Mechanisms for simultaneous ozonation of sulfamethoxazole and natural organic matters in secondary effluent from sewage treatment plant

• SMX was mainly degraded by hydrolysis, isoxazole oxidation and double-bond addition. • Isoxazole oxidation and bond addition products were formed by direct ozonation. • Hydroxylated products were produced by indirect oxidation. • NOM mainly affected the degradation of SMX by consuming ^•OH rather than O₃. • Inhibitory effect of NOM on SMX removal was related to the components’ aromaticity. Sulfamethoxazole (SMX) is commonly detected in wastewater and cannot be completely decomposed during conventional treatment processes. Ozone (O₃) is often used in water treatment. This study explored the influence of natural organic matters (NOM) in secondary effluent of a sewage treatment plant on the ozonation pathways of SMX. The changes in NOM components during ozonation were also analyzed. SMX was primarily degraded by hydrolysis, isoxazole-ring opening, and double-bond addition, whereas hydroxylation was not the principal route given the low maximum abundances of the hydroxylated products, with m/z of 269 and 287. The hydroxylation process occurred mainly through indirect oxidation because the maximum abundances of the products reduced by about 70% after the radical quencher was added, whereas isoxazole-ring opening and double-bond addition processes mainly depended on direct oxidation, which was unaffected by the quencher. NOM mainly affected the degradation of micropollutants by consuming ^•OH rather than O₃ molecules, resulting in the 63%–85% decrease in indirect oxidation products. The NOM in the effluent were also degraded simultaneously during ozonation, and the components with larger aromaticity were more likely degraded through direct oxidation. The dependences of the three main components of NOM in the effluent on indirect oxidation followed the sequence: humic-like substances>fluvic-like substances>protein-like substances. This study reveals the ozonation mechanism of SMX in secondary effluent and provides a theoretical basis for the control of SMX and its degradation products in actual water treatment.     

Mesophilic and thermophilic anaerobic digestion of swine manure with sulfamethoxazole and norfloxacin: Dynamics of microbial communities and evolution of resistance genes

• SMX addition had negative effect on acetoclastic methanogens in mesophilic AD. • Thermophilic AD was more effective in eliminating resistance genes than mesophilic. • ARGs variations in AD were mainly affected by succession of microbial community. • Methane production was significant associated to ARGs reduction. The role of norfloxacin (NOR) and sulfamethoxazole (SMX) in mesophilic and thermophilic anaerobic digestion (AD) of pig manure, with respect to methane production and variations in the microbial community and resistance genes, including antibiotic resistance genes (ARGs), class I integrase (intI1), and heavy metal resistance genes (MRGs), was investigated. The results indicated that NOR exerted little influence on the microbial community, whereas SMX negatively affected the acetoclastic methanogens. The abundance of two sulfonamide resistance genes (sul1 and sul2), three quinolone resistance genes (qnrS, parC, and aac(6’)-Ib-cr), and intI1 decreased by 2‒3 orders of magnitude at the end of thermophilic AD. In contrast, mesophilic AD was generally ineffective in reducing the abundance of resistance genes. According to the results of redundancy analysis, the abundance of ARGs was affected primarily by microbial community dynamics (68.5%), rather than the selective pressure due to antibiotic addition (13.3%). Horizontal gene transfer (HGT) through intI1 contributed to 26.4% of the ARG variation. The archaeal community also influenced the changes in the resistance genes, and ARG reduction was significantly correlated with enhanced methane production. Thermophilic AD presented a higher methane production potential and greater reduction in resistance gene abundance.     

In situ formation of bimetallic FeNi nanoparticles on sand through green technology: Application for tetracycline removal

• In situ preparation of FeNi nanoparticles on the sand via green synthesis approach. • Removal of tetracycline using GS-FeNi in batch and column study. • Both reductive degradation and sorption played crucial role the process. • Reusability of GS-FeNi showed about 77.39±4.3% removal on 4th cycle. • TC by-products after interaction showed less toxic as compared with TC. In this study, FeNi nanoparticles were green synthesized using Punica granatum (pomegranate) peel extract, and these nanoparticles were also formed in situ over quartz sand (GS-FeNi) for removal of tetracycline (TC). Under the optimized operating conditions, (GS-FeNi concentration: 1.5% w/v; concentration of TC: 20 mg/L; interaction period: 180 min), 99±0.2% TC removal was achieved in the batch reactor. The removal capacity was 181±1 mg/g. A detailed characterization of the sorbent and the solution before and after the interaction revealed that the removal mechanism(s) involved both the sorption and degradation of TC. The reusability of reactant was assessed for four cycles of operation, and 77±4% of TC removal was obtained in the cycle. To judge the environmental sustainability of the process, residual toxicity assay of the interacted TC solution was performed with indicator bacteria (Bacillus and Pseudomonas) and algae (Chlorella sp.), which confirmed a substantial decrease in the toxicity. The continuous column studies were undertaken in the packed bed reactors using GS-FeNi. Employing the optimized conditions, quite high removal efficiency (978±5 mg/g) was obtained in the columns. The application of GS-FeNi for antibiotic removal was further evaluated in lake water, tap water, and ground water spiked with TC, and the removal capacity achieved was found to be 781±5, 712±5, and 687±3 mg/g, respectively. This work can pave the way for treatment of antibiotics and other pollutants in the reactors using novel green composites prepared from fruit wastes.     

Taxonomic and functional variations in the microbial community during the upgrade process of a full-scale landfill leachate treatment plant – from conventional to partial nitrification-denitrification

• Upgrade process was investigated in a full-scale landfill leachate treatment plant. • The optimization of DO can technically achieve the shift from CND to PND process. • Nitrosomonas was mainly responsible for ammonium oxidation in PND system. • An obviously enrichment of Thauera was found in the PND process. • Enhanced metabolic potentials on organics was found during the process update. Because of the low access to biodegradable organic substances used for denitrification, the partial nitrification-denitrification process has been considered as a low-cost, sustainable alternative for landfill leachate treatment. In this study, the process upgrade from conventional to partial nitrification-denitrification was comprehensively investigated in a full-scale landfill leachate treatment plant (LLTP). The partial nitrification-denitrification system was successfully achieved through the optimizing dissolved oxygen and the external carbon source, with effluent nitrogen concentrations lower than 150 mg/L. Moreover, the upgrading process facilitated the enrichment of Nitrosomonas (abundance increased from 0.4% to 3.3%), which was also evidenced by increased abundance of amoA/B/C genes carried by Nitrosomonas. Although Nitrospira (accounting for 0.1%–0.6%) was found to stably exist in the reactor tank, considerable nitrite accumulation occurred in the reactor (reaching 98.8 mg/L), indicating high-efficiency of the partial nitrification process. Moreover, the abundance of Thauera, the dominant denitrifying bacteria responsible for nitrite reduction, gradually increased from 0.60% to 5.52% during the upgrade process. This process caused great changes in the microbial community, inducing continuous succession of heterotrophic bacteria accompanied by enhanced metabolic potentials toward organic substances. The results obtained in this study advanced our understanding of the operation of a partial nitrification-denitrification system and provided a technical case for the upgrade of currently existing full-scale LLTPs.     

Removal,distribution and plant uptake of perfluorooctane sulfonate (PFOS) in a simulated constructed wetland system

• PFOS was removed by soil adsorption and plant uptake in the VFCW. • Uptake of PFOS by E. crassipes was more than that of C. alternifolius. • PFOS in wastewater can inhibit the removal of nutrients. • Dosing with PFOS changed the soil microbial community in the VFCW. A vertical-flow constructed wetland (VFCW) was used to treat simulated domestic sewage containing perfluorooctane sulfonate (PFOS). The removal rate of PFOS in the domestic sewage was 93%–98%, through soil adsorption and plant uptake, suggesting that VFCWs can remove PFOS efficiently from wastewater. The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake; moreover, the percentage of soil adsorption was 61%–89%, and was higher than that of the plants uptake (5%–31%). The absorption capacity of Eichhornia crassipes (E. crassipes) (1186.71 mg/kg) was higher than that of Cyperus alternifolius (C. alternifolius) (162.77 mg/kg) under 10 mg/L PFOS, and the transfer factor of PFOS in E. crassipes and C. alternifolius was 0.04 and 0.58, respectively, indicating that PFOS is not easily translocated to leaves from roots of wetland plants; moreover, uptake of PFOS by E. crassipes was more than that of C. alternifolius because the biomass of E. crassipes was more than that of C. alternifolius and the roots of E. crassipes can take up PFOS directly from wastewater while C. alternifolius needs to do so via its roots in the soil. The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen, total phosphorus, chemical oxygen demand, and ammonia nitrogen in the VFCW, which decreased by 15%, 10%, 10% and 12%, respectively. Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.     

Reutilize tire in microbial fuel cell for enhancing the nitrogen removal of the anammox process coupled with iron-carbon micro-electrolysis

• MFC promoted the nitrogen removal of anammox with Fe-C micro-electrolysis. • Reutilize pyrolysis waste tire as micro-electrolysis and electrode materials. • Total nitrogen removal efficiency of modified MFC increased to 85.00%. • Candidatus kuenenia and SM1A02 were major genera responsible for nitrogen removal. In this study, microbial fuel cells (MFCs) were explored to promote the nitrogen removal performance of combined anaerobic ammonium oxidation (anammox) and Fe-C micro-electrolysis (CAE) systems. The average total nitrogen (TN) removal efficiency of the modified MFC system was 85.00%, while that of the anammox system was 62.16%. Additionally, the effective operation time of this system increased from six (CAE system alone) to over 50 days, significantly promoting TN removal. The enhanced performance could be attributed to the electron transferred from the anode to the cathode, which aided in reducing nitrate/nitrite in denitrification. The H⁺ released through the proton exchange membrane caused a decrease in the pH, facilitating Fe corrosion. The pyrolyzed waste tire used as the cathode could immobilize microorganisms, enhance electron transport, and produce a natural Fe-C micro-electrolysis system. According to the microbial community analysis, Candidatus kuenenia was the major genus involved in the anammox process. Furthermore, the SM1A02 genus exhibited the highest abundance and was enriched the fastest, and could be a novel potential strain that aids the anammox process.     

A novel strategy for gas mitigation during swine manure odour treatment using seaweed and a microbial consortium

• Comprehensive mitigation of gas emissions from swine manure was investigated. • Additives addition for mitigation of gas from the manure has been developed. • Sargassum horneri, seaweed masking strategy controlled gas by 90%-100%. • Immediate reduction in emitted gas and improving air quality has been determined. • Microbial consortium with seaweed completely controlled gas emissions by 100%. Gas emissions from swine farms have an impact on air quality in the Republic of Korea. Swine manure stored in deep pits for a long time is a major source of harmful gas emissions. Therefore, we evaluated the mitigation of emissions of ammonia (NH₃), hydrogen sulfide (H₂S) and amine gases from swine manure with biological products such as seaweed (Sargassum horneri) and a microbial consortium (Bacillus subtilis (1.2 × 10⁹ CFU/mL), Thiobacillus sp. (1.0 × 10¹⁰ CFU/mL) and Saccharomyces cerevisiae (2.0 × 10⁹ CFU/mL)) used as additives due to their promising benefits for nutrient cycling. Overall, seaweed powder masking over two days provided notable control of over 98%-100% of the gas emissions. Furthermore, significant control of gas emissions was especially pronounced when seaweed powder masking along with a microbial consortium was applied, resulting in a gas reduction rate of 100% for NH₃, amines and H₂S over 10 days of treatment. The results also suggested that seaweed powder masking and a microbial consortium used in combination to reduce the gas emissions from swine manure reduced odour compared with that observed when the two additives were used alone. Without the consortium, seaweed decreased total volatile fatty acid (VFA) production. The proposed novel method of masking with a microbial consortium is promising for mitigating hazardous gases, simple, and environmentally beneficial. More research is warranted to determine the mechanisms underlying the seaweed and substrate interactions.     

Treating wastewater under zero waste principle using wetland mesocosms

• Smart wetland was designed to treat wastewater according to zero waste principle. • The system included a dynamic roughing filter, Cyperus papyrus (L.) and zeolite. • It removed 98.8 and 99.8% of chemical and bacterial pollutants in 3 days. • The effluent reused to irrigate a landscape and the sludge recycled as fertilizer. • The plant biomass is a profitable resource for antibacterial and antioxidants. The present investigation demonstrates the synergistic action of using a sedimentation unit together with Cyperus papyrus (L.) wetland enriched with zeolite mineral in one-year round experiment for treating wastewater. The system was designed to support a horizontal surface flow pattern and showed satisfactory removal efficiencies for both physicochemical and bacteriological contaminants within 3 days of residence time. The removal efficiencies ranged between 76.3% and 98.8% for total suspended solids, turbidity, iron, biological oxygen demand, and ammonia. The bacterial indicators (total and fecal coliforms, as well as fecal streptococci) and the potential pathogens (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) showed removal efficiencies ranged between 96.9% and 99.8%. We expect the system to offer a smart management for every component according to zero waste principle. The treated effluent was reused to irrigate the landscape of pilot area, and the excess sludge was recycled as fertilizer and soil conditioner. The zeolite mineral did not require regeneration for almost 36 weeks of operation, and enhanced the density of shoots (14.11%) and the height of shoots (15.88%). The harvested plant biomass could be a profitable resource for potent antibacterial and antioxidant bioactive compounds. This could certainly offset part of the operation and maintenance costs and optimize the system implementation feasibility. Although the experiment was designed under local conditions, its results could provide insights to upgrade and optimize the performance of other analogous large-scale constructed wetlands.     

Occurrence and fate of typical antibiotics in wastewater treatment plants in Harbin,North-east China

• The concentration distributions and removals of 12 antibiotics were investigated. • Macrolides and fluoroquinolones presented relatively higher concentrations. • The removal of antibiotics did not differ among the different treatment processes. As a new pollutant, antibiotics in the environment and their removal in wastewater treatment plants (WWTPs) have gained considerable attention. However, few studies investigated antibiotics in the north-eastern areas of China. By employing high-performance liquid chromatography-tandem mass spectrometry, the concentration distribution and removal of 12 antibiotics belonging to four types (cephalosporins, sulfonamides, fluoroquinolones, and macrolides) were investigated in influents and effluents as well as the removal efficiencies of four typical treatment processes in 18 wastewater treatment plants of Harbin City, north-eastern China. Macrolides and fluoroquinolones presented relatively higher detection concentrations and rates both in the water and in the sludge phases. Sulfonamides and cephalosporins displayed higher detection concentrations in the water phase. The representative antibiotics in influents and effluents included ROX, NOR, OFL, SMX, AZI, and CLA, with detection rates above 95%. The detection rates of the other six antibiotics exceeded 30%. In the sludge, the other five antibiotics, except SMX, presented relatively higher detection concentrations and rates, with detection rates greater than 95%. For cephalosporin, the detection rates of CTX and CFM in the sludge were 0. The removal efficiencies for the 12 antibiotics differed greatly, with average values ranging from 30% to 80% and the highest values for cephalosporin. The removal of antibiotics did not differ significantly among the four different treatment processes.     

Pollution and biodegradation of hexabromocyclododecanes: A review

• Bioremediation is the most cost-effective approach for degradation of HBCDs. • Bacteria or bacterial consortia are used in the cases of bio-augmentation. • Microbes combined with phytoremediation increase the remediation efficiency. Hexabromocyclododecanes (HBCDs) are the most common brominated flame-retardants after polybrominated diphenyl ethers. HBCDs can induce cancer by causing inappropriate antidiuretic hormone syndrome. Environmental contamination with HBCDs has been detected globally, with concentrations ranging from ng to mg. Methods to degrade HBCDs include physicochemical methods, bioremediation, and phytoremediation. The photodegradation of HBCDs using simulated sunlight or ultraviolet lamps, or chemical catalysts are inefficient and expensive, as is physicochemical degradation. Consequently, bioremediation is considered as the most cost-effective and clean approach. To date, five bacterial strains capable of degrading HBCDs have been isolated and identified: Pseudomonas sp. HB01, Bacillus sp. HBCD-sjtu, Achromobacter sp. HBCD-1, Achromobacter sp. HBCD-2, and Pseudomonas aeruginosa HS9. The molecular mechanisms of biodegradation of HBCDs are discussed in this review. New microbial resources should be explored to increase the resource library in order to identify more HBCD-degrading microbes and functional genes. Synthetic biology methods may be exploited to accelerate the biodegradation capability of existing bacteria, including modification of the degrading strains or functional enzymes, and artificial construction of the degradation microflora. The most potentially useful method is combining micro-degradation with physicochemical methods and phytoremediation. For example, exogenous microorganisms might be used to stimulate the adsorption capability of plants for HBCDs, or to utilize an interaction between exogenous microorganisms and rhizosphere microorganisms to form a new rhizosphere microbial community to enhance the biodegradation and absorption of HBCDs.     

The combined effects of biomass and temperature on maximum specific ammonia oxidation rate in domestic wastewater treatment

• Actual SAORs was determined using MLVSS and temperature. • Measured SAOR decreased with increasing MLVSS 1.1‒8.7 g/L. • Temperature coefficient (θ) decreased with increasing MLVSS. • Nitrification process was dynamically simulated based on laboratory-scale SBR tests. • A modified model was successfully validated in pilot-scale SBR systems. Measurement and predicted variations of ammonia oxidation rate (AOR) are critical for the optimization of biological nitrogen removal, however, it is difficult to predict accurate AOR based on current models. In this study, a modified model was developed to predict AOR based on laboratory-scale tests and verified through pilot-scale tests. In biological nitrogen removal reactors, the specific ammonia oxidation rate (SAOR) was affected by both mixed liquor volatile suspended solids (MLVSS) concentration and temperature. When MLVSS increased 1.6, 4.2, and 7.1-fold (1.3‒8.9 g/L, at 20°C), the measured SAOR decreased by 21%, 49%, and 56%, respectively. Thereby, the estimated SAOR was suggested to modify when MLVSS changed through a power equation fitting. In addition, temperature coefficient (θ) was modified based on MLVSS concentration. These results suggested that the prediction of variations ammonia oxidation rate in real wastewater treatment system could be more accurate when considering the effect of MLVSS variations on SAOR.     

Ammonia removal from low-strength municipal wastewater by powdered resin combined with simultaneous recovery as struvite

• Powdered resin was employed for ammonia recovery from municipal wastewater. • Powdered resin achievedefficient ammonia removal under various working conditions. • Co-existing cations indicated competitive adsorption of ammonia. • Ammonia was recoveredby two-stage crystallization coupled with ion exchange. Low-strength municipal wastewater is considered to be a recoverable nutrient resource with economic and environmental benefits. Thus, various technologies for nutrient removal and recovery have been developed. In this paper, powdered ion exchange resin was employed for ammonia removal and recovery from imitated low-strength municipal wastewater. The effects of various working conditions (powdered resin dosage, initial concentration, and pH value) were studied in batch experiments to investigate the feasibility of the approach and to achieve performance optimization. The maximum adsorption capacity determined by the Langmuir model was 44.39 mg/g, which is comparable to traditional ion exchange resin. Further, the effects of co-existing cations (Ca²⁺, Mg²⁺, K⁺) were studied. Based on the above experiments, recovery of ammonia as struvite was successfully achieved by a proposed two-stage crystallization process coupled with a powdered resin ion exchange process. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results revealed that struvite crystals were successfully gained in alkaline conditions (pH= 10). This research demonstrates that a powdered resin and two-stage crystallization process provide an innovative and promising means for highly efficient and easy recovery from low-strength municipal wastewater.     

Anaerobic biodegradation of trimethoprim with sulfate as an electron acceptor

Anaerobic biodegradation of trimethoprim (TMP) coupled with sulfate reduction. Demethylation of TMP is the first step in the acclimated microbial consortia. The potential degraders and fermenters were enriched in the acclimated consortia. Activated sludge and river sediment had similar core microbiomes. Trimethoprim (TMP) is an antibiotic frequently detected in various environments. Microorganisms are the main drivers of emerging antibiotic contaminant degradation in the environment. However, the feasibility and stability of the anaerobic biodegradation of TMP with sulfate as an electron acceptor remain poorly understood. Here, TMP-degrading microbial consortia were successfully enriched from municipal activated sludge (AS) and river sediment (RS) as the initial inoculums. The acclimated consortia were capable of transforming TMP through demethylation, and the hydroxyl-substituted demethylated product (4-desmethyl-TMP) was further degraded. The biodegradation of TMP followed a 3-parameter sigmoid kinetic model. The potential degraders (Acetobacterium, Desulfovibrio, Desulfobulbus, and unidentified Peptococcaceae) and fermenters (Lentimicrobium and Petrimonas) were significantly enriched in the acclimated consortia. The AS- and RS-acclimated TMP-degrading consortia had similar core microbiomes. The anaerobic biodegradation of TMP could be coupled with sulfate respiration, which gives new insights into the antibiotic fate in real environments and provides a new route for the bioremediation of antibiotic-contaminated environments.     

Enhanced enzymatic removal of anthracene by the mangrove soil-derived fungus, Aspergillus sydowii BPOI

• A. sydowii strain bpo1 exhibited 99.8% anthracene degradation efficiency. • Four unique metabolic products were obtained after anthracene degradation. • Ligninolytic enzymes induction played vital roles in the removal of anthracene. • Laccase played a crucial role in comparison with other enzymes induced. The present study investigated the efficiency of Aspergillus sydowii strain bpo1 (GenBank Accession Number: MK373021) in the removal of anthracene (100 mg/L). Optimal degradation efficiency (98.7%) was observed at neutral pH, temperature (30℃), biomass weight (2 g) and salinity (0.2% w/v) within 72 h. The enzyme analyses revealed 131%, 107%, and 89% induction in laccase, lignin peroxidase, and manganese peroxidase respectively during anthracene degradation. Furthermore, the degradation efficiency (99.8%) and enzyme induction were significantly enhanced with the addition of 100 mg/L of citric acid and glucose to the culture. At varying anthracene concentrations (100–500 mg/L), the degradation rate constants (k₁) peaked with increasing concentration of anthracene while the half-life (t_1/2) decreases with increase in anthracene concentration. Goodness of fit (R² = 0.976 and 0.982) was observed when the experimental data were subjected to Langmuir and Temkin models respectively which affirmed the monolayer and heterogeneous nature exhibited by A. sydwoii cells during degradation. Four distinct metabolites; anthracene-1,8,9 (2H,8aH,9aH)-trione, 2,4a-dihydronaphthalene-1,5-dione, 1,3,3a,7a-tetrahydro-2-benzofuran-4,7-dione and 2-hydroxybenzoic acid was obtained through Gas Chromatography-Mass spectrometry (GC-MS). A. sydowii exhibited promising potentials in the removal of PAHs.     

Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through short-cut nitrification-denitrification and partial anammox

• Sludge fermentation liquid addition resulted in a high NAR of 97.4%. • Extra NH₄⁺-N from SFL was removed by anammox in anoxic phase. • Nitrogen removal efficiency of 92.51% was achieved in municipal wastewater. • The novel system could efficiently treat low COD/N municipal wastewater. Biological nitrogen removal of wastewater with low COD/N ratio could be enhanced by the addition of wasted sludge fermentation liquid (SFL), but the performance is usually limited by the introducing ammonium. In this study, the process of using SFL was successfully improved by involving anammox process. Real municipal wastewater with a low C/N ratio of 2.8–3.4 was treated in a sequencing batch reactor (SBR). The SBR was operated under anaerobic-aerobic-anoxic (AOA) mode and excess SFL was added into the anoxic phase. Stable short-cut nitrification was achieved after 46d and then anammox sludge was inoculated. In the stable period, effluent total inorganic nitrogen (TIN) was less than 4.3 mg/L with removal efficiency of 92.3%. Further analysis suggests that anammox bacteria, mainly affiliated with Candidatus_Kuenenia, successfully reduced the external ammonia from the SFL and contributed approximately 28%–43% to TIN removal. Overall, this study suggests anammox could be combined with SFL addition, resulting in a stable enhanced nitrogen biological removal.     

Ammonia and phosphorus removal from agricultural runoff using cash crop waste-derived biochars

• Orange tree residuals biochar had a better ability to adsorb ammonia. • Modified tea tree residuals biochar had a stronger ability to remove phosphorus. • Partially-modified biochar could remove ammonia and phosphorus at the same time. • The real runoff experiment showed an ammonia nitrogen removal rate of about 80%. • The removal rate of total phosphorus in real runoff experiment was about 95%. Adsorption of biochars (BC) produced from cash crop residuals is an economical and practical technology for removing nutrients from agricultural runoff. In this study, BC made of orange tree trunks and tea tree twigs from the Laoguanhe Basin were produced and modified by aluminum chloride (Al-modified) and ferric sulfate solutions (Fe-modified) under various pyrolysis temperatures (200°C–600°C) and residence times (2–5 h). All produced and modified BC were further analyzed for their abilities to adsorb ammonia and phosphorus with initial concentrations of 10–40 mg/L and 4–12 mg/L, respectively. Fe-modified Tea Tree BC 2h/400°C showed the highest phosphorus adsorption capacity of 0.56 mg/g. Al-modified Orange Tree BC 3h/500°C showed the best performance for ammonia removal with an adsorption capacity of 1.72 mg/g. FTIR characterization showed that P = O bonds were formed after the adsorption of phosphorus by modified BC, N-H bonds were formed after ammonia adsorption. XPS analysis revealed that the key process of ammonia adsorption was the ion exchange between K⁺ and NH₄⁺. Phosphorus adsorption was related to oxidation and interaction between PO₄^3– and Fe³⁺. According to XRD results, ammonia was found in the form of potassium amide, while phosphorus was found in the form of iron hydrogen phosphates. The sorption isotherms showed that the Freundlich equation fits better for phosphorus adsorption, while the Langmuir equation fits better for ammonia adsorption. The simulated runoff infiltration experiment showed that 97.3% of ammonia was removed by Al-modified Orange tree BC 3h/500°C, and 92.9% of phosphorus was removed by Fe-modified Tea tree BC 2h/400°C.     

Acceleration of the particulate organic matter hydrolysis by start-up stage recovery and its original microbial mechanism

• Carbon availability was partially solved by POM recovery and fermentation. • 12% carbon sources were regenerated by fermentation of the entrapped 35% TCOD. • The unique microbial communities facilitated the efficient hydrolysis of the POM. • Considerable economic benefits in aeration power and ECS dosage were anticipated. To address the availability of carbon sources for denitrification, the accelerated hydrolysis of the most abundant but low-availability fraction of particulate organic matter (POM) was investigated. Mesh sieves with different pore sizes were used as primary pretreatment at the start-up-stage of the biological process to separate some POM from the liquid system. The changes in soluble carbohydrates and proteins were monitored to investigate the hydrolysis performance of the sieved POM, with waste activated sludge (WAS) as the control test. The results showed that an average of 35% POM could be entrapped before filtrate mat development. In addition, benefiting from the high polysaccharides concentration, as well as the high availability due to the relatively loose physical structure, a 23% hydrolysis efficiency of POM was obtained, in contrast to that of WAS (3.4%), with a hydrolysis constant of 0.39 h⁻¹. The prominent performance was also attributed to the unique microbial communities having been domesticated at a lower temperature, especially the cellulose-degrading bacteria Paraclostridium and psychrophile Psychrobacter, making up 6.94% and 2.56%, respectively. Furthermore, the potential benefits and application of improved POM hydrolysis by start-up stage recovery via mesh sieves combined with anaerobic fermentation were evaluated, including selective POM entrapment, alleviation of blockage and wear, and a reduction in aeration energy. By the proposed strategy, carbon availability for biological nutrient removal (BNR) processes is anticipated to be improved more economically than that can be achieved by primary clarifier elimination.     

Bioaerosolization behavior along sewage sludge biostabilization

• Aerosolization behavior during a lab-scale sludge biostabilization was determined. • Many pathogenic species were identified to be preferentially aerosolized. • Bioaerosol concentration along the biostabilization ranged from 160 to 1440 cell/m³. • Sludge aerosolization behavior was different with that of other biowaste. Biostabilization is a cost-effective method for the beneficial utilization of sewage sludge. However, during the operation of sludge biostabilization, some microbial species could be released into the atmospheric environment from the solid-phase of sludge easily and present a high risk to human health. This study aimed to evaluate the risk of bioaerosol during sludge biostabilization. We found a total of nine bacterial phyla, one archaeal phylum, and two fungal phyla in the bioaerosol samples. Among them, Proteobacteria, Actinobacteria, Bacteroidetes, and Ascomycota were the dominant phyla. In addition, the bioaerosolization indexes (BI) of prokaryotic phyla and fungal phyla ranged 0–45 and 0–487, respectively. Massilia, Pseudarthrobacter, Pseudomonas, Tremellales spp., and Fusarium were the preferentially aerosolized microbial genera with maximum bioaerosolization indexes of 19962, 10360, 1802, 3055, and 7398. The bioaerosol concentration during the biostabilization ranged from 160 to 1440 cell/m³, and we identified species such as Stenotrophomonas rhizophila and Fusarium graminerum with high bioaerosolization indexes that could be threats to human health. Euryachaeota, which belongs to archaeal phyla, had the highest biostabilization index in our study. We also found that Pseudarthrobacter was the easiest to aerosolize during the sludge biostabilization process.     

Surface water treatment benefits from the presence of algae: Influence of algae on the coagulation behavior of polytitanium chloride

• Emerging titanium coagulation was high-efficient for algae-laden water treatment. • Polytitanium coagulation was capable for both algae and organic matter removal. • Surface water purification was improved by around 30% due to algae inclusion. • Algae functioned as flocculant aid to assist polytitanium coagulation. • Algae could enhance charge neutralization capability of polytitanium coagulant. Titanium-based coagulation has proved to be effective for algae-laden micro-polluted water purification processes. However, the influence of algae inclusion in surface water treatment by titanium coagulation is barely reported. This study reports the influence of both Microcystis aeruginosa and Microcystis wesenbergii in surface water during polytitanium coagulation. Jar tests were performed to evaluate coagulation performance using both algae-free (controlled) and algae-laden water samples, and floc properties were studied using a laser diffraction particle size analyzer for online monitoring. Results show that polytitanium coagulation can be highly effective in algae separation, removing up to 98% from surface water. Additionally, the presence of algae enhanced organic matter removal by up to 30% compared to controlled water containing only organic matter. Polytitanium coagulation achieved significant removal of fluorescent organic materials and organic matter with a wide range of molecular weight distribution (693–4945 Da) even in the presence of algae species in surface water. The presence of algae cells and/or algal organic matter is likely to function as an additional coagulant or flocculation aid, assisting polytitanium coagulation through adsorption and bridging effects. Although the dominant coagulation mechanisms with polytitanium coagulant were influenced by the coagulant dosage and initial solution pH, algae species in surface water could enhance the charge neutralization capability of the polytitanium coagulant. Algae-rich flocs were also more prone to breakage with strength factors approximately 10% lower than those of algae-free flocs. Loose structure of the flocs will require careful handling of the flocs during coagulation-sedimentation-filtration processes.