Improved Short-Chain Fatty Acids Production and Protein Degradation During the Anaerobic Fermentation of Waste-Activated Sludge via Alumina Slag-Modified Biochar.

As the by-product in the biological sewage treatment, waste-activated sludge (WAS) always suffers from the difficulty of disposal. Anaerobic fermentation to achieve valuable carbon sources is a feasible way for resource utilization of WAS, whereas the process is always restricted by its biochemical efficiency. Hence, the WAS was used as the feedstock in this study. Alumina slag-modified biochar (Al@BioC) respectively from pine wood (PW) or fresh vinegar residue (FVR) was employed to stimulate the process of short-chain fatty acids (SCFAs) production during the anaerobic treatment of WAS. The results indicate that the addition of Al@BioC could facilitate the distinct increase in SCFAs yield (42.66 g/L) by 14.09% and acetate yield (33.30 g/L) by 18.77%, respectively, when compared with that in regular fermentation without Al@BioC addition. Furthermore, protein degradation was also improved. With the Al@BioCPW added, the maximum concentration of soluble protein reached 867.68 mg/L and was 24.39% higher than the initial level, while the enhancement in the group with Al@BioCFVR and without biochar addition was 12.49% and 7.44%, respectively. According to the results of 16S rDNA sequencing, the relative abundance of acid-producing bacteria (Bacteroidota and Firmicutes) was enriched, enhancing the pathways of protein metabolisms and the ability to resist the harsh environment, respectively. Moreover, Proteiniphilum under Bacteroidota and Fastidiosipila under Firmicutes were the main microorganisms to metabolize protein. The above results might provide a novel material for harvesting the SCFAs production, which is conducive to harmless disposal and carbon resource recovery.

Anti-fouling PVDF membranes incorporating photocatalytic biochar-TiO2 composite for lignin recycle.

In this study, a photocatalytic biochar-TiO2 (C-Ti) composite was prepared using lignin as carbon precursor, and blended with PVDF polymer to fabricate PVDF/C-Ti MMMs via non-solvent induced phase inversion. The prepared membrane demonstrates both 1.5 times higher initial and recovered fluxes than the similarly prepared PVDF/TiO2 membrane, suggesting the C-Ti composite can help maintain higher photodegradation efficiency and better anti-fouling performance. In addition, the comparison of PVDF/C-Ti membrane against pristine PVDF membrane show that the reversible fouling and photodegradation reversible fouling of BSA increased from 10.1% to 6.4%-35.1% and 26.6%, respectively. And the FRR of PVDF/C-Ti membrane was 62.12%, 1.8 times that of PVDF membrane. The PVDF/C-Ti membrane was also applied for lignin separation, where the rejection to sodium lignin sulfonate was maintained at about 75%, and the flux recovery ratio after UV irradiation reached 90%. The demonstrated the advantages of PVDF/C-Ti membrane in photocatalytic degradation and antifouling performance.

Designing Multi-Stage 2 A/O-MBR Processes for a Higher Removal Rate of Pollution in Wastewater.

Multi-stage A/O-MBR processes were designed to improve wastewater treatment efficiency; three different designs were carried out and compared in this study. The 2(A/O)-MBR process, i.e., with two sets of anoxic/oxic tanks in series, showed better effluent quality than A/O-MBR and 3(A/O)-MBR processes. The removal rates of COD, NH4+-N, TP and TN were 95.29%, 89.47%, 83.55% and 78.58%, respectively, complying satisfactorily with China's urban sewage treatment plant pollutant discharge standards. In terms of membrane fouling, the 3(A/O)-MBR process demonstrated the lowest fouling propensity. The microbial community structure in each bioreaction tank was analyzed, the results from which matched with the process efficiency and fouling behavior.

Relieving ammonia inhibition by zero-valent iron (ZVI) dosing to enhance methanogenesis in the high solid anaerobic digestion of swine manure.

Relieving from ammonia inhibition and enhancing the utilization of thermodynamically unfavorable propionate are crucial for methane harvest in the high solid anaerobic digestion (HSAD) of ammonia-rich swine manure. In this study, the potential of dosing zero-valent iron (ZVI, 150 um) for enhancing the methanogenesis to resist total ammonia (TAN) over 5.0 g-N·L-1 was investigated via batch experiments under mesophilic condition. The cumulative methane production was enhanced by 22.2% at ≥160 mM ZVI dosage and the HSAD duration was further shortened by 50.6% at ≥320 mM ZVI dosage. The enhanced methanogenesis was mainly resulted from the full utilization of propionate and the accelerated collapse of posterior-biodegradable organics which might be driven by ZVI. Results of microbial community and qPCR (mcrA) showed that ZVI might trigger the blooming of Methanosarcina (from 27.9% to 78.3%) and Syntrophomonas (0.5% to 3.7%) and attribute to their possible direct interspecies electron transfer (DIET) to enhance propionate utilization. Besides, the main methanogenesis might remain in the effective aceticlastic pathway even under free ammonia (FAN) almost 1.0 g-N·L-1 because syntrophic acetate oxidizing bacteria (SAOB) decreased to almost none at 320 mM ZVI dosage. Dosing ZVI could relieve HSAD from TAN inhibition and more dosage was required to resist FAN inhibition.

Photoprotection of maqui berry against ultraviolet B-induced photodamage in vitro and in vivo.

Ultraviolet B (UVB) irradiation-induced DNA damage, oxidative stress, inflammatory processes, and skin pigmentation cause pigmented spots, wrinkles, inflammation, and accelerated skin aging and cancer. Maqui berry (Aristotelia chilensis) is a natural antioxidant, anticancer, and anti-inflammatory food. We investigated the photoprotective properties of the ethyl acetate fraction of maqui berry ethanol extract (MEE) in vitro and in vivo. Spectrophotometric measurements revealed dominant extinction profile of MEE in the UVB range. MEE clearly reversed the DNA damage induced by UVB irradiation in HaCaT cells by upregulating endogenous cellular enzymatic and non-enzymatic antioxidant systems containing superoxide dismutase, catalase, and glutathione and reducing the production of nitric oxide. Moreover, MEE treatment enhanced the antioxidant ability and weakened lipid peroxidation in BALB/c mice exposed to UVB radiation. It also down-regulated interleukin (IL)-6 and tumor necrosis factor-α levels and up-regulated IL-4 levels. Moreover, MEE inhibited the UVB-triggered activation of ERK and p38 MAPK. These data suggest that MEE is an effective agent against UVB-induced photodamage.

[Enhancement for Anaerobic Digestion of Waste Activated Sludge Based on Microwave Pretreatment Combined with Zero Valent Iron].

In this study, we investigated the enhanced performance after addition of zero valent iron (ZVI) under different dosages (low range of 5.19-41.51 g·kg-1 TS and high range of 83.35-853.46 g·kg-1 TS), combined with microwave (MW) pretreatment for anaerobic digestion (AD) of waste activated sludge (WAS). The results demonstrated that the methane production potential of WAS could be increased by 17%-24% with the addition of ZVI combined with MW pretreatment, and especially the methane production rate was enhanced in the initial days (1-4d). ZVI addition could further improve the enhanced performance of AD under MW pretreatment. Compared with the performance of AD with only MW pretreatment, the methane production potential was increased by 7.42%, and methane production flow rate at 2 d was increased by 11.02% with 31.13 g·kg-1 TS of ZVI addition. However, the higher dosage of added ZVI did not show further enhanced performance. It was concluded that ZVI addition promoted the release of dissolved organics at the initial stage of AD. For instance, soluble proteins were increased by 21.16% with the ZVI addition of 31.13 g·kg-1 TS compared with pretreated WAS without ZVI addition. Furthermore, ZVI addition accelerated the degradation of acetic acid, iso-butyric acid, and iso-valeric acid, and led to a significant reduction of orthophosphate and sulfate in the supernatant of the digested sludge. The concentration of iron in the supernatant decreased even with a high dosage of ZVI. Thus, the formation of precipitate that occurred due to reactions between iron and orthophosphate or sulfate, may be the main reason for the lack of enhanced performance even with high dosage of ZVI addition.

Screening and quantitation of residual antibiotics in two different swine wastewater treatment systems during warm and cold seasons.

Due to many occurrences of the illegal addition, misuse and abuse of antibiotics in the swine industry in China, high-resolution mass spectrometry (HRMS) was used to screen and identify these materials in two swine wastewater treatment systems (Swine farm 1: anaerobic digestion - lagoon treatment; Swine farm 2: anaerobic digestion - anoxic treatment - aerobic biological treatment). The results showed that 11 out of 115 antibiotics, including tetracyclines (tetracycline, oxytetracycline, chlortetracycline), sulfonamides (sulfadimidine (SDMD)), macrolides (clarithromycin, tilmicosin (TILM)), fluoroquinolones (ciprofloxacin, ofloxacin, enrofloxacin), ß­lactam (penicillin G), and lincosamides (lincomycin), were identified in the swine farms by screening and confirmation methods through HRMS. The quantification method was carried out using triple-quadrupole tandem mass spectrometry, and the recoveries of 11 analytes in the swine wastewater were above 50%. The investigation results showed that the amount of antibiotic residues during the cold season was much higher than that during the warm season. Among the antibiotics, tetracyclines (average of 58%) were the main antibiotic residues in the two swine farms, with TILM second (33%). Sulfonamides (SDMD) existed only in SF1 and accounted for 10% of the total antibiotic concentration. The average proportion of total antibiotics in the solid and liquid phases were 98.5% and 1.5%, respectively, indicating that antibiotics were mainly adsorbed onto solids, though only SDMD remained relatively high in the liquid phase (5.29%). The degradation data of most of the antibiotics detected in the liquid phase during the wastewater treatments well fitted the simple first-order kinetic model in both SF1 and SF2, and the half-lives of the analytes in SF2 were much shorter than those in SF1. After the wastewater treatment process, approximately 80% of the antibiotics could be removed, but sulfonamides remained at a relatively higher percentage and were the main antibiotics in the effluent (approximately 60%).

Effects of endogenous inhibitors on the evolution of antibiotic resistance genes during high solid anaerobic digestion of swine manure.

Livestock manure is a reservoir of antibiotic resistance genes (ARGs). The endogenous inhibitors that emerge during high solid anaerobic digestion (HSAD) greatly influence the bioprocess performance and the ARGs. The effect of endogenous inhibitors including volatile fatty acids (VFAs) and free ammonia (FA) on the ARG occurrences during HSAD of swine manure was investigated in this study. The ARG properties during HSAD (8%-14% total solids (TS)) largely differed from the low TS control (4%). The endogenous inhibitors and microbial communities greatly contributed to the three-phase changes in ARGs. The concentrations of VFAs and abundances of Proteobacteria and intI1 were correlated with the changes in ARGs. FA inhibition and VFA accumulation (especially propionate) delayed and restricted the decline of ARGs. The relatively slow rate of changes in ARGs and high ARGs in the end product suggested the high risk of the HSAD digestate for land application.

Formation and characteristics of a ternary pH buffer system for in-situ biogas upgrading in two-phase anaerobic membrane bioreactor treating starch wastewater.

Biochemical biogas upgrading retaining more CO2 from biogas to form biomethane opens new avenues for sustainable biofuel production. For developing this technology, maintaining sustain pH for CO2·H2O is fundamental. This study proposes an innovative control strategy for in-situ biogas upgrading retaining and converting the CO2 in the biogas into CH4, via hydrogenotrophic methanogenesis without external agent. The Biogas-pH strategy limited pH drop over 7.4 by stop feeding and maintained the methanogenesis activity by biogas flow rate over 98 ml·h-1. Low pH (7.37-7.80) decrease CO2·H2O as a substrate in stage-I, higher pH (7.40-8.41) enhances CO2 to CO2·H2O transfer by 6.29 ±â€¯2.20% in stage-II. Because of that 95% CO2·H2O converts to HCO3- and CO32- when pH > 7.9, higher pH > 7.9 did not further upgrading the biogas. The carbonate buffer system shown open and close system characteristics in gas and liquid phase. The biogas CH4 was upgraded from 67.27 ±â€¯5.21% to 73.56 ±â€¯5.01%.

Impacts of zero valent iron, natural zeolite and Dnase on the fate of antibiotic resistance genes during thermophilic and mesophilic anaerobic digestion of swine manure.

This study investigated the fate of antibiotic resistance genes (ARGs) during mesophilic (mAD) and thermophilic digestion (tAD) of swine manure through zero valent iron (ZVI), natural zeolite and Dnase addition. Changes of microbial community, intI1, heavy metal resistance genes (MRGs) and virulence factors (VFs) were followed to clarify the influencing factors to ARGs reduction. Results showed that AD could realize ARGs reduction with tAD superior to mAD, and ZVI and natural zeolite could further enhance the reduction, especially for natural zeolite addition at mAD. The reduction efficiency of the relative abundance of ARGs was increased by 33.3% and 138.5% after ZVI and natural zeolite addition, respectively, but Dnase deteriorated ARGs reduction at mAD. Most of ARGs could be reduced effectively except sulII and tetM. Network analysis and partial redundancy analysis indicated that co-occurrence of MRGs followed by microbial community contributed the most to the variation of ARGs fate among treatments.

Protective effects of Coptis chinensis inflorescence extract and linarin against carbon tetrachloride-induced damage in HepG2 cells through the MAPK/Keap1-Nrf2 pathway.

Coptis chinensis inflorescence is traditionally used as tea and has been popular in the local market. C. chinensis inflorescence extract (CE) exhibits protective effects against carbon tetrachloride (CCl4)-induced damage, but the underlying mechanism remains unclear. The main chemicals of CE were detected, purified, and identified in this study. CE and linarin could reverse changes in cell viability, decrease alanine aminotransferase and aspartate transaminase levels, and reduce reactive oxygen species (ROS) generation induced by CCl4 in HepG2 cells. CE and linarin could also phosphorylate mitogen-activated protein kinases (MAPKs) and up-regulate Kelth-like ECH-associated protein (Keap1). The pathways of MAPKs and Keap1 lead to the separation of Keap1 and nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Free Nrf2 transferred to the nucleus and enhanced the expression of phase II detoxification enzymes. This study provides a scientific basis for the use of C. chinensis inflorescence, which exhibits a hepatoprotective function, as a supplement in the food industry.