Biological wastewater treatment is currently the most cost-effective and sustainable method, but it is necessary to supplement it with environmentally friendly physicochemical methods because of its inefficiency in the removal of some recalcitrant pollutants. Nano-sized palladium represents a promising catalyst for the remediation of multiple recalcitrant pollutants. Microorganisms can reduce ionic palladium to palladium nanoparticles under mild conditions and act as dispersants, stabilizers, and support materials for palladium catalysts, forming microbial-loaded biologenic palladium. Biologenic palladium combines the advantages of biological treatment and palladium catalysis, providing a novel solution to wastewater purification. Herein, this review was focused on the formation and the wastewater treatment performance of biologenic palladium. In this work, the formation mechanism of biologenic palladium is elucidated. The synergistic effect of microorganisms and palladium nanoparticles in removing pollutants is analyzed. The pollutants and wastewater treatment scenarios suitable for biologenic palladium treatment, as well as the purification efficiency, are summarized. This review also provides insights into the limitations faced by the large-scale application of biologenic palladium and future research directions that may assist in improving its efficiency and practical application.

This study assesses the improvement in nitrogen and phosphorus removal from wastewater achieved through the integration of zeolite and attapulgite carrier materials into the activated sludge (AS) process. It was found that the addition of these materials significantly enhanced the processing performance of the reactor. Specifically, the use of zeolite and attapulgite powders increased sludge particle sizes to averages of 231.56 mu m and 219.62 mu m, respectively. This facilitated micro-granule formation, substantially improving the settling characteristics of the sludge and boosting the activity and proliferation of essential microbes. Illumina MiSeq sequencing demonstrated significant accumulations of DGAOs (Candidatus_Competibacter) and DPAOs (Candidatus_Accumulibacter). Furthermore, these carriers augmented the protein content in extracellular polymers, enhancing the hydrophobicity of the sludge and promoting aggregation. Comparative analysis based on the extended Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory indicated a preferential adhesion affinity of sludge for zeolite compared to attapulgite, attributed primarily to Lewis acid-base and electric double-layer interactions. These findings underscore zeolite's enhanced efficacy in biomass fixation and suggest significant potential for the technological advancement of wastewater treatment plants.

Microbial reduction of perchlorate (ClO4-) is emerging as a cost-effective strategy for groundwater remediation. However, the effectiveness of perchlorate reduction can be suppressed by the common co-contamination of nitrate (NO3-). We propose a means to overcome the limitation of ClO4- reduction: depositing palladium nanoparticles (Pd0NPs) within the matrix of a hydrogenotrophic biofilm. Two H2-based membrane biofilm reactors (MBfRs) were operated in parallel in long-term continuous and batch modes: one system had only a biofilm (bio-MBfR), while the other incorporated biogenic Pd0NPs in the biofilm matrix (bioPd-MBfR). For long-term co-reduction, bioPd-MBfR had a distinct advantage of oxyanion reduction fluxes, and it particularly alleviated the competitive advantage of NO3- reduction over ClO4- reduction. Batch tests also demonstrated that bioPd-MBfR gave more rapid reduction rates for ClO4- and ClO3- compared to those of bio-MBfR. Both biofilm communities were dominated by bacteria known to be perchlorate and nitrate reducers. Functional-gene abundances reflecting the intracellular electron flow from H2 to NADH to the reductases were supplanted by extracellular electron flow with the addition of Pd0NPs.

The persistence of chlorinated phenols in the environment is a major concern due to their persistence and toxicity, yet advanced remediation methods are actually limited. For instance, reductive dechlorination of chlorophenols utilizing palladium nanoparticles (PdNPs) supported on hydrogen-transfer membranes is not fully efficient. Here we tested the simultaneous microbial-driven and Pd-catalyzed reduction of 2,4-dichlorophenol (2,4-DCP) for removal rate, selectivity of reduction products, and optimal reaction conditions. For that we compared three hydrogen-based membrane reactors: a 'Pd-biofilm reactor' with Pd nanoparticles and a biofilm, with two controls: a 'biofilm reactor' with biofilm alone, and a 'Pd-film reactor' with Pd nanoparticles alone. Results show that the Pd-biofilm reactor removed 89.3% of total phenols, versus 15.7% for the biofilm reactor and 19.5% for the Pd-film reactor. The strong adsorption capacity of Pd-biofilm enhanced dechlorination. This elevated local chlorophenols concentration led to a 2-4 times higher reduction rate within Pd-biofilm compared to abiotic Pd-film. The presence of nitrate enhances phenol removal over Pd-biofilm but inhibited 2,4-DCP dechlorination. Similarly, high concentrations of nitrite, above 250 mu M, inhibited 2,4-DCP reduction, predominantly in microbial processes rather than in catalytic reduction. Increasing hydrogen pressure facilitated the reduction of both 2,4-DCP and nitrate by Pd-biofilm, with an optimal pH of 7.0 for Pd-biofilm. The Pd-biofilm reactor decreased total phenols from 5-10 mg L-1 to the recommended threshold of 0.1 mg L-1 in 55 days, thus appearing as an efficient technique to clean chlorophenol-contaminated waters.

Non -conventional water recovery, recycling, and reuse have been considered imperative approaches to addressing water scarcity in China. The objective of this study was to evaluate the technical and economic feasibility of Water Reclamation Plants (WRP) based on an anaerobic-anoxic-oxic membrane bioreactor (A 2 O- MBR) system for unconventional water resource treatment and reuse in towns (domestic sewage and rainwater). Rainwater is collected and stored in the rainwater reservoir through the rainwater pipe network, and then transported to the WRP for treatment and reuse through the rainwater reuse pumping station during the peak water demand period. During a year of operation and evaluation process, a total of 610,000 cubic meters of rainwater were reused, accounting for 10.4 % of the treated wastewater. In the A 2 O-MBR operation, the average effluent concentrations for COD (chemical oxygen demand), NH 4 + -N (ammonium), TN (total nitrogen), and TP (total phosphorus) were 14.23 +/- 4.07 mg/L, 0.22 +/- 0.26 mg/L, 11.97 +/- 1.54 mg/L, and 0.13 +/- 0.09 mg/L, respectively. The effluent quality met standards suitable for reuse in industrial cooling water or for direct discharge. The WRP demonstrates a positive financial outlook, with total capital and operating costs totaling 0.16 $/m 3 . A comprehensive cost -benefit analysis indicates a positive net present value for the WRP, and the estimated annualized net profit is 0.024 $/m 3 . This research has achieved near -zero discharge of wastewater and effective allocation of rainwater resources across time and space.

4-Nitrophenol (4 -NP) poses significant threats to both ecosystems and human health, making it essential and highly beneficial to take effective measures to mitigate its impact. Herein, eggshell membrane (ESM) with mussel -inspired polydopamine coatings (ESM-PDA) was constructed and utilized as a template for the immobilization of Pd NPs, resulting in ESM-PDA-Pd formation. The catalyst ESM-PDA-Pd exhibits exceptional performance in reducing 4 -NP, and the TOF (turnover frequency) for ESM-PDA-Pd was determined to be 3.3 x 10 (-5) mmol center dot mg (- 1) center dot min (- 1) . Moreover, ESM-PDA-Pd demonstrates excellent catalytic activity in reducing other nitrophenols, including 2-nitrophenol (0.2196 min (- 1) ) and 2,4,6-nitrophenol (0.1177 min( - 1) ). Notably, the catalyst demonstrated brilliant recyclability, removing 92.4 % of 4 -NP within 20 min after undergoing five consecutive runs. This underscores its potential for sustained and effective use in multiple cycles of nitrophenol reduction reactions. Furthermore, the measured K (app) in various water samples is as follows: ultrapure water (0.135 min (- 1) ) > tap water (0.109 min (- 1) ) > river water (0.083 min (- 1) ), indicating its significant potential for industrial applications.

Anammox has been widely applied for treating high ammonia-nitrogen leachate, but challenges remain due to the phosphorus in the wastewater and by-products nitrate (NO3-). Therefore, we combined partial denitrificationanammox and hydroxyapatite crystallization within a single UASB reactor. This method achieved an effluent with a 4.27 +/- 0.45 mg TN/L and a maximum PO43- removal efficiency of 68.31 +/- 5.42 %. The addition of excess calcium led to an increase in phenylalanine-like substances, the humification index (HIX) of extracellular polymeric substances (EPS), and the MLVSS/MLSS ratio. These changes indicated that hydroxyapatite coated the initial granular sludge, causing it to crack and re-granulate, but the MLVSS didn't decrease significantly. Therefore, calcium addition didn't significantly impact the function of biomass. Metagenomic analysis revealed that by-products NO3- was removed through partial denitrification using in-situ refractory dissolved organic matters in SL. The formation of hydroxyapatite crystals is the main pathway for PO43- removal, and biological process also contributed to some PO43- removal. Overall, our study provided a viable solution for the simultaneous removal of nitrogen and recovery of phosphorus from high ammonia-nitrogen wastewater.

Single-atom catalysts (SACs) have been widely studied in Fenton-like reactions, wherein their catalytic performance could be further enhanced by adjusting electronic structure and regulating coordination environment, although relevant research is rarely reported. This text elucidates fabrication of dual atom catalyst systems aimed at augmenting their catalytic efficiency. Herein, atomically dispersed copper-zinc (Cu-Zn) dual sites anchored on nitrogen (N)-doped porous carbon (NC), referred to as CuZn-NC, were synthesized using cage-encapsulated pyrolysis and host-guest strategies. The CuZn-NC catalyst exhibited high activity in activation of peroxymonosulfate (PMS) for degradation of organic pollutants. Based on synergistic effects of adjacent Cu and Zn atom pairs, CuZn-NC (PMS) system achieved 94.44 % bisphenol A (BPA) degradation in 24 min. The radical pathway predominated, and coexistence of non-radical species was demonstrated for BPA degradation in CuZnNC/PMS system. More importantly, CuZn-NC/PMS system showed generality for degradation of various refractory contaminants. Our experiments indicate that CuZn-N sites on CuZn-NC act as active sites for bonding PMS molecules with optimal binding energy, while pyrrolic N sites are considered as adsorption sites for organic molecules. Overall, this research designs diatomic site catalysts (DACs), with promising implications for wastewater treatment.

A green and universal synthesis strategy was demonstrated for preparation of bimetallic Pd-Ag alloy nanoparticles supported on polydopamine-functionalized kaolin (kaolin-PDA-PdAg), where bimetallic PdAg alloy was synthesized by co-reduction of Na2PdCl4 and AgNO3 with sodium citrate. Characterization results, including TEM results and XPS results, confirmed that bimetallic Pd-Ag was alloying state and kaolin-PDA-PdAg was successfully synthesized through mussel-inspired chemistry. The kaolin-PDA-PdAg nanocomposite exhibited excellent catalytic activity and performance towards reduction of 4-nitrophenol, whose rate constant was found to be 3.46 min-1 under condition of high concentration (10 mM) of 4-nitrophenol. Besides, kaolin-PDA-PdAg nanocomposite showed high catalytic performance for methyl orange and safranine-T as well. The high catalytic activity of kaolin-PDA-PdAg could be elucidated by electronic effect and synergistic effect of bimetallic Pd-Ag alloy. These results suggest that kaolin-PDA-PdAg composites could be applied as high-efficiency catalysts for reduction of 4-nitrophenol and degradation of organic dyes. Furthermore, abundance and low-priced of raw materials kaolin, green and versatility of synthetic method endow kaolin-PDA-PdAg composites with broad application prospects. Strategy of bimetallic Pd-Ag alloy anchored on kaolin in this text could provide an efficient platform for synthesis of bimetallic alloy nanoparticles loaded on various materials.

Sb is classified as a priority pollutant, to control the pollution in aquatic environments of Sb, enhance the understanding of Sb biogeochemical cycle, the effects of sulfate and nitrate on antimonate (Sb(V)) removal in a Hydrogen-Based Membrane Biofilm Reactor (H-2-MBfR) were investigated. With the input of sulfate, the MBfR achieved 90% Sb removal and a removal flux up to 0.76 g Sb/m(2).day. The Sb(V) was reduced to Sb(III), which was primarily Sb2S3 solids retained in the biofilm. Furthermore, the mechanism of antimonate reduction shifted from enzymatic reduction with no sulfate input to abiotic reduction based on sulfide produced microbially being the reductant. The subsequent input of nitrate suppressed Sb(V) reduction and removal, along with suppressing sulfate reduction. Nitrate became the dominant electron acceptor, which led to Sb2S3 oxidation and the net release of Sb(V) and SO42-. This work reinforces that the H-2-MBfR is a promising bioremediation strategy for antimonate removal, and it provides mechanistic insights regarding the impacts of sulfate and nitrate on antimonate reduction and removal.

Sulfisoxazole (SIZ), a common antimicrobial prescribed for treating infections in livestock, is frequently detected in surface water and groundwater along with nitrate. The interactions of SIZ biotransformation and nitrate removal were investigated in a H2-based membrane biofilm reactor (H2-MBfR) through long-term reactor operation augmented by short-term batch experiments in serum bottles. Denitrification in the H2-MBfR was not influenced by SIZ when its input concentration was <= 5 mg L-1, although SIZ removal was inhibited by nitrate. Transformation products identified by mass spectrometry were formed via hydrogenation (reduction) reactions. The addition of SIZ shaped the microbial community structure, leading to the relative abundance of denitrifiers decreasing with the highest SIZ loading. Sulfate-reducing bacteria (SRB) were present in all stages, as the bio-films had relatively high abundances of the dsrA gene and its transcription products, while sulfide was generated in the final stage. SRB also appeared to be important in SIZ biotransformation, perhaps using SIZ as an electron donor, electron acceptor, or both. Concurrent SIZ removal and stable denitrification make the H2-MBfR a pro-spective technology for the treatment of wastewaters polluted with nitrate and SIZ.

Chlorinated nitroaromatic antibiotic chloramphenicol (CAP) is a persistent pollutant that is widely present in environments. A H2 transfer membrane biofilm reactor (H2-MBfR) and short-term batch tests were setup to investigate the co-removal of CAP and NO3-. Results showed that the presence of CAP (<10 mg L-1) has no effect on the denitrification process while 100% removal efficiency of CAP can be obtained when nitrate was absent. Nitroaromatic reduction and completely dechlorination were successfully realized when CAP was removed. The CAP transformation product p-aminobenzoic acid (PABA) was detected and batch tests revealed that the hydroxy carboxylation was far faster than nitroaromatic reduction when p-nitrobenzyl alcohol (PNBOH) was conversed to p-aminobenzoic acid (PABA). The path way of CAP degradation was proposed based on the intermediate's analysis. Microbial community analysis indicated that Pleomorphomonadaceae accounts for the dechlorination of CAP.

The simultaneous saccharification and fermentation (SSF) technique holds promise for the conversion of lignocellulose to ethanol. However, the optimal fermentation temperature of yeast is lower than the enzymatic hydrolysis temperature of the saccharification process, which leads to the temperature of the actual production process of SSF usually being lower than 38 °C. In this work, two ultraviolet (UV)-induced mutations were performed step by step using Saccharomyces cerevisiae BY4742 as the original strain to enable the yeast to perform well at higher temperatures. Thermotolerant strains obtained through mutagenesis and screening, YUV1-1 and YUV2-2, were utilized for fermentation and SSF at a targeted temperature of 40 °C. They obtained ethanol yields comparable to those at 38 °C in SSF, whereas the ethanol yields of the original strain at 40 °C decreased by about 10% compared to those at 38 °C. This study proves that thermotolerant strains adapted to elevated fermentation and SSF temperatures can be obtained through UV mutagenesis and screening, thereby increasing the stability of the fermentation and SSF processes and lowering the subsequent distillation costs.

Hydrogen-based membrane biofilm reactors (MBfRs) are effective for nitrogen removal. However, the safety of hydrogen limited the application of MBfR. Here, a hydrogen-based partial denitrification system coupled with anammox (H2-PDA) was constructed in an MBfR for reducing hydrogen demand significantly. The metabolomics and structures of microbial communities were analyzed to determine the phenotypic differences and drivers underlying denitrification, anammox, and H2-PDA. These findings indicated that total nitrogen (TN) removal increased from 57.1% in S1 to 93.7% in S2. During the H2-PDA process, partial denitrification and anammox contributed to TN removal by 93.7% and 6.3%, respectively. Community analysis indicated that the H2-PDA system was dominated by the genus Meiothermus, which is involved in partial denitrification. Collectively, these findings confirmed the feasibility of incorporating the H2-PDA process in a MBfR and form a foundation for the establishment of novel and practical methods for efficient nitrogen removal.

The use of hydrogen (H2)-based membrane biofilm reactor (MBfR) has proven to be a promising method for treating nitrate and salt enriched ion-exchange spent brine. However, the influencing mechanisms of salinity in MBfRs are rarely deeply discussed from a microbiological perspective. In this study, the dynamics of the microbial community and functional genes in response to salt stress in an MBfR system were comprehensively evaluated. As salinity increased, the MBfR achieved a NO3- -N effluent concentration of 0.0 mg L-1 and a NO2- -N effluent concentration of 18.0 mg L-1 at 5 % salinity from an influent with 50 mg L-1 NO3- -N. Significantly higher salinity (7 %) led to complete inhibition of nitrate reduction. Community analysis indicated that Thauera was the dominant genus at 0 % and 1 % salinity, and Azoarcus showed high salinity tolerance from 3 to 7 % salinity. Pearson analysis proved the significant negative correlation between salinity and the expression of cbbM instead of cbbL. Thus, high salinity changed inorganic carbon fixing and the denitrification process in the MBfR. This work provides a foundation for the practical application of MBfRs with nitrate and salt-enriched wastewater treatment.

A hydrogen-based membrane biofilm reactor (H2-MBfR) was operated to investigate the bioreduction of antimonate [Sb(V)] in terms of Sb(V) removal, the fate of Sb, and the pathways of reduction metabolism. The MBfR achieved up to 80% Sb(V) removal and an Sb(V) removal flux of 0.55 g/m2·day. Sb(V) was reduced to Sb(III), which mainly formed Sb2O3 precipitates in the biofilm matrix, although some Sb(III) was retained intracellularly. High Sb(V) loading caused stress that deteriorated performance that was not recovered when the high Sb(V) loading was removed. The biofilm community consisted of DSbRB (dissimilatory Sb-reduction bacteria), SbRB (Sb-resistant bacteria), and DIRB (dissimilatory iron-reducing bacteria). Dissimilatory antimonate reduction, mediated by the respiratory arsenate reductase ArrAB, was the main reduction route, but respiratory reduction coexisted with cytoplasmic Sb(V)-reduction mediated by arsenate reductase ArsC. Increasing Sb(V) loading caused stress that led to increases in the expression of arsC gene and intracellular accumulation of Sb(III). By illuminating the roles of the dissimilatory and cytoplasmic Sb(V) reduction mechanism in the biofilms of the H2-MBfR, this study reveals that the Sb(V) loading should be controlled to avoid stress that deteriorates Sb(V) reduction.