Alternative Wastewater Treatment Research Articles

Effect of Photocatalytic Pretreatment on the Membrane Performance in Nanofiltration of Textile Wastewater

Traditional methods like biological treatment, flocculation-coagulation, adsorption, and advanced oxidation are commonly employed for textile wastewater treatment, but their sustainability is hindered by issues such as the adverse impact of textile wastewater on microorganisms and the requirement for substantial chemical usage. In response to increasingly stringent legal discharge standards, membrane technologies are emerging as prominent alternatives for effective textile wastewater treatment. The application of photocatalysis as a pretreatment to improve effluent quality and treatment performance has shown effective results in the treatment of textile wastewater by nanofiltration (NF). However, innovative solutions are needed to improve the efficiency of UV photocatalytic reactors. Here, the TiO2/halloysite nanotube (HNT) photocatalyst was shown to completely remove dyes under UV illumination. Two wastewater samples from photocatalytic (PC) pretreatment were treated using innovative NF membranes with different contents. The study examined the impact of PC pretreatment on the flux of wastewater from a textile factory heat recovery tank, which increased from 18.32 to 27.63 L/m2.h. The membranes achieved > 98% removal in COD, while bare membrane achieved 95% removal in conductivity. The addition of s-DADPS as monomer and HNT as nanoparticles to the membranes with different compositions affected the cross-linking in the TFC layer. During the tests conducted on the water extracted from the dyeing tank, the color was completely eliminated without any loss of flux. Additionally, improvements in COD removal were observed.

Use of Plant-Based Coagulants Sorghum Bicolor and Trifolium Repens as Future Alternatives for Textile Wastewater Treatment Based on Computational Model

Sorghum bicolor and Trifolium repens extracts as plant coagulants can be used for wastewater treatment instead of chemical coagulants. This study investigates the effects of pH and coagulant dose on COD and turbidity reduction by natural coagulants. In the optimum treatment conditions of 100 mg/L coagulant dose and pH 7, high turbidity (81.34%), and COD reduction (62%) (compared with alum and FeCl3) were obtained. The percentage of COD reduction is higher in Trifolium repens than the other plant coagulant, and the percentage of turbidity reduction is higher in Sorghum bicolor. FT-IR spectra were performed on the plant extracts to identify the existing factors in active extracts. Also, outlet COD and turbidity values can be predicted and calculated according to computational equation in similar treatment systems. It should be mentioned that the only applied solvent for extracting the natural coagulant seeds was distilled water, and none of the other solvents such as NaCl and NaOH were used. According to the results, the characteristics of the treated effluents by the plant extracts make them appropriate alternatives for textile wastewater treatment.

Characterization and Proposal of Technologies for The Treatment of Domestic Sewage in Ilha Grande Bay – RJ

Objective: To characterize the situation of sanitary wastewater discharge in the hydrographic basins draining into the Baía da Ilha Grande (BIG) and to propose wastewater treatment alternatives based on the literature on decentralized solutions. Theoretical framework: The BIG has been experiencing negative environmental impacts due to the urbanization process in the region, mainly due to the irregular discharge of domestic wastewater into the environment. Method: The methodology was developed in two stages, with stage 1 involving data collection from available data in the 2017 Wastewater Atlas, and stage 2 focusing on identifying the most appropriate treatment technologies for this study from the fifteen options evaluated. Results and conclusion: The characterization revealed that municipalities within the BIG are already using decentralized solutions for domestic wastewater treatment, albeit below the national average coverage rates (18-54%). The five most promising technologies identified were Septic Tanks, Compact UASB, Biodigesters, Compartmentalized Anaerobic Reactors, and Integrated Biosystems. It is concluded that the communities have a sanitation deficit and show potential for implementing decentralized solutions. Implications of the research: The study helped develop strategies for decision-makers to select the most appropriate wastewater treatment technologies to meet local needs. It also served as a model for scientific studies in other locations. Originality/value: This study aligns with the Sustainable Development Goals (SDGs), particularly SDG 6, by presenting decentralized solutions as a promising pathway to universalizing household wastewater treatment in developing countries.

Biodegradability and bioavailability of dissolved substances in aquaculture effluent: Performance of indigenous bacteria, cyanobacteria, and green microalgae

Aquaculture is a controlled aquatic farming sector and one of the most important human food sources. Fish farming is one of the predominant, fast-growing sectors that supply seafood products worldwide. Along with its benefits, aquaculture practices can discharge large quantities of nutrients into the environment through non-treated or poorly treated wastewater. This study aims to understand the nutrient composition of fish wastewater and the use of indigenous bacteria, cyanobacteria, and microalgae as an alternative biological treatment method. Wastewater samples from a local fish farming facility were collected and treated using six different species of cyanobacteria and microalgae include Chroococcus minutus, Porphyridium cruentum, Chlorella vulgaris, Microcystis aeruginosa, Chlamydomonas reinhardtii, and Fischerella muscicola. All the samples were incubated for 21 days, and the following parameters were measured weekly: Chemical oxygen demand (COD), phosphate, total dissolved nitrogen, and dissolved inorganic nitrogen. In addition, dissolved organic nitrogen (DON), bioavailable DON (ABDON), and biodegradable DON (BDON) were calculated from the mass-balance equations. Colorimetric and digestive methods were used for the parameter measurements. The results showed that C. reinhardtii reduced the soluble COD concentration by 74.6 %, DON by 94.3 %, and phosphorous by more than 99 %. Moreover, M. aeruginosa, and C. minutus significantly reduced inorganic nitrogen species (>99 %). This alternative fish wastewater treatment method was explored to gain insight into fish wastewater nutrient composition and to create a sustainable alternative to conventional fish wastewater treatment methods.

Seaweed-based biosorbent for the removal of organic and inorganic contaminants from water: a systematic review

Inadequately treated or untreated wastewater contributes substantially to the discharge of undesirable and hazardous substances into aquatic environments. Serious concerns are raised when certain pollutants become persistent and bioaccumulative upon release into the environment. Despite the existence of alternative wastewater treatment technologies, adsorption has consistently demonstrated its efficacy in the treatment of wastewater originating from diverse industrial sources. Adsorption is selected as the optimal method due to its numerous benefits, which include greater efficacy, reduced cost, and convenient accessibility in comparison to alternative treatments. Biosorption using naturally occurring seaweeds can, however, remove contaminants from a variety of sources, including heavy metals, nitrogen, phosphorus, and phenolic compounds, and dyes from the paper, textile, and printing industries. Biosorption utilizing seaweed has surfaces as a feasible substitute for existing technologies in the effective elimination of these pollutants from effluent on account of its environmentally sustainable nature, readily available resources, and cost-effectiveness. An economical adsorbent known as seaweed is examined in this article in order to remove contaminants from effluent. In an extensive table, the application of seaweed in effluent treatment is detailed. The majority of studies, according to published research, have utilized simulated wastewater; biosorption using seaweed to remediate actual wastewater has received less attention.

(Invited) Evaluating Urban Water-Energy Systems Based on UN Sustainable Development Goals (SDGs)

Evaluating Urban Water-Energy Systems Based on UN Sustainable Development Goals (SDGs) Water, food, and energy are three of the major resource issues facing the world today. To help address these issues, urban wastewater is now being considered as a renewable resource than as a waste- a resource for water, for energy, and fertilizers. It is now well recognized that the traditional urban wastewater infrastructure needs to be re-engineered for improved environmental, social, and economic sustainability by minimizing the energy input for treating the wastewaters and by recovering water, energy, and fertilizers from the wastewater for beneficial reuse. In recent years, several alternate technologies have been proposed to take advantage of the water-energy nexus in urban wastewater infrastructure systems. This paper presents a case study evaluating sustainability of four urban water-energy nexus based on the 17 United Nations Sustainable Development Goals (SDGs) that have been unanimously endorsed by all 193 member countries. A multi-criteria decision making (MCDM) approach is used in this study to evaluate the four alternate urban water-energy systems in terms of 30 criteria spanning environmental, social, and economic sustainability. The 30 criteria selected here were derived from the 17 SDGs. The MCDM approach was selected in this study because of its ability to handle quantitative and qualitative criteria and rank the options on a numerical scale. The four wastewater treatment alternatives were evaluated under 12 different scenarios considering high/low priorities of decision-makers towards six different water-energy nexus attributes (pathogen removal, energy consumption, gaseous emission, resource recovery, footprint, and past records).

Photosynthetic Bacteria as an Alternative Wastewater Treatment in Freshwater Aquarium Fish Set Up

Waste produced from aquaculture ultimately hampered the water quality and growth performance of species cultured. Therefore, the potential exploitation of photosynthetic bacteria (PSB) from aquaculture waste was investigated to treat the wastewater in the fish culture. In this study, the wastewater was collected from a fishpond and cultured in sunlight-exposed sterile bottles for 14 days. In the water additive experiment, five treatments (in a 30 cm3 aquarium) were prepared namely cultured PSB (T1), aquatic plant hornwort (T2), aquatic plant salvinia (T3), positive control (P), and negative control (N). Five individuals of Hyphessobrycon herbertaxelrodi (2.5±0.5 cm length) were placed in each treatment and reared for 30 days. Meanwhile, for the wastewater treatment, four treatments (in a 30 cm3 aquarium) were prepared namely wastewater from the hatchery fishpond (S1), wastewater from the hatchery fish tank (S2), positive control (P), and negative control (N). The results obtained indicate that T1 treatment significantly improved and maintained the water quality as compared to other treatments. The results showed the amount of ammonia and nitrite in S1 and S2 supplied with T1 for 30 days gradually decreased from day 1 until day 18. While zero amount of ammonia and nitrate was acquired from day 21 until day 30 of the wastewater experiment. The treatment with PSB showcased the bacteria's ability to utilize and absorb nutrients, thereby maintaining and improving water quality. The potential use of beneficial bacteria in the culture system can accelerate the nitrogen cycle for a sustainable way of wastewater management.

A multi-criteria decision framework for circular wastewater systems in emerging megacities of the Global South

Lima faces increasing water stress due to demographic growth, climate change and outdated water management infrastructure. Moreover, its highly centralized wastewater management system is currently unable to recover water or other resources. Hence, the primary aim of this study is to identify suitable wastewater treatment alternatives for both eutrophication mitigation and indirect potable reuse (IPR). For eutrophication mitigation, we examined MLE, Bardenpho, Step-feed, HF-MBR, and FS-MBR. For IPR, we considered secondary treatment+UF + RO + AOP or MBR + RO + AOP. These alternatives form part of a WWTP network at a district level, aiding Lima's pursuit of a circular economy approach. This perspective allows reducing environmental impacts through resource recovery, making the system more resilient to disasters and future water shortages. The methods used to assess these scenarios were Life Cycle Assessment for the environmental dimension; Life Cycle Costing for the economic perspective; and Multi-Criteria Decision Analysis to integrate both the quantitative tools aforementioned and qualitative criteria for social and techno-operational dimensions, which combined, strengthen the decision-making process. The decision-making steered towards Bardenpho for eutrophication abatement when environmental and economic criteria were prioritized or when the four criteria were equally weighted, while HF-MBR was the preferred option when techno-operational and social aspects were emphasized. In this scenario, global warming (GW) impacts ranged from 0.23 to 0.27 kg CO2eq, eutrophication mitigation varied from 6.44 to 7.29 g PO4− equivalent, and costs ranged between 0.12 and 0.17 €/m3. Conversely, HF-MBR + RO + AOP showed the best performance when IPR was sought from the outset. In the IPR scenario, GW impacts were significantly higher, at 0.46–0.51 kg CO2eq, eutrophication abatement was above 98 % and costs increased to ca. 0.44 €/m3.

Phytoremediation: A Shift Towards Sustainability for Dairy Wastewater Treatment

AbstractDairy processing industries have emerged as the most swiftly evolving sectors with excessive wastewater generation containing proteins, fat, oils, greases (FOGs), etc. As there is rising strain on energy usage and dependence on water resources, sustainable research focuses on reduction in wastewater generation and developing value‐added goods. An effective and widely explored sustainable technique for treating wastewater is phytoremediation, a plant‐based process. This review aims to analyze phytoremediation as a sustainable alternative for dairy wastewater treatment. It initially briefs about dairy wastewater characteristics and treatment alternatives and discusses constructed wetlands and hydroponic system in detail with mechanism insights and influenced process parameters. Interconnected technologies with phytoremediation and their impact on contaminant transformations, nutrient reuse, and detoxification of pollutants are encompassed. Also, resource recovery and biomass utilization, feedstock enrichment along with the future prospects of integrated hydroponic systems for achieving sustainability with efficient resource recovery are featured.

Synthesis of Bamboo-based Activated Carbon through Physico-chemical Activation for Coal-runoff Wastewater Treatment

Bamboo-based activated carbon (BAC) has been successfully synthesized through a physico-chemical technique. The characteristics of BAC were investigated using Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR), and X-Ray Diffraction (XRD). Evaluating BAC performance on coal-runoff wastewater was carried out by varying contact times and adding low-level alum on remediation of pH and Total Suspended Solid (TSS). The results confirm that BAC performs well in stabilizing pH, indicated by the neutral pH, after 10 minutes of interaction. The TSS with BAC treatment and 1% BAC-Alum combination reduced the TSS value from 880 mg/L to levels below the threshold for wastewater quality standards, 387 mg/L and 73 mg/L, respectively. This combination can be an alternative coal-runoff wastewater treatment technique for better environmental quality.

Model-based comparison of biological wastewater and sludge treatment combinations for nutrient removal, sludge and biogas production

One of the strategies for reducing the potential environmental and health-related risks associated with wastewater treatment sludge is to select treatment options that would minimize its production while using its beneficial products and meeting effluent discharge standards. In this regard, simulation models can aid in estimating treatment performance, sludge production, and biogas formation. This study evaluates effluent concentrations focusing on nutrients, sludge production, and biogas generation rates for various combinations of wastewater and sludge treatment alternatives for varying strengths of domestic wastewater. Overall, 105 scenarios were simulated for three different wastewater strengths for 35 treatment schemes. Bardenpho-5 (B5) was superior over A2O (A2) in removing nitrogen and phosphorous. Adding primary sedimentation to A2 and B5 models improved sludge and in turn biogas production. Effluent total phosphorus (TP) was usually higher in scenarios with anaerobic sludge digestion. However, struvite precipitation following anaerobic digestion helped reduce total nitrogen (TN) and TP effluent concentrations for all wastewater treatment technologies. Sludge production amounts ranged between 2865 kg/day to 38,709 kg/day (total solids) for an influent flow rate of 100,000 m3/day. Sludge production rates were relatively insensitive to sludge treatment alternatives for extended aeration (EA) compared to conventional activated sludge (AS), A2, A/O (AO), and B5. Generally, the impact of a sludge treatment option was significant for wastewater treatment technologies with higher waste sludge production. Thermal hydrolysis followed by anaerobic digestion provided the lowest sludge production and significantly improved the biogas production.

Facile surface-controlled synthesis of phytic acid-facilitated calcium carbonate composites for highly efficient ferric ion adsorption and recovery from rust

This work presents a simple synthesis of calcium carbonate (CaCO3)-based composites designed for the efficient adsorption of ferric ions (Fe3+) from solution, and specifically applied for Fe3+ recovery from rust. The strategy involves coordinating phytic acid (PA) with calcium ions (Ca2+) and coprecipitation with carbonate ions (CO32−) at room temperature to form phytate-CaCO3 (Ph-CC) composites. The obtained composites exhibited a robust mesoporous crystal structure with numerous phosphate groups of phytate functionalized on CaCO3 microparticles. The surface properties of the composites were optimized by adjusting the molar ratio (x) of PA:Ca2+ in synthesis. The Ph-CC0.10 composite (x = 0.10), with the highest specific surface area (99.56 m2/g), demonstrated exceptional Fe3+ adsorption (>99% efficiency in 80 min). The adsorption process followed the pseudo-second-order and Langmuir isotherm models, indicating monolayer coverage. Impressively, the maximum adsorption capacity reached 1385.85 mg/g, surpassing that of previously reported adsorbents. Thermodynamic studies confirmed a spontaneous and exothermic adsorption process. The superior Fe3+ adsorption of the composite was attributed to electrostatic and chelation interactions, with partial ion exchange. Furthermore, the Ph-CC0.10 composite effectively captured Fe3+ from rust dissolution in an acidic solution (pH 3) under sonication at 35 kHz for 60 min. These results highlight the potential use of the developed composites in mitigating environmental pollution and transforming waste materials into valuable sources. Therefore, Ph-CC composites are promising alternatives for wastewater treatment and metallurgical applications.

Sequestering of Heavy Metals by Bio-sorption

Fresh water represents 3% of water assets on the Earth. Human and mechanical exercises produce and release squanders containing overwhelming metals into the water assets making them inaccessible and undermining human wellbeing and the environment. Regular strategies for the evacuation of metal particles, for example, compound precipitation and layer filtration are very costly while treating a lot of water, wasteful at low groupings of metal (inadequate metal expulsion) and create enormous amounts of slop and other dangerous items that require cautious removal. Bio-sorption and bioaccumulation are ecofriendly options. These elective strategies have points of interest over customary techniques. Plentiful characteristic materials like microbial biomass, agro-squanders, and modern results have been recommended as potential biosorbents for overwhelming metal evacuation because of the nearness of metal-restricting practical gatherings. Biosorption is affected by different procedure parameters, for example, pH, temperature, beginning grouping of the metal particles, biosorbent portion, and speed of fomentation. Likewise, the biomass can be adjusted by physical and substance treatment before use. The procedure can be made affordable by recovering and reusing the biosorbent in the wake of expelling the overwhelming metals. Different bioreactors can be utilized in biosorption for the expulsion of metal particles from enormous volumes of water or effluents. The ongoing improvements and the future degree for biosorption as a wastewater treatment alternative are talked about

Microwave assisted zirconium oxide based catalytic activation of persulfate for methyl orange dye degradation

In this investigation, zirconium oxide (ZrO2) based activation of persulfate (PS) under microwave (MW) irradiation for methyl orange (MO) dye degradation was studied. ZrO2 was synthesized using facile hydrothermal method and it was characterized via XRD, FTIR, SEM, and TGA techniques. Subsequently, MW/ZrO2/PS experiments were conducted to explore the effect of ZrO2 dosage (0–1.5 g/L), initial MO concentration (15–250 mg/L), MW reactor temperature (60–90 ℃), MW power (240–700 W), PS dosage (50–250 mg/L), and presence of NaCl (0–5000 mg/L) on MO removal at pH ~ 7. Under the optimal conditions (ZrO2 ~ 0.5 g/L, MO concentration ~ 25 mg/L, MW temperature ~ 90 ℃, MW power ~ 560 W, and PS dose~250 mg/L), 99 % of MO removal and 85.9 % of TOC removal were observed. Moreover, the toxicity of the initial sample was reduced by 72.9 %. Interestingly, the catalytic oxidation of MO was not affected due to the presence of NaCl. Radical studies confirmed that SO4−⦁ radical was the major active species responsible for MO degradation. Subsequently, the central composite design (CCD) approach was used to find out the interaction effects between MO concentration (10–250 mg/L), PS dosage (50–500 mg/L), and MW treatment time (5–20 min) on MO removal. The CCD based response surface model was found to be significant and reliable (p < 0.0001). Moreover, the chemical cost and energy cost for MW/ZrO2/PS experiments under optimized condition was estimated as $22.5 and $30.3 per kg of MO removal. Overall, transition metal-based PS activation under MW irradiation could be one of the potential alternatives for dye wastewater treatment.

Development of microbial fuel cell for wastewater treatment and electricity generation using domestic wastes

Background: The energy crisis is a growing problem around the world, requiring the creation of alternative energy sources that can generate less carbon dioxide and benefit the ecosystem. Reutilization of wastewater is becoming the emerging energy solution. Wastewater contains a large amount of organic matter that can be oxidized in microbial fuel cells (MFCs) to produce electricity. MFCs use biodegradable materials to create energy in the presence of microorganisms. Methods: Purposive sampling technique was employed to collect samples from critical polluting sources. The samples were certainly maintained in a refrigerator at 4°C. Several mixes for sample were prepared and tested analytically- for physio-chemical and bacteriological characterizations of each substrate status at pre- and post-treatment stages. Electricity generating capacity of MFCs that employing different substrates was investigated experimentally using batch reactors. The cross-sectional methodology was employed to study possible power generation. Results: The maximum voltage output of 118.93, 144.84, and 89.76 mV were produced keeping the resistance unlimited for MFC1 (urine substrate), MFC2 (blackwater substrate), and MFC3 (graywater substrate), respectively. MFC that utilized graywater as a substrate brought the tiniest quantity of electricity; however, it stood the most stable. The highest COD reduction (65.83%) in the process was reported in urine substrate and the highest BOD5 removal (69.18%) was reported in black water substrate. Conclusion: The experimental results provided a promising indication of MFCs viability, providing hope for future power generation and alternative wastewater treatment option in developing countries.

Environmental performance of constructed wetland planted with monocultures and polycultures for wastewater treatment

The effects of culture systems and seasonality on the environmental impact of constructed wetlands (CWs) remain understudied. This study aims to quantify the environmental impact of common and ornamental plants in a pilot-scale horizontal subsurface flow (HSSF) CW planted with monocultures and a polyculture. Eight scenarios were evaluated, differentiated by plant type, culture system, and season (warm season, cold season). Environmental performance was evaluated using the life cycle assessment (LCA) methodology. The environmental impact index (ƐP), based on eutrophication reduction (kgP removed), and net environmental benefit (NEB) indicators were also calculated. The results showed that a CW planted with polycultures reduced FE by 5–17% compared to those planted in monocultures. However, the polyculture had the highest environmental impact in the GW category, up to 1.5–9 times higher than that of monocultures. Furthermore, there was better performance in the cold season in all scenarios. Specifically, NEB showed an environmental benefit for freshwater eutrophication and a negative benefit for global warming. The ƐP indicator was inversely proportional to the elimination of phosphorus, with the polyculture CW reaching the highest values of 3399 kgCO2eq/kgP removed in the warm season. The assessment of environmental impact patterns could support the development of strategies for better environmental performance of CWs, with polycultures used as an alternative wastewater treatment.

Use of Plant-Based Coagulants Sorghum Bicolor and Trifolium Repens as Future Alternatives for Textile Wastewater Treatment Based on Computational Model

Sorghum bicolor and Trifolium repens extracts as plant coagulants can be used for wastewater treatment instead of chemical coagulants. This study investigates the effects of pH and coagulant dose on COD and turbidity reduction by natural coagulants. In the optimum treatment conditions of 100 mg/L coagulant dose and pH 7, high turbidity (81.34%), and COD reduction (62%) (Compared with Alum and FeCl3) were obtained. The percentage of COD reduction is higher in Trifolium repens than the other plant coagulant and the percentage of turbidity reduction is higher in Sorghum bicolor. FT-IR spectra were performed on the plant extracts to identify the existing factors in active extracts. Also, outlet COD and turbidity values can be calculated according to computational equation in similar treatment systems where using the same plant coagulants. It should be mentioned that the only applied solvent for extracting the natural coagulant seeds, was distilled water and none of the other solvents such as NaCl and NaOH were used. According to the results, the characteristics of the treated effluents by the plant extracts make them appropriate alternatives for textile wastewater treatment.

Assisted-enzymatic hydrolysis vs chemical hydrolysis for fractional valorization of microalgae biomass

Despite the interest in the utilization of photobioreactors as an alternative wastewater treatment, the research about posterior recovery and valorization of nutrients accumulated in the biomass is still limited. This work compared several hydrolysis methods for the recovery of proteins and carbohydrates from the biomass grown in a photobioreactor treating swine wastewater. Ultrasound-assisted and microwave-assisted enzymatic hydrolysis at mild conditions and chemical methods at different temperatures (40, 60, 120ºC) were applied to the microalgae and bacteria biomass. Alkaline hydrolysis provided the greatest peptide recoveries, increasing with temperature up to a maximum of 81%, but with very small peptide sizes in all temperature range. Acid hydrolysis provided the highest carbohydrate recoveries (60.7% at 120ºC) but degraded proteins, even at mild temperatures. Protein degradation did not vary with temperature in each chemical hydrolysis, obtaining similar peptide sizes in all temperatures, while carbohydrate losses were higher at lower temperatures. Ultrasound-assisted enzymatic extraction recovered 43.6% of the initial proteins as large peptides (up to 135 kDa) with the highest peptide purity (46.7%). Microwave-assistance increased the carbohydrate solubilization of enzymatic hydrolysis, achieving yields of 73% of xylose, but with significant losses.

Use of natural fibers in alternative wastewater treatment technologies, aiming at a more sustainable production: A review

The most worrisome issues today are the excessive production of solids in wastewater and the discharge of wastewater containing toxic components. Despite current environmental legislation, there are still difficulties in treating wastewater and properly disposing of the waste generated in the various stages of the production process to avoid inadequate and premature disposal that may pollute the environment. As a result, techniques are being developed to reuse wastewater differently, and in this scenario, natural fibers can be used to treat wastewater through an adsorption-based technique. Thus, this research has been developed from an exploratory bibliographic survey carried out according to scientific papers that used natural fibers as bioadsorbents in Scopus, ScienceDirect, Web of Science, and Capes databases. VOSviewer® software was used to create a cluster map to analyze the correlation between citations of selected papers. It was observed an increase in the number of research on the above topic over the years, especially in 2021. The most used natural fibers were plant-based, mostly cellulose. When evaluating the scientific contribution by country, Malaysia, India, and China were the most relevant. Brazil ranked fourth. Therefore, even with legislation on wastewater disposal and targets for the 2030 wastewater treatment plan, some countries are lagging in alternative techniques for the use of natural fibers in adsorption processes.

Enhancement of biogranules development using magnetized powder activated carbon.

Biogranulation has emerged as a viable alternative biological wastewater treatment approach because of its strong biodegradability potential, toxicity tolerance, and biomass retention features. However, this process requires a long duration for biogranules formation to occur. In this study, magnetic powder activated carbon (MPAC) was used as support material in a sequencing batch reactor to enhance biogranules development for wastewater treatment. Two parallel SBRs (designated R1 and R2) were used, with R1 serving as a control without the presence of MPAC whileR2 wasoperated with MPAC. The biodegradability capacity and biomass properties of MPAC biogranules were compared with a control system. The measured diameter of biogranules for R1 and R2 after 8weeks of maturation were 2.2mm and 3.4mm, respectively. The integrity coefficient of the biogranules in R2 was higher (8.3%) than that of R1 (13.4%), indicating that the addition of MPAC improved the structure of the biogranules in R2. The components of extracellular polymeric substances were also higher in R2 than in R1. Scanning electronic microscopy was able to examine the morphological structures of the biogranules which showed there were irregular formations compacted together. However, there were more cavities situated in R1 biogranules (without MPAC) when compared to R2 biogranules (with MPAC). Dye removal reached 65% and 83% in R1 and R2 in the post-development stage. This study demonstrates that the addition of MPAC could shorten and improve biogranules formation. MPAC acted as the support media for microbial growth during the biogranulation developmental process.