen, catalytic ozonation process of surface hydroxyl groups. The O3/PDS/Fe3O4 system has an EE/O of 139.23 kWh·m−3 per order, indicating a higher energy efficiency compared to the other process. Intermediate products of CV degradation were identified by ultraviolet absorption spectrometry and liquid chromatography-mass spectrometry (LC-MS), and the degradation pathways of CV were determined.

Long-term stable and efficient degradation of ornidazole with minimized by-product formation by a biological sulfidogenic process based on elemental sulfur

Conventional biological treatment processes cannot efficiently and completely degrade nitroimidazole antibiotics, due to the formation of highly antibacterial and carcinogenic nitroreduction by-products. This study investigated the removal of a typical nitroimidazole antibiotic (ornidazole) during wastewater treatment by a biological sulfidogenic process based on elemental sulfur (S0-BSP). Efficient and stable ornidazole degradation and organic carbon mineralization were simultaneously achieved by the S0-BSP in a 798-day bench-scale trial. Over 99.8 % of ornidazole (200‒500 μg/L) was removed with the removal rates of up to 0.59 g/(m3·d). Meanwhile, the efficiencies of organic carbon mineralization and sulfide production were hardly impacted by the dosed ornidazole, and their rates were maintained at 0.15 kg C/(m3·d) and 0.49 kg S/(m3·d), respectively. The genera associated with ornidazole degradation were identified (e.g., Sedimentibacter, Trichococcus, and Longilinea), and their abundances increased significantly. Microbial degradation of ornidazole proceeded by several functional genes, such as dehalogenases, cysteine synthase, and dioxygenases, mainly through dechlorination, denitration, N-heterocyclic ring cleavage, and oxidation. More importantly, the nucleophilic substitution of nitro group mediated by in-situ formed reducing sulfur species (e.g., sulfide, polysulfides, and cysteine hydropolysulfides), instead of nitroreduction, enhanced the complete ornidazole degradation and minimized the formation of carcinogenic and antibacterial nitroreduction by-products. The findings suggest that S0-BSP can be a promising approach to treat wastewater containing multiple contaminants, such as emerging organic pollutants, organic carbon, nitrate, and heavy metals.

An Overview of Wastewater Treatment and Reuse in The Gulf Cooperation Council Countries

The human population generates a substantial amount of waste, and if it is discarded without any treatment it can lead to environmental degradation. This is commonly executed by discharging substantial amount of untreated wastewater in the waterways. Wastewater can be generated from numerous locations but for this review the principal areas concerned are municipalities and industries. The focus of the current study relies on performing a thorough review on expressing the benefits of treating wastewater, assessing Gulf Cooperation Council (GCC) reuse regulations associated with wastewater reuse, identifying different wastewater treatment technologies, and evaluating previous research implemented on this field across the GCC region. Various case studies about treatment technologies and reuse regulations are analyzed in this review for each country within the GCC. The findings show that treating wastewater holds many benefits such as reducing environmental pollution and can aid in helping nations with limited access to fresh water to meet their demand. The technologies for treating wastewater are discussed, such as: conventional filtration, chemical, biological treatment, and different membrane technologies. The review conveys that although treating water has many benefits, there are still many challenges associated with the cost, public perception, and management policies that need to be resolved. To improve wastewater treatment policies effective management can show greater potential for mitigating the freshwater shortage in the GCC countries. Also, since each GCC country has different policies regarding wastewater management, more research should be conducted in the future to adapt as the GCC territory is competing to produce new wastewater treatment plants to accommodate their growing demand for fresh water.

The utilization of microwaves in revitalizing peroxymonosulfate for tetracycline decomposition: optimization via response surface methodology

Abstract Antibiotic contamination in water has received significant attention in recent years for the reason that the residuals of antibiotics can promote the progression of antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs). It is difficult to treat antibiotics using conventional biological treatment methods. In order to investigate an efficient new method of treating antibiotics in water, in this study, microwave (MW) was employed in revitalizing peroxymonosulfate (PMS) to treat typical antibiotic tetracycline (TC). The Box–Behnken design (BBD) was applied to organize the experimental schemes. The response surface methodology (RSM) optimization was run to derive the best experimental conditions and validated using actual data. Moreover, the main mechanisms of PMS activation via MW were resolved. The results demonstrated that the relationship between TC removal rate and influencing factors was consistent with a quadratic model, where the P-value was less than 0.05, and the model was considered significant. The optimal condition resulting from the model optimization were power = 800 W, [PMS] = 0.4 mM, and pH = 6.0. Under such conditions, the actual removal of TC was 99.3%, very close to the predicted value of 99%. The quenching experiment confirmed that SO4•− and •OH were jointly responsible for TC removal.

The Influence of Atmospheric Pressure and Organic Loading on the Sustainability of Simultaneous Nitrification and Denitrification

In high-altitude regions, a diminished atmospheric oxygen content significantly impairs the aeration efficiency of municipal wastewater, posing a challenge to sustainable wastewater management. Consequently, conventional biological wastewater treatment methods necessitate elevated energy consumption in high-altitude areas, rendering them economically and environmentally unsustainable. The simultaneous nitrification and denitrification (SND) process, owing to its minimal oxygen requirements, emerges as a promising and sustainable solution in low-pressure environments. Additionally, owing to the unique lifestyle and natural conditions in plateau regions, the organic loading in municipal wastewater is often low. To comprehensively assess the impact of low pressure and organic loading on the SND process, three laboratory-scale reactors were implemented. This study revealed that low pressure and the introduction of organic matter enhanced both nitrogen removal performance and SND efficiency. The sludge volume index decreased by 93.5%, indicating a substantial improvement in the microbial aggregation ability and the formation of a more favorable SND sludge structure. 16S rRNA sequencing results demonstrated alterations in the microbial community structure due to low pressure and the addition of organic matter, leading to a substantial increase in the abundance of nitrifying and denitrifying bacteria. Furthermore, the prediction results of functional genes indicated the upregulation of genes related to the nitrification and denitrification processes with decreasing pressure and the addition of organic matter. This enhancement underlines the improved microbial nitrogen removal function. This study underscores the positive influence of low pressure and organic loading on the SND system, thereby substantially enhancing the economic and environmental sustainability of the SND process in plateau regions.

Reduced TiO2 nanotube arrays as environmental catalysts that enable advanced oxidation processes: A mini review

Advanced oxidation processes (AOPs) that utilize heterogeneous catalysts are an engaging and compelling technology for treating emerging contaminants in water and wastewater. Substantial efforts have been devoted to developing cost-effective and environmentally benign materials for application in AOPs. Reduced TiO2 nanotube arrays (r-TNAs) have recently emerged as promising environmental materials for efficiently mitigating persistent organic pollutants (POPs) resistant to conventional biological treatment. r-TNAs possess distinct electrical, optical, and catalytic features, including superior conductivity and solar light absorption due to structural defects involving oxygen vacancies and Ti3+ states. Moreover, their well-organized open channel structures provide a substantial surface area, facilitating the efficient mass transfer of reactants and products. Notably, r-TNAs can be grown directly on the substrate without using organic adhesives or binders, which improves their mechanical and chemical durability and facilitates their repeated use. This article represents the pioneering comprehensive review of r-TNAs in AOP applications. We introduce an electrochemical anodization technique to fabricate TNAs and summarizes the reduction methods employed in r-TNA synthesis. We also elucidate the appealing attributes of r-TNAs and explore their applications in emerging AOPs, including persulfate activation, electrocatalysis, and photo(electro)catalysis. Finally, we outline critical challenges and provide insights into future prospects for the development of AOP systems based on r-TNAs.

Novel strategy for treating high salinity oilfield produced water: Pyrite-activated peroxymonosulfate coupled with heterotrophic ammonia assimilation

Existing conventional biological treatment techniques face numerous limitations in effectively removing total petroleum hydrocarbons (TPHs) and ammonia (NH4+-N) from oilfield-produced water (OPW), highlighting the pressing need for innovative pre-oxidation and biological treatment processes. In this study, a pyrite-activated peroxymonosulfate (PMS)-coupled heterotrophic ammonia assimilation (HAA) system was established to achieve satisfactory system performance for OPW treatment. Pyrite sustained-release Fe2+-activated PMS was used to produce SO4•− and •OH, and 71.0 % of TPHs were effectively removed from the oil wastewater. The average TPHs and NH4+-N removal efficiencies in the test group with pre-oxidation were 96.9 and 98.3 %, compared to 46.5 and 77.1 % in the control group, respectively. The maximum fluorescence intensities of tryptophan protein and aromatic protein in the test group declined by 83.7 %. Fourier transform ion cyclotron resonance mass spectrometry revealed that pre-oxidation degraded more long-chain hydrocarbons and aromatic family compound, whereas the HAA process produced more proteins and carbohydrates. Pyrite-PMS promoted the enrichment of ammonia-assimilating bacteria, alleviating the explosive increase in extracellular polymeric substances and reducing sludge settleability. The low cost, efficiency, green chemistry principles, and synergies of this approach make it a powerful solution for practical OPW treatment to reduce environmental impacts and promote sustainable wastewater treatment.

How to choose the best tertiary treatment for pulp and paper wastewater? Life cycle assessment and economic analysis as guidance tools

Pulp and paper wastewater (P&P WW) often requires tertiary treatment to remove refractory compounds not eliminated by conventional biological treatment, ensuring compliance with high-quality effluent discharge or reuse standards. This study employs a life cycle assessment (LCA) methodology to compare alternative tertiary treatment technologies for P&P WW and rank them accordingly. The evaluated technologies in the scenarios include inorganic (S1) and organic (S2) coagulation-flocculation, ozonation (O3) (S3), O3+granular activated carbon (GAC) (S4), and ultrafiltration (UF)+reverse osmosis (RO) (S5). The analysis focuses on a P&P wastewater treatment plant (WWTP) in Northeastern Italy. The LCA is complemented by an economic analysis considering each technology's capital and operating costs, as well as potential revenues from internal effluent reuse. Results indicate that S4 (O3+GAC) outranks all the other scenarios in terms of both environmental performance and economic viability, primarily due to the advantages associated with effluent reuse. S5 (UF+RO), which also involves reuse, is limited by the high energy consumption of UF+RO, resulting in increased environmental impacts and costs. The physicochemical scenario S2 (Chem Or), currently utilized in the WWTP under study, remains the best-performing technology in the absence of effluent reuse. In contrast, S3 (O3 alone) exhibits the poorest environmental and economic outcomes due to substantial energy requirements for O3 generation and the inability to reuse the treated effluent directly. Lastly, a sensitivity analysis underscores the strong influence of chemical dosages in S1 and S2 on environmental and economic impacts, which is more significant than the impact of water reuse percentages in S4 and S5. The high electricity cost observed during 2022 negatively affects the energy-intensive scenarios (S3-S5), making coagulation-flocculation (S1-S2) even more convenient.

Antibiotic resistances from slaughterhouse effluents and enhanced antimicrobial blue light technology for wastewater decontamionation

The frequencies of 6 different facultative pathogenic bacteria of the ESKAPE group (priority list WHO) and a total of 14 antibiotic resistance genes (ARGs) with different priorities for human medicine were quantified in wastewaters of poultry and pig slaughterhouses using molecular biological approaches. Raw sewage from poultry and pig slaughterhouses was found to be contaminated not only with facultative pathogenic bacteria but also with various categories of clinically relevant ARGs, including ARGs against the reserve antibiotics group. The concentration of the different gene targets decreased after on-site conventional biological or advanced oxidative wastewater treatments, but was not eliminated. Hence, the antimicrobial BlueLight (aBL) in combination with a porphyrin photo-sensitizer was studied with ESKAPE bacteria and real slaughterhouse wastewaters. The applied broad LED-based blue light (420–480 nm) resulted in groups of sensitive, intermediate, and non-sensitive ESKAPE bacteria. The killing effect of aBL was increased in the non-sensitive bacteria Klebsiella pneumoniae and Enterococcus faecium due to the addition of porphyrins in concentrations of 10−6 M. Diluted slaughterhouse raw wastewater was treated with broad spectrum aBL and in combination with porphyrin. Here, the presence of the photo-sensitizer enhanced the aBL biocidal impact.