Organic Matter Removal Research Articles

Ozonation process at neutral pH integrated with anaerobic treatment system to methylparaben removal

The incomplete removal of emerging pollutants, such as parabens, from wastewater effluents represents a major pathway for their release into the environment. The development of advanced technologies integrated into well-known conventional systems is a solution. Advanced oxidative processes (AOP), such as ozonation and its combinations, are technologies based on the generation of hydroxyl radicals (HO•) capable of removing these pollutants, representing an alternative solution to this problem. Therefore, the present study aimed to investigate the ozonation process combined with hydrogen peroxide (O3/H2O2) in the treatment of anaerobic effluent post-treated by a real-scale upflow anaerobic sludge blanket (UASB) reactor, enriched with methylparaben (MeP). The study was conducted under optimized conditions and at neutral pH of the effluent. To investigate the influence of variables, as ozone concentration, hydrogen peroxide concentration, pH and time, a 24 Factorial experimental design followed by a 22 Doehlert optimization design was implemented. The optimal degradation occurred with 25.0 mg L−1 of O3 and 30.0 mg L−1 of H2O2 at neutral effluent pH, achieving a removal efficiency of 71.6 % after 60 min and 85.5 % after 120 min. The optimized O3/H2O2 process after 60 min achieved a 95.0 % removal of organic matter by biochemical oxygen demand (BOD), reducing the initial concentration from 138 mg L−1 to 7 mg L−1. Acute toxicity test with Artemia salina and Lactuca sativa, indicated an absence of toxicity (TU < 0.4). The findings of this study indicate the positive efficiency of combining post-UASB effluent treatment with O3/H2O2 processes for the removal of methylparaben.

Examining how media age affects organic matter removal in activated carbon filtration

AbstractWater samples from Waiora Drinking Water Treatment Plant in New Zealand were analyzed using excitation‐emission matrix fluorescence spectroscopy (EEMS) and parallel factor (PARAFAC) analysis to evaluate organic matter removal across the plant. The assessment also included the individual granular activated carbon (GAC) filters since the filters had varying media ages due to partial media replacement over a 10‐month period, presenting a unique assessment opportunity. PARAFAC analysis identified humic‐like, tyrosine‐protein‐like, and tryptophan‐protein‐like components representing fluorescent dissolved organic matter groups. The humic‐like component strongly correlated with total organic carbon (TOC) concentration and removal was significantly influenced by filter media age. However, protein‐like components had minimal TOC correlation and were not effectively removed by the overall plant treatment irrespective of filter media age. These findings have implications for disinfection, taste and odor, and bacterial regrowth and require an improved media replacement strategy. Further study of the protein‐like components is required.

Development of a γ-Al2O3-Based Heterogeneous Fenton-like Catalyst and Its Application in the Advanced Treatment of Maotai-Flavored Baijiu Wastewater

Heterogeneous Fenton technology was employed for the advanced treatment of Maotai-flavored Baijiu wastewater. Novel catalysts were prepared by loading different active ingredients (Mn, Fe, and Cu) on γ-Al2O3 using an impregnation method. The effects of active ingredient, reaction time, initial pH, H2O2 dosage, catalyst dosage, and other factors on the reaction were examined. The properties of the new catalysts were analyzed using BET analysis, XPS, and SEM. Moreover, the mechanisms of Fenton-like oxidation and its reaction kinetics were explored through experiments and analyses including GC–MS and intermediate active species scavenging by tertiary butyl alcohol (TBA) and/or para-benzoquinone. The results revealed that the most effective removal of organic matter was achieved with a Mn-Fe/Al (2:1 wt%) catalyst dosage of 30 g/100 g water, pH of 5.0, H2O2 dosage of 0.3 g/L, and reaction time of 60 min; the effluent COD value was 12 ± 1 mg/L, and the degradation rate was 65.7 ± 3%, approximately 14% higher than that of the conventional Fenton catalyst under similar conditions; moreover, the catalytic efficacy remained high after seven cycles. Kinetic analysis indicated that the heterogeneous Fenton oxidation reaction followed a third-order kinetics model, with R2 = 0.9923 and K = 0.0006 min−1.

Mixotrophic aerobic denitrification enhanced by inorganic electron donor: Novel insights into iron valence and nirS-type denitrifying bacterial community model

Nitrogen pollution was the main factor leading to reservoir eutrophication. The removal of low-concentration nitrate pollutants in water source reservoirs is an international problem to be solved. Insufficient organic electron donors in natural reservoir are a crucial limiting factor for in situ denitrification. Microbial mixotrophic aerobic denitrification using iron as the assisted electron donor is a potential pathway to treat micropolluted water bodies. The iron/activated carbon (IAC) was used to be an assisted electron provider to advance the mixotrophic aerobic denitrification performance of denitrifying bacterial community in micro-polluted reservoir water. Upon adding IAC into the reactors, the total nitrogen (TN) reduction capacity improved >41.10 %. A slight increase in organic matter removal efficiency observed in the IAC reactors compared to the control reactors. High-throughput sequencing revealed that IAC altered the richness, and co-occurrence of denitrifying bacterial community, further advancing nitrate transformation and removal. The relative abundant of Thauera, Dechloromonas, Cupriavidus, Alicycliphilus, and Azoarcus increased and presented predominant in the IAC reactors. Meanwhile, network analysis, niche width model, neutral community model, and species abundance distribution supported this finding. The Jinpen reservoir (JP; 34°32'38" N, 107°53'53" E, located in Xi’an, North China) and Xikeng reservoir (XK; 34°32'38" N, 107°53'53" E, located in Shenzhen, South China) raw water treatment experiments demonstrated excellent TN (> 60 %) and organic matter removal efficiencies (> 44 %).

Evaluation of low-cost carbon/metal electrodes as cathodes and anodes in sediment microbial fuel cells

In the present study, influence of different anode and cathode materials including carbon felt, carbon cloth, and several metal electrodes with or without carbon cloth covering on sediment microbial fuel cell (SMFC) performance was investigated. Results suggested that stainless steel poorly performed as cathode electrode whereas it exhibited reasonable performance as anode. In SMFCs with carbon felt cathode, anodes including 400 series stainless steel mesh and 300 series stainless steel plate, both covered with carbon cloth, led to higher maximum power densities of 88 and 87 mW/m−2, respectively, compared with carbon felt, carbon cloth, 400 series stainless steel mesh, 300 series stainless steel mesh covered with carbon cloth, and copper plate covered with carbon cloth (power densities of 40, 74, 53, 68, and 47 mW/m−2, respectively). They also resulted in higher loss on ignition (LOI) removals of 9.4 % and 8.7 %, respectively. Cyclic voltammetry results showed that stainless steel plate covered with carbon cloth produced the highest redox current that was two times that of the carbon cloth. In addition, electrochemical impedance spectroscopy indicated lower charge transfer resistance in the SMFC with anodes including 400 series stainless steel mesh (20.6 Ω) and 300 series stainless steel plate (25.7 Ω), both covered with carbon cloth, compared to other anode materials. These findings suggest that stainless steel electrodes covered with carbon cloth provide SMFCs with improved electrochemical characteristics that enhance their electricity production and organic matter removal.

Performance of Chitosan/Carbon Nanotube-Coated Ultrafiltration Membranes for Natural Organic Matter Removal from Drinking Water

The objective of this study is to improve the filtration efficiency of commercially available polyethersulfone (PES) ultrafiltration (UF) membranes, with a specific focus on removing natural organic matter (NOM) and preventing membrane fouling. The modification of UF membranes was accomplished by utilizing chitosan/multi-walled carbon nanotubes (CS/MWCNT-OH) and employing both dip and spin coating techniques. The membrane surface morphologies were evaluated using the Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Energy-Dispersive X-ray Spectroscopy (EDX) techniques. Tests were carried out to assess the effectiveness of the membranes in a laboratory-scale system using two primary water sources from Istanbul, specifically the Melen River and Terkos Lake. Total organic carbon (TOC), UV254 absorbance, turbidity, and trihalomethane formation potential (THMFP) were all measured as part of a thorough analysis. The surface morphology investigations verified the effective deposition of MWCNT-OH nanoparticles onto the membrane surface. This was corroborated by the reduction in the water contact angle, showing an improvement in the hydrophilicity of the membrane. The modified membranes demonstrated much higher TOC removal rates compared to the original membranes. Specifically, the removal efficiencies for Melen River and Terkos Lake were 37.14% and 56.86%, respectively. Nevertheless, the alteration of the surface led to a decline in membrane flux as a result of the concurrent drop in pore size. To summarize, the results of this work highlights the considerable capability of surface modification using CS/MWCNT-OH to improve the performance and antifouling characteristics of commercial PES UF membranes.

Evaluating small‐scale harvesting disturbance to the forest soil in Mediterranean beech high forests

AbstractEuropean beech (Fagus sylvatica L.) forests in Central and Southern Italy are managed applying the shelterwood system. Prior to the regeneration cut, it is common to apply 2–3 thinning interventions, aiming to obtain mostly firewood, considering the low dimension and poor quality of the stems. These interventions are usually carried out by local forest enterprises relying on a low or medium level of mechanization (small‐scale forestry). In particular, the short wood system is applied, thus processing the logs to 1 m length and extracting them with forestry‐fitted farm tractors equipped with forwarding bins. Despite the large application of this harvesting system in the Mediterranean forestry, no information is available in the literature about its possible disturbance to the forest soil. To fulfill this knowledge gap, we developed the first assessment of soil physicochemical (bulk density, penetration resistance, shear resistance, organic matter content) and biological (soil microarthropods biodiversity evaluated with the QBS‐ar index, that is, an index based on the idea that high‐quality soils have more groups of microarthropods that are morphologically better adapted to the soil than low‐quality soils) properties for this kind of logging operation. In three case study areas in Central Italy, we applied an experimental design to evaluate separately the impacts related to the passage of the machine and that of the silvicultural treatment itself. We further applied linear mixed‐effect models to investigate the relationship between changes in soil physicochemical and biological properties. We found the effect of the silvicultural treatment to be negligible, but there was a significant alteration of the investigated parameters in the soil affected by the passage of the machine. Soil penetration and shear resistance doubled in the forwarding trails (0.25 MPa and 4.02 t m−2, respectively) in comparison with the other two experimental treatments (control area and soil not affected by the machine passage; about 0.12 MPa and 2.10 t m−2, respectively). Soil organic matter and soil microarthropod biodiversity (QBS‐ar index) were reduced by 25% in the forwarding trails (about 30% and 92 respectively) in comparison with the soil not affected by the machine passage (about 39% and about 130, respectively). Such significant disturbance, which occurred even if the applied machinery had lower weight in comparison to other alternatives (forwarders), is related to the high number of machine passes needed to extract the woody material with forwarding bins applying the short wood system. We found a significant relationship between soil compaction and soil organic matter removal and microarthropod biodiversity, with the latter which resulted significantly lower in more compacted and organic matter‐poor soils. We demonstrated that this small‐scale extraction system can have a negative effect on soil features in the short term. We therefore recommend the application of best management practices, for instance placing brush mats and logging residues, on the forwarding trails to limit the soil disturbance within the framework of small‐scale forestry. We further recommend a wider application of aerial harvesting systems, which generally have lower impacts to the soil. However, this could happen only after an extensive training program aimed to increase the knowledge and skills of local loggers about aerial harvesting systems.

Improved greywater quality after biofiltration with a fibre-biofilter derived from plantain pseudo stem

In this study, we addressed the prevalent issue of untreated greywater discharge into waterbodies in many developing countries, despite the associated public health risks. Our approach involved utilizing fibers extracted from plantain pseudo-stems to enhance the quality of greywater through simple biofiltration setups. Greywater sourced from the GETFund Hostel of the University of Energy and Natural Resources in Sunyani, Ghana, served as the focal point of our investigation. Through the application of this biofilter, we achieved notable reductions in two crucial parameters for assessing greywater quality: biochemical oxygen demand (BOD) and chemical oxygen demand (COD), averaging at 30.4 % and 28.67 %, respectively. Furthermore, we conducted comparative analyses between the efficacy of plantain pseudo-stem fibers and carbonized coconut shell adsorbent, both individually and in composite form as biosorbents. While certain combinations of biofilters led to slight increases in conductivity, pH, and total dissolved solids (TDS) in the treated greywater, these variations were anticipated and attributed to potential organic matter leaching during the biofiltration process. Employing Fourier-transform infrared (FT-IR) spectroscopy, we detected significant spectral changes indicative of successful organic matter removal from the greywater. Specifically, we observed an intensified phenolic hydroxyl (OH) peak at 3300 cm⁻¹, which shifted marginally to 3335 cm⁻¹ post-biofiltration. Additionally, the emergence of a carboxylic hydroxyl stretch at 2850 cm⁻¹ post-biofiltration provided strong evidence supporting the efficacy of our approach in mitigating organic contaminants in greywater.

Pollution Status and Research Progress of Azole Fungicides in Environment

Because of its broad spectrum, low toxicity and high efficiency, azole fungicides are widely used in various types of agricultural production, personal care products, medicines and material surface protection, which inevitably makes them enter various environmental media through surface runoff, rainfall, atmospheric volatilization and farmland irrigation, posing potential threats to the surrounding environment and human health. In rural areas, fungicides sprayed on crops are usually difficult to play a full role, most of which tend to enter the surface by wet sedimentation and other ways, and then directly into the environment through surface runoff. It is well known that China has been a big agricultural producer since ancient times, and the annual application amount of pesticides is as high as 500,000-600,000 tons, ranking first in the world. As an important part of pesticide products, the annual sales of fungicides account for about 25% of the total sales of pesticides, which makes a large number of fungicides into the environment, causing pollution to the surrounding environment. In urban areas, the population density is large, and the large use of all kinds of personal care products makes a considerable part of fungicides enter the municipal pipe network with domestic sewage. At the same time, the fungicides used to protect the urban vegetation landscape will also flow into the municipal pipe network with rainfall and eventually enter the sewage treatment plant. At present, most of the sewage treatment process design, whether domestic or foreign, considers the removal of conventional organic matter, and the removal rate of trace organic matter such as fungicides is often very low, which makes the residual fungicides in sewage eventually return to the environment.

Investigating the use of CaCO3 particles synthesized in the Ca(OH)2-CO2-H2O system for organic matter removal: adsorption efficiency and recyclability

ABSTRACT In this study, we experimentally investigate the production and characterization of CaCO3 particles through the carbonation process of Ca(OH)2 and evaluate their potential application in removing organic matter. The CaCO3 particles were characterized using BET, SEM-EDX, FT-IR, particle size, and XRD techniques. Adsorption of organic matter was studied using synthetic solutions and samples from two surface water sources. Experiments were conducted at room temperature with adsorbent dosages ranging from 1.3 to 21.5 g/L, initial dissolved organic carbon concentrations between 2.5 and 20 mg/L (initial loading: 0.1–14.6 mgDOC/gCaCO3), and a contact time of at least 5 minutes. We observed a removal efficiency of 70–80% for DOC and 90–95% for UV254 at a low concentration of organic matter (humic acids, 2.5 mgDOC/L). At a concentration of 5.0 mg DOC/L, we achieved (i) 70–90% DOC removal for humic acid, (ii) 50–65% DOC removal for one surface water sample with SUVA254 of 2.4 L/mg·m, and (iii) 20–35% DOC removal for another surface water sample with SUVA254 of 4.3 L/mg·m. Furthermore, we investigated the performance of the prepared particles in repeated usage for organics removal. In conclusion, our findings propose areas for future research including optimizing particle cycling within the reaction environment, exploring particle utilization in reactors such as an up-flow particle bed, and assessing potential applications in a membrane contactor. The environmentally friendly and non-toxic nature of CaCO3 particles emphasizes their significance in future research and applications.

Effective and mechanistic insights into shale gas wastewater reverse osmosis concentrate treatment using ozonation-biological activated carbon process

Reverse osmosis (RO) plays a pivotal role in shale gas wastewater resource utilization. However, managing the reverse osmosis concentrate (ROC) characterized by high salinity and increased concentrations of organic matter is challenging. In this study, we aimed to elucidate the enhancement effects and mechanisms of pre-ozonation on organic matter removal efficacy in ROC using a biological activated carbon (BAC) system. Our findings revealed that during the stable operation phase, the ozonation (O3 and O3/granular activated carbon)-BAC system removes 43.6–72.2 % of dissolved organic carbon, achieving a 4–7 fold increase in efficiency compared with that in the BAC system alone. Through dynamic analysis of influent and effluent water quality, biofilm performance, and microbial community structure, succession, and function prediction, we elucidated the following primary enhancement mechanisms: 1) pre-ozonation significantly enhances the biodegradability of ROC by 4.5–6 times and diminishes the organic load on the BAC system; 2) pre-ozonation facilitates the selective enrichment of microbes capable of degrading organic compounds in the BAC system, thereby enhancing the biodegradation capacity and stability of the microbial community; and 3) pre-ozonation accelerates the regeneration rate of the granular activated carbon adsorption sites. Collectively, our findings provide valuable insights into treating ROC through pre-oxidation combined with biotreatment.

Application of red mud in hydrothermal remediation of Cd- and petroleum-contaminated soil

Developing a technique to simultaneously remove the harmful effects of organic matter and heavy metals from composite-polluted soil is of great importance, as it could reduce the time required for land restoration. In this study, red mud was used as an additive to remediate Cd- and petroleum-contaminated soil (CPCS) using hydrothermal technology, and its effects on the total organic carbon (TOC), total Cd, and available Cd (CdA) in the soil were evaluated. During hydrothermal extractions, when the temperature increased from 150 °C to 350 °C, the TOC removal efficiency increased from 16.32 % to 61.29 %, while the ratio of CdA (RCdA) decreased from 32.28 % to 10.72 %, and after adding 2 g of red mud, the RCdA decreased from 46.54 % to 20.30 %. During hydrothermal oxidations, adding red mud increased the TOC removal efficiency from 78.44 % at 0 g to 84.62 % at 3 g when the amount of oxidant was 30 mL, and RCdA decreased from 31.62 % to 19.46 %. These results indicate that hydrothermal treatments could significantly affect the organic substances in soil, and red mud played the roles of a catalyst and passivator during hydrothermal oxidation. The passivation of Cd by red mud was promoted under high-temperature conditions and an appropriate increase in the oxidant concentration and reaction time could promote the removal of organic matter and the reduction of CdA. However, excessive oxidants and reaction time could cause further decomposition of organic matter, leading to a decreased ability to capture Cd.

Facile and economic preparation of graphene hydrothermal nanocomposite from sunflower waste: Kinetics, isotherms and thermodynamics for Cd(II) and Pb(II) removal from water

Keeping the need for good water quality and the demand of climatic issues, the sunflower waste was converted into graphene hydrothermal nanocomposite absorbents for the removal of toxic Cd(II) and Pb(II) metal ions from water. The graphene composite materials were studied by scanning (SEM) and transmission electron microscopy (TEM), XRD analysis, TG and DSC, Raman and IR spectroscopy. According to SEM and TEM analysis, the decarbonized materials had a disordered structure with amorphous carbon with a small pore content. During the carbonization process, the pores space was opened due to the removal of amorphous organic matter and the formation of defects; providing a significant number of meso- and micropores. The prepared graphene composite showed 133.33 and 222.22 mg/g Langmuir adsorption of Cd(II) and Pb(II) at pH 6.0, dose 0.33 g/30 mL, initial concentration 300 mg/L, time 30 min and at 45 °C temperature using hydrothermal nanocomposite HTC/graphene oxide absorbent. The obtained results followed the sorption of heavy metal ions in a mixed-diffusion mode with the contribution of a second-order reaction between the active center of the sorbent and the metal ions. The Temkin and Dubinin-Radushkevich model’s parameters and thermodynamic results confirmed endothermic physical interactions among adsorbent and metal ions. This paper is highly useful for managing sunflower waste and purifying water; leading to the present demand for clean water and climatic issues. The production of the effective low-cost nanocomposite using green synthesis technologies (hydrothermal carbonization of raw materials) is highly useful for the removal of Cd(II) and Pb(II) toxic metal ions from water.

The Use of Microfiltration for the Pretreatment of Backwash Water from Sand Filters.

Tests of microfiltration efficiency used for the pretreatment of backwash water from sand filters were conducted at two water treatment plants treating surface water and infiltration water. Microfiltration efficiency was evaluated for three membrane modules: two with polymeric membranes and one with a ceramic membrane. This study showed that the contaminants that limit the reuse of backwash water from both plants by returning them to the water treatment line are mostly microorganisms, including pathogenic species (Clostridium perfringens). Additionally, in the case of backwash water from infiltration water treatment, iron and manganese compounds also had to be removed before its recirculation to the water treatment system. Unexpectedly, organic carbon concentrations in both types of backwash water were similar to those present in intake waters. Microfiltration provided for the removal of organic matter, ranging from 19.9% to 44.5% and from 7.2% to 53.9% for backwash water from the treatments of surface water and infiltration water, respectively. Furthermore, the efficiency of the iron removal from backwash water from infiltration water treatment was sufficient to ensure good intake water quality. On the other hand, manganese concentrations in the backwash water, from infiltration water treatment, pretreated using the microfiltration process exceeded the levels found in the intake water and were, therefore, an additional limiting factor for the reuse of the backwash water. In both types of backwash water, the number of microorganisms, including Clostridium perfringens (a pathogenic one), was a limiting parameter for backwash water reuse without pretreatment. The results of the present study showed the possibility for using microfiltration for the pretreatment of backwash water, regardless of its origin but not as the sole process. More complex technological systems are needed before recirculating backwash water into the water treatment system. The polyvinylidene fluoride (PVDF) membrane proved to be the most effective for DOC and microorganism removal from backwash water.

Enhancing gravity-driven membrane system performance in shale gas wastewater treatment: Effect and mechanism of sodium acetate solution backwashing

The low-carbon gravity-driven membrane (GDM) filtration technology has great potential for treating highly decentralized shale gas wastewater (SGW), but its performance requires further enhancement. This study explores the effects and underlying mechanisms of sodium acetate (NaAc) solution backwashing on enhancing GDM system performance in SGW treatment. Results indicated that NaAc solution backwashing for 30 min per day significantly improved the stable flux, organic matter removal rate, and total organic nitrogen removal rate by 64%, 176%, and 1085%, respectively. Structural and compositional analysis of the biofouling layer revealed that NaAc solution backwashing effectively reduced its thickness and coverage, thereby diminishing filtration resistance and enhancing stable flux. Furthermore, comparative analysis with pure water backwashing and evaluations of microbial community structures demonstrated that NaAc solution, as a carbon source, substantially stimulated microbial activity and growth, and optimized the microbial community within the biofouling layer. Specifically, NaAc solution backwashing selectively enriched functional microbes with denitrification and organic degradation abilities, such as Roseovarius, Marinobacter, Bacillus, and Citreitalea, thereby augmenting the GDM system’s nitrogen and carbon removal capabilities. Overall, the performance improvements observed were primarily attributed to the physical cleaning effects and bioaugmentation function provided by NaAc solution. This study offered valuable insights for designing and optimizing backwashing strategies in the GDM system.

Nickel augmented biochar for sustaining produced water treatment to decarbonize oil and gas industrial waste using anaerobic-aerobic granular cylindrical periodic discontinuous batch reactors

This study assessed the efficacy of granular cylindrical periodic discontinuous batch reactors (GC-PDBRs) for produced water (PW) treatment by employing eggshell and waste activated sludge (WAS) derived Nickel (Ni) augmented biochar. The synthesized biochar was magnetized to further enhance its contribution towards achieving carbon neutrality due to carbon negative nature, Carbon dioxide (CO2) sorption, and negative priming effects. The GC-PDBR1 and GC-PDBR2 process variables were optimized by the application of central composite design (CCD). This is to maximize the decarbonization rate. Results showed that the systems could reduce total phosphorus (TP) and chemical oxygen demand (COD) by 76–80% and 92–99%, respectively. Optimal organic matter and nutrient removals were achieved at 80% volumetric exchange ratio (VER), 5 min settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration with desirability values of 0.811 and 0.954 for GC-PDBR1 and GC-PDBR2, respectively. Employing four distinct models, the biokinetic coefficients of the GC-PDBRs treating PW were calculated. The findings indicated that First order (0.0758–0.5365) and Monod models (0.8652–0.9925) have relatively low R2 values. However, the Grau Second-order model and Modified Stover-Kincannon model have high R2 values. This shows that, the Grau Second Order and Modified Stover-Kincannon models under various VER, settling time, and MLSS circumstances, are more suited to explain the removal of pollutants in the GC-PDBRs. Microbiological evaluation demonstrated that a high VER caused notable rises in the quantity of several microorganisms. Under high biological selective pressure, GC-PDBR2 demonstrated a greater percentage of nitrogen removal via autotrophic denitrification and a greater number of nitrifying bacteria. The overgrowth of bacteria such as Actinobacteriota spp. Bacteroidota spp, Gammaproteobacteria, Desulfuromonas Mesotoga in the phylum, class, and genus, has positively impacted on granule formation and stability. Taken together, our study through the introduction of intermittent aeration GC-PDBR systems with added magnetized waste derived biochar, is an innovative approach for simultaneous aerobic sludge granulation and PW treatment, thereby providing valuable contributions in the journey toward achieving decarbonization, carbon neutrality and sustainable development goals (SDGs).

From laboratory to pilot-scale: Assessing dissolved organic matter, biological stability and per- and polyfluoroalkyl substances removal on managed aquifer recharge performance

Managed aquifer recharge (MAR) is a promising technique for enhancing groundwater resources and addressing water scarcity. Particularly, this research highlights the novelty and urgent need for MAR facilities in the Chungcheongnam-do region of South Korea as a solution to augment groundwater resources and combat water scarcity. This research encompasses a comprehensive assessment, ranging from laboratory-scale column experiments to pilot-scale tests, focusing on dissolved organic matter (DOM) characterization, natural organic matter (NOM) removal, and water quality improvement, including biological stability. In the laboratory, DOM characteristics of source water and recharged groundwater were analyzed using advanced dissolved organic characteristic tools, and their potential impacts on water quality, as well as per- and polyfluoroalkyl substances (PFASs) were assessed. DOM, total cell counts, and several PFASs with molecular weights >450 Da (particularly long-chain PFASs showing >99.9 % reduction) were effectively reduced in a laboratory-scale experiment. A laboratory-scale column study revealed that most selected PFASs were not effectively removed. Moving to the pilot-scale, a series of experiments were conducted to assess NOM removal during soil passage. Similar to the results of the laboratory-scale experiment, MAR demonstrated significant potential for reducing NOM concentrations, thus improving water quality. Regarding biological stability, assimilable organic carbon in production well (i.e., final produced water by MAR process) was lower than both two sources of surface water (e.g., SW1 and SW2). This suggests that water derived from PW (i.e., production well) exhibited biological stability, undergoing effective biodegradation by aerobic bacteria during soil passage. The findings from this study highlight the critical importance of implementing MAR techniques in regions facing water scarcity, emphasizing its potential to significantly enhance future water security initiatives.

Partial nitrification and simultaneous denitrification in sequential anaerobic and aerobic reactors: performance and microbial community dynamics

ABSTRACT The removal of organic matter and nitrogen from domestic sewage was evaluated using a system composed of two sequential reactors: an anaerobic reactor (ANR) with suspended sludge and an aerobic (AER) reactor with suspended and adhered sludge to polyurethane foams. Nitrogen removal consisted of AER operating at low dissolved oxygen (DO) concentrations; this favoured the simultaneous nitrification and denitrification (SND) process. The concentration of COD and N were 440 mgO2.L−1 and 37 mgTN.L−1, respectively. The operation was divided into three phases (P), lasting 51, 53, and 46 days, respectively. The initial DO concentrations applied in the AER were: 3.0 (PI) and 1.5 mg.L−1 (PII and PIII). In PIII, the AER effluent was recirculated to the ANR at a ratio of 0.25. Kinetic assays were performed to determine the nitrification and denitrification rates of the biomasses (ANR and AER in PIII). Changes in the microbial community were evaluated throughout phases PI to PIII by massive sequencing. In PIII, the best results obtained for chemical oxygen demand (COD) and total nitrogen (TN-N) removal efficiencies, were close to 94% and 65%, respectively. Under these conditions, system effluent concentrations below 30 mg COD.L−1 and 15 mg TN-N.L−1 were verified. The nitritation and nitration rates were 10.5 and 6.5 mg N.g VSS−1.h−1, while the denitrification via nitrite and nitrate were 6.8 and 5.8 mg N.g VSS−1.h−1, respectively. A mixotrophic community was prevalent, with Rhodococcus, Nitrosomonas, Pseudomnas, and Porphyromonas being dominant or co-dominant in most of the samples, confirming the SND process in the AER sludge.

Effect of microalgae and bacteria inoculation on the startup of bioreactors for paper pulp wastewater and biofuel production

The use of microalgae and bacteria as a strategy for the startup of bioreactors for the treatment of industrial wastewater can be a sustainable and economically viable alternative. This technology model provides satisfactory results in the nitrification and denitrification process for nitrogen removal, organic matter removal, biomass growth, sedimentation, and byproducts recovery for added-value product production. The objective of this work was to evaluate the performance of microalgae and bacteria in their symbiotic process when used in the treatment of paper pulp industry wastewater. The experiment, lasting fourteen days, utilized four bioreactors with varying concentrations in mgVSS/L of microalgae to bacteria ratio (R1-100:100, R2-100:300, R3-100:500, R4-300:100) in the startup process. Regarding the sludge volumetric index (SVI), the results show that the R1 and R2 reactors developed SVI30/SVI10 biomass in the range of 85.57 ± 7.33% and 84.72 ± 8.19%, respectively. The lipid content in the biomass of reactors R1, R2, R3 e R4 was 13%, 7%, 19%, and 22%, respectively. This high oil content at the end of the batch, may be related to the nutritional stress that the species underwent during this feeding regime. In terms of chlorophyll, the bioreactor with an initial inoculation of 100:100 showed better symbiotic growth of microalgae and bacteria, allowing exponential growth of microalgae. The total chlorophyll value for this bioreactor was 801.46 ± 196.96 μg/L. Biological removal of nitrogen from wastewater from the paper pulp industry is a challenge due to the characteristics of the effluent, but the four reactors operated in a single batch obtained good nitrogen removal. Ammonia nitrogen removal performances were 91.55 ± 9.99%, 72.13 ± 19.18%, 64.04 ± 21.34%, and 86.15 ± 30.10% in R1, R2, R3, and R4, respectively.

Aerobic composting characteristics of corn straw and pig manure under dynamic aeration

ABSTRACT The conventional aeration method is compulsorily continuous ventilation or aeration at equal intervals, and a uniform aeration rate does not vary during composting. A dynamic on-demand aeration approach based on the diverse oxygen consumption of microorganisms at different composting stages could solve the problems of insufficient oxygen supply or excessive aeration. This study aims to design an aerobic composting system with dynamic aeration, investigate the effects of dynamic aeration on the temperature rise and physicochemical characteristics during the aerobic composting of corn straw and pig manure, and optimise the control parameters of oxygen concentration. Higher temperatures and longer high-temperature durations were achieved under dynamic aeration, thereby accelerating the decomposition of organic compounds. Dynamic aeration effectively reduced the aeration frequency, the convective latent heat and moisture losses, and the power consumption in the middle and later stages of composting. The dynamic aeration regulated according to the oxygen concentration of 14%–17% in the exhaust was optimum. Under the optimal conditions, the period above 50 ℃ lasted 8.5 days, and the highest temperature, organic matter removal, and seed germination index reached 65.82 ℃, 37.59%, and 74.59%, respectively. The power consumption was decreased by 33.58% compared to the traditional intermittent aeration. Dynamic aeration would be a competitive approach for improving aerobic composting characteristics and reducing the power consumption and the hot exhaust gas emissions, especially in the cooling maturation stage, which was of great significance for realising the low-cost production of composting at scale and promoting the blossom of the organic fertiliser industry.