Biological Treatment Technologies Research Articles

Emerging trends in POME treatment and applications: chemical and biotechnological aspects

Globally, environmental challenges are growing more and more significant. Changes in soil have been caused by the years-long discharge and careless disposal of palm oil mill effluent (POME). A systematic review explored emerging trends in POME treatment and applications, with a focus on recent, innovative methods for POME treatment with biological and chemical treatment technologies, chemical and biotechnological approaches. The review highlighted several key findings, including the efficiency and cost-effectiveness of these approaches, their ability to reduce environmental impacts, and their potential to recover resources such as energy and nutrients. Quantitative information on the efficacy of these approaches was also provided. Based on these findings, the review concludes that the aforementioned approaches can significantly improve POME treatment and offer a promising way to reduce environmental impacts and recover resources. However, further research is needed to optimize and scale up these approaches, as well as to assess their long-term sustainability. In addition, it is important to consider the social, economic, and environmental factors that may affect the successful implementation of these approaches.

Salt stimulates sulfide−driven autotrophic denitrification: Microbial network and metagenomics analyses

Sulfur autotrophic denitrification (SADN) is a promising biological wastewater treatment technology for nitrogen removal, and its performance highly relies on the collective activities of the microbial community. However, the effect of salt (a prevailing characteristic of some nitrogen−containing industrial wastewaters) on the microbial community of SADN is still unclear. In this study, the response of the sulfide−SADN process to different salinities (i.e., 1.5 % salinity, 0.5 % salinity, and without salinity) as well as the involved microbial mechanisms were investigated by molecular ecological network and metagenomics analyses. Results showed that the satisfactory nitrogen removal efficiency (>97 %) was achieved in the sulfide−SADN process (S/N molar ratio of 0.88) with 1.5 % salinity. In salinity scenarios, the genus Thiobacillus significantly proliferated and was detected as the dominant sulfur−oxidizing bacteria in the sulfide−SADN system, occupying a relative abundance of 29.4 %. Network analysis further elucidated that 1.5 % salinity had enabled the microbial community to form a more densely clustered network, which intensified the interactions between microorganisms and effectively improved the nitrogen removal performance of the sulfide−SADN. Metagenomics sequencing revealed that the abundance of functional genes encoding for key enzymes involved in SADN, dissimilatory nitrate reduction to ammonium, and nitrification was up−regulated in the 1.5 % salinity scenario compared to that without salinity, stimulating the occurrence of multiple nitrogen transformation pathways. These multi−paths contributed to a robust SADN process (i.e., nitrogen removal efficiency >97 %, effluent nitrogen <2.5 mg N/L). This study deepens our understanding of the effect of salt on the SADN system at the community and functional level, and favors to advance the application of this sustainable bioprocess in saline wastewater treatment.

Application and effect evaluation of membrane bioreactor technology in municipal wastewater treatment

Due to the increasing amount of urban sewage and improved standards in sewage discharge, simple traditional biological sewage treatment fails to meet the needs of municipal sewage treatment. Therefore, to treat wastewater more efficiently, the process of combining biofilm technology with traditional biological wastewater treatment appeared. This paper analyzes the advantages and problems of the combined processes of membrane separation technology and traditional biological sewage treatment technology from and perspective of complementary processes, and puts forward relevant measures to alleviate membrane fouling. The study found that Membrane Bioreactor (MBR) technology occupies a small area, and has a better sewage effluent quality and strong stability, also the sludge output is low. Anaerobic Membrane Bioreactor (AnMBR) technology can increase the effectiveness of removing organic matter and enable resource reuse, which satisfies the demand for low energy consumption. Membrane Aeration Bioreactor (MABR) technology involves bubble-free aeration that greatly improves the quality of sewage effluent, and the production of sludge in MABR technology decreases. Anaerobic ammonium nitrogen membrane bioreactor technology can enhance the efficiency of Anammox bacteria, and the energy consumption and economic cost of this technology are low. Although these membrane combination processes can effectively treat sewage, they can easily be limited by factors such as temperature, microbial communities, and membrane fouling. This paper provides guiding opinions for decision makers in the field of urban sewage treatment so that they can apply appropriate sewage treatment technology to local municipal sewage treatment, promoting the sustainable development of sewage treatment.

The impact of ozone treatment on the removal effectiveness of various refractory compounds in wastewater from petroleum refineries

Large volumes of wastewater are generated during petroleum refining processes. Petroleum refinery wastewater (PRW) can contain highly toxic compounds that can harm the environment. These toxic compounds can be a challenge in biological treatment technologies due to the effects of these compounds on microorganisms. These challenges can be overcome by using ozone (O3) as a standalone or as a pretreatment to the biological treatment. Ozone was used in this study to degrade the organic pollutants in the heavily contaminated PRW from a refinery in Mpumalanga province of South Africa. The objective was achieved by treating the raw PRW using ozone at different ozone treatment times (15, 30, 45, and 60 min) at a fixed ozone concentration of 3.53 mg/dm3. The ozone treatment was carried out in a 2-liter custom-designed plexiglass cylindrical reactor. Ozone was generated from an Eco-Lab-24 corona discharge ozone generator using clean, dry air from the Afrox air cylinder as feed. The chemical oxygen demand, gas chromatograph characterization, and pH analysis were performed on the pretreated and post-treated PRW samples to ascertain the impact of the ozone treatment. The ozone treatment was effective in reducing the benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds in the PRW. The 60-min ozone treatment of different BTEX pollutants in the PRW resulted in the following percentage reduction: benzene 95%, toluene 77%, m + p-xylene 70%, ethylbenzene 69%, and o-xylene 65%. This study has shown the success of using ozone in reducing the toxic BTEX compounds in a heavily contaminated PRW.

Reservoir Desilting and Treatment of Silted Sediment

This paper aims to explore the significance and methods of sediment treatment in reservoirs. It first analyzes the impact of sediment on protective engineering, highlighting how sediment reduction exacerbates soil erosion and riverbed siltation, directly threatening the safety of protective engineering. Next, it introduces the application of compound fingerprint identification method in sediment source analysis, which accurately identifies sediment sources by comprehensively considering multiple characteristics, providing crucial scientific basis for protective engineering. The paper then discusses three main sediment treatment methods: mechanical dredging technology, sedimentation tank treatment, and biological treatment. Mechanical dredging technology is simple and efficient but suffers from issues like noise and high maintenance costs. Sedimentation tank treatment effectively improves water quality, while biological treatment technology has recently gained significant attention for purifying water bodies using microorganisms and plants, enhancing ecological quality. In conclusion, the paper emphasizes the importance of selecting suitable treatment methods based on specific conditions to achieve maximum efficiency and cost-effectiveness.

Response surface methodology for process optimization in livestock wastewater treatment: A review

With increasing demand for meat and dairy products, the volume of wastewater generated from the livestock industry has become a significant environmental concern. The treatment of livestock wastewater (LWW) is a challenging process that involves removing nutrients, organic matter, pathogens, and other pollutants from livestock manure and urine. In response to this challenge, researchers have developed and investigated different biological, physical, and chemical treatment technologies that perform better upon optimization. Optimization of LWW handling processes can help improve the efficacy and sustainability of treatment systems as well as minimize environmental impacts and associated costs. Response surface methodology (RSM) as an optimization approach can effectively optimize operational parameters that affect process performance. This review article summarizes the main steps of RSM, recent applications of RSM in LWW treatment, highlights the advantages and limitations of this technique, and provides recommendations for future research and practice, including its cost-effectiveness, accuracy, and ability to improve treatment efficiency.

Global occurrence of organic micropollutants in surface and ground water: Highlighting the importance of wastewater sanitation to tackle organic micropollutants

The occurrence, fate and distribution of organic micropollutants (OMPs) in different water matrices is of increasing concern due to the negative effects towards flora, fauna and human health. This metadata study provides an updated picture of the global occurrence of OMPs in freshwater and wastewater in five geographical regions, and illustrates how socioeconomic factors are key elements that influence the concentration of these OMPs in the different water matrices. The study also aims to provide a collated database of OMPs removal efficiencies achieved by the different biological treatment technologies. Our findings demonstrated that OMPs like acetaminophen, ibuprofen, and triclosan are present globally in freshwater (> 500 ng/L) and wastewater (> 10, 000 ng/L), and at relatively higher concentrations than the other evaluated OMPs. Significant correlations between OMPs concentration in wastewater versus freshwater demonstrated wastewater to be a potential source of certain OMPs to the freshwater environment. This was further confirmed through correlation between OMPs concentration and socioeconomic factors like infrastructure index and governance index in both wastewater and freshwater. These results highlighted the importance of wastewater sanitation to control and reduce OMPs dissemination in the environment. Thus, various types of biological wastewater treatment processes including activated sludge processes, biofilm processes, wetland and lagoon, and membrane bioreactor were analyzed for their OMP’s removal efficiencies. Findings demonstrated that advanced processes like membrane bioreactors (MBR) may not always outperform other low-costs biotechnologies in the treatment of OMPs (e.g., bisphenol A removal by activated sludge with anoxic and oxic zone, AS-AAO was 93% versus MBR at 89%). But rather, the removal efficiency will depend on pollutant properties and certain operational parameters such as hydraulic retention time, treatment capacity, and removal efficiency of total suspended solids.

Effects of nitrate reduction on the biotransformation of 1H-1,2,4-triazole: Mechanism and community evolution

Due to the refractory of 1 H-1,2,4-triazole (TZ), conventional anaerobic biological treatment technology is usually restricted by low removal efficiency and poor system stability. In this study, TZ biodegradation and nitrate reduction was coupled to improve the removal efficiency of TZ from polluted wastewater. Batch assay was performed with pure culture strain Raoultella sp. NJUST42, which was reported to have the capability to degrade TZ in our previous study. Based on batch assay result, complete removal of TZ could be achieved in the presence of nitrate, whereas only 50% of TZ could be removed in the control system. Long-term stability experiment indicated that the relative abundance of microorganisms (Bacteroidetes_vadinHA17, Georgenia, Anaerolinea, etc) was obviously enhanced under nitrate reduction condition. During long-term period, major intermediates for TZ biodegradation such as [1,2,4]Triazolidine-3,5-diol, hydrazine dibasic carboxylic acid and carbamic acid were detected. A novel TZ biotransformation approach via hydration, TZ-ring cleavage, deamination and oxidation was speculated. PICRUSt1 and KEGG pathway analyses indicated that hydration (dch), oxidation (adhD, oah, pucG, fdhA) of TZ and nitrate reduction (Nar, napA, nrfA, nirBK, norB, nosZ) were significantly enhanced in the presence of nitrate. Moreover, the significant enrichment of TCA cycle (gab, sdh, fum, etc.) indicated that carbon and energy metabolism were facilitated with the addition of nitrate, thus improved TZ catabolism. The proposed mechanism demonstrated that TZ biodegradation coupled with nitrate reduction would be a promising approach for efficient treatment of wastewater contaminated by TZ.

Removal of RNA viruses from swine wastewater using anaerobic membrane bioreactor: Performance and mechanisms

The effective removal of viruses from swine wastewater using anaerobic membrane bioreactor (AnMBR) is vital to ecological safety. However, most studies have focused only on disinfectants, whereas the capabilities of the treatment process have not been investigated. In this study, the performance and mechanism of an AnMBR in the removal of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic diarrhea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) are systematically investigated. The results show that the AnMBR effectively removes the four viruses, with average removal efficiencies of 1.62, 3.05, 2.41, and 1.34 log for HEV, PKoV, PEDV and TGEV, respectively. Biomass adsorption contributes primarily to the total virus removal in the initial stage of reactor operation, with contributions to HEV and PKoV removal exceeding 71.7 % and 68.2 %, respectively. When the membrane is fouled, membrane rejection dominated virus removal. The membrane rejection contribution test shows the significant contribution of membrane pore foulants (23–76 %). Correlation analysis shows that the surface characteristics and size differences of the four viruses contribute primarily to their different effects on biomass adsorption and membrane rejection. This study provides technical guidance for viral removal during the treatment of high-concentration swine wastewater using an AnMBR.

Nitrogen and phosphorus removal from synthetic aquaculture water through electrocoagulation

In this research, we utilized multivariate analysis to evaluate the efficient removal of nitrogen and phosphorus from synthetic aquaculture water using the electrocoagulation process. The elimination of nitrogen and phosphorus is a critical issue in various wastewater treatment plants and aquaculture systems, especially in instances of intensive or super-intensive cultivation. To avert the buildup of pollutants in the water, be it within internal recirculation systems or bodies of water receiving effluents from rearing tanks, it is imperative to employ treatment methodologies designed to effectively eliminate nitrogen and phosphorus nutrients. These nutrients have the potential to induce eutrophication in aquatic ecosystems. However, conventional biological treatment technologies can be ineffective, as they often only remove one pollutant or the other. Furthermore, the individual operations for these systems are complex and require substantial space. Electrocoagulation is a compact and promising technology for treating aquaculture water and effluents for raw nutrient removal. In this context, our findings showcase the simultaneous removal of both nitrogen and phosphorus through the electrocoagulation method. The best treatment was verified for the highest electrical current density (74 A. m-2), the shortest distance between electrodes (4 cm), and the lowest electrolysis time (50 min). In these conditions, the efficiency removal in ammonia nitrogen and total phosphorus were 30.5% and 100% respectively.&#x0D; Keywords: electrochemical treatment, eutrophication, water pollution control.

Effects of Hydrothermal Pretreatment and Anaerobic Digestion of Pig Manure on the Antibiotic Removal and Methane Production.

Whether advanced biological waste treatment technologies, such as hydrothermal pretreatment (HTP) integrated anaerobic digestion (AD), could enhance the removal of different antibiotics remains unclear. This study investigated the outcome of antibiotics and methane productivity during pig manure treatment via HTP, AD, and HTP + AD. Results showed improved removal efficiency of sulfadiazine (SDZ), oxytetracycline (OTC), and enrofloxacin (ENR) with increased HTP temperatures (70, 90, 120, 150, and 170°C). OTC achieved the highest removal efficiency of 86.8% at 170°C because of its high sensitivity to heat treatment. For AD, SDZ exhibited resistance with a removal efficiency of 52.8%. However, OTC and ENR could be removed completely within 30days. When HTP was used prior to AD, OTC and ENR could achieve complete removal. However, residual SDZ levels reduced to 20% and 16% at 150 and 170°C, respectively. The methanogenic potential showed an overall upward trend as the HTP temperature increased. Microbial analysis revealed the antibiotics-induced enrichment of specific microorganisms during AD. Firmicutes were the dominant bacterial phylum, with their abundance positively correlated with the addition of antibiotics. Methanobacterium and Methanosarcina emerged as the dominant archaea that drove methane production during AD. Thus, HTP can be a potential pretreatment before AD to reduce antibiotic-related risks in manure waste handling.

Performance of full-scale rural wastewater treatment plants in the reduction of antibiotic-resistant bacteria and antibiotic resistance genes from small-city effluents

The main objective of this study was to evaluate the performance of full-scale rural wastewater treatment plants (WWTPs) in the reduction of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from small-city effluents. Twenty full-scale WWTPs in rural Chile with different biological treatment technologies (vermifiltration (VF), activated sludge (AS) and biodisc (BD)) and disinfection treatments (chlorination (Cl) and UV irradiation (UV)) were monitored and studied in two campaigns: Campaign 1 (20 WWTPs) and Campaign 2 (6 WWTPs). In both campaigns, the rural WWTPs improved the water quality of the effluents very significantly (90%, 70%, and 40% reductions in TU, COD, and NH4+-N, respectively) and reduced ARB and ARG loads by 2–4 log units. All three biological treatments contributed to the final quality of the effluents, especially in terms of microbiological parameters, with statistically indistinguishable efficiencies between them. These results show the importance of rural WWTPs in improving the water quality of urban effluents while reducing microbiological risk and the spread of antibiotic resistance into the environment. The study demonstrates the utility of a non-centralized, self-managed wastewater treatment scheme that can be implemented in many sparsely populated areas around the world.

Microbial Ecology of Granular Biofilm Technologies for Wastewater Treatment: A Review.

Nowadays, the discharge of wastewater is a global concern due to the damage caused to human and environmental health. Wastewater treatment has progressed to provide environmentally and economically sustainable technologies. The biological treatment of wastewater is one of the fundamental bases of this field, and the employment of new technologies based on granular biofilm systems is demonstrating success in tackling the environmental issues derived from the discharge of wastewater. The granular-conforming microorganisms must be evaluated as functional entities because their activities and functions for removing pollutants are interconnected with the surrounding microbiota. The deep knowledge of microbial communities allows for the improvement in system operation, as the proliferation of microorganisms in charge of metabolic roles could be modified by adjustments to operational conditions. This is why engineering must consider the intrinsic microbiological aspects of biological wastewater treatment systems to obtain the most effective performance. This review provides an extensive view of the microbial ecology of biological wastewater treatment technologies based on granular biofilms for mitigating water pollution.

A novel method for identifying aerobic granular sludge state using sorting, densification and clarification dynamics during the settling process

Aerobic granular sludge is one of the most promising biological wastewater treatment technologies, yet maintaining its stability is still a challenge for its application, and predicting the state of the granules is essential in addressing this issue. This study explored the potential of dynamic texture entropy, derived from settling images, as a predictive tool for the state of granular sludge. Three processes, traditional thickening, often overlooked clarification, and innovative particle sorting, were used to capture the complexity and diversity of granules. It was found that rapid sorting during settling indicates stable granules, which helps to identify the state of granules. Furthermore, a relationship between sorting time and granule heterogeneity was identified, helping to adjust selection pressure. Features of the dynamic texture entropy well correlated with the respirogram, i.e., R2 were 0.86 and 0.91 for the specific endogenous respiration rate (SOURe) and the specific quasi-endogenous respiration rate (SOURq), respectively, providing a biologically based approach for monitoring the state of granules. The classification accuracy of models using features of dynamic texture entropy as an input was greater than 0.90, significantly higher than the input of conventional features, demonstrating the significant advantage of this approach. These findings contributed to developing robust monitoring tools that facilitate the maintenance of stable granular sludge operations.

Study on the degradation of triethylamine wastewater by catalytic ozone-biological coupled system of Ce-Fe@ZSM-5

Triethylamine (TEA) is an organic amine, due to the development of the pesticide industry, TEA wastewater volumes of yearly increasing, the poor biochemical performance and high toxicity. Therefore, we report a novel ozone catalyst as biological treatment technology by compounding Ce-Fe@ZSM-5 molecular sieve and domesticated activated sludge to construct a catalytic ozone-biodegradation coupling system. The low efficiency of ozone utilization was addressed by optimizing the stability and activity strength of the catalyst with a large specific surface area. The degradant rate of TEA reached 89.5 % versus 82 % of biological treatment and the elimination rate of TOC reached 71.5 %, which is 7.5 % increase the biological treatment of TEA. In order to efficiently degrade TEA and other organic amine compounds, the degradation pathway and mechanism of TEA were investigated. This research offered a theoretical foundation and prospective application for degradation of TEA.

Contrasting Distribution of Microbial Communities, Functional Genes, and Antibiotic Resistance Genes in Produced Water Treatment Plants with Different Treatment Technologies

A massive volume of produced water (PW) generated in the process of oil extraction must be treated effectively due to its threat to the ecosystems and human health. Different biological treatment technologies have been used in wastewater treatment plant (WWTP) systems to treat PW. However, their influence on treatment performance has not been investigated. In this study, three PW treatment plants (PWTPs) with different treatment technologies were compared in the following aspects: microbial community structure and assembly, functional genes, and the spread of antibiotic resistance genes (ARGs). The results indicated that different biological treatment technologies led to the variations in the diversity and composition of the microbial community. Phylogenetic bin-based null model analysis (iCAMP) revealed that different treatment technologies deterministically drove the assembly of microbial communities, especially the genera associated with the removal of petroleum hydrocarbons. The results of the metagenomic analysis showed that the genes related to the degradation of alkanes and aromatic hydrocarbons were the most abundant in PWTP3, suggesting it had the highest petroleum degradation potential. In addition, the highest abundance of ARGs in PWTP1 indicated the potential facilitation of ARG dissemination in activated sludge systems. Network analysis indicated that the dissemination of ARGs in the PWTPs might be mediated by transposases.

Characteristics and Comparison of Biofilm and Activated Sludge Sewage Treatment Technologies

Sewage treatment is a key environmental protection task and is of great significance to sustainable development. In this paper, biological filter method, rotating biological plate method, traditional push-flow activated sludge method and gradually reduced aeration method are selected to summarize and compare their principles, advantages and disadvantages, and removal objects. Biofilm method is similar to the principle of soil self-purification. It is a kind of aerobic biological treatment technology juxtaposed with activated sludge, and it is a fixed membrane process. The activated sludge is similar to the self-purification principle of water. It is an aerobic biological treatment method for sewage, removing dissolved and colloidal biochemical organic matter from the effluent, as well as suspended solids and other substances that can be adsorbed by activated sludge. It also removes some of the phosphorus and nitrogen. Both methods belong to wastewater biological treatment of suspended microorganisms in the water. They have their advantages, disadvantages and applicable conditions, so there is no competition between the two methods.

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.

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.

Biological Treatment of Industrial Wastewater

The objective of this study is to explore in depth the biological treatment technologies for industrial wastewater and to analyze their application and development with the aim of improving the efficiency of industrial wastewater treatment, reducing costs, and minimizing the adverse effects on the environment. Specifically, it includes: systematically summarizing and comparing the current common biological treatment technologies for industrial wastewater, analyzing their advantages and disadvantages, scope of application, and effectiveness, in order to improve the understanding and control of the biological treatment process. Biofilm treatment technologies include fluidized bed biofilm reactor (FBBR), membrane biofilm reactor (MBfR), moving bed biofilm reactor (MBBR), and rotating biological contactor (RBC). Further research and innovation are needed to improve treatment efficiency, reduce energy consumption and anaerobic treatment, control membrane pollution and degrade difficult-to-biodegrade substances.