Environmental Technology最新文献

Phenolic compounds are hazardous industrial pollutants due to their acute environmental toxicity. This study investigates the degradation of 4-chlorophenol (4-CP) using an Ozone Plasma Nanobubble Reactor (OPNR) under varying gas flow rates (1-5 L/min), voltages (10 and 17 kV), and initial 4-CP concentrations (50 and 250 mg/L). The results showed that at an initial 4-CP of 50 mg L^-1 and oxygen flow rate of 4L min^-1, the process at voltages of 5, 10, and 17 kV for 30 minutes resulted in 4-CP degradation of 33.96, 100, and 99.98% respectively. The process using oxygen generated higher 4-CP degradation percentage values (up to 100%) than that using free air input (up to 89.01%). The process at a voltage of 17 kV and various oxygen gas flow rates of 1, 2, 3, 4, and 5 L min^-1 for 60 minutes resulted in 4-CP degradation of 99.80, 99.90, 99.93, 100, and 99.66% at an initial 4-CP of 50 mg L^-1 and then 89.01, 99.60, 99.84, 98.91, and 99.55% at an initial 4-CP of 250 mg L^-1. Therefore, the highest 4-CP degradation using oxygen input by using a voltage of 17 kV for 60 minutes with initial concentrations of 50 mg L^-1 and 250 mg L^-1 was 100% (using oxygen flow rate of 4L min^-1) and 99.60% (using oxygen flow rate of 2L min^-1), respectively. It shows that the OPNR reactor can work optimally.

The substances in ecosystems flow along the food chain. Therefore, we should establish a monitoring system for antibiotic resistance genes (ARGs) in fertilizer products as soon as possible to regulate the use of fertilizers. In this study, three groups of cattle manure organic fertilizers were set up according to the ratio of straw addition, namely CK: cattle manure: straw = 6:4; M1: cattle manure = 100%; M2: cattle manure: straw = 8:2. All groups were supplemented with microbial agents. Their effects on ARGs, class 1 integron integrase genes (intI1) and bacterial communities were investigated. At the end of composting, the relative abundance of sul1, sul2, tetG, and intI1 in M1 and M2 were significantly lower than that in the CK group, and most of the ARGs in each group were removed. The changes in the relative abundance of ARGs are related to changes in microbial community structure. The establishment of temperature conditions is a key factor affecting the structure of microbial communities. Bacillus may play an important role in controlling the relative abundance of ARGs. We found that the most suitable ratio of cattle manure to straw was 8:2 among the three groups, which not only ensured the balanced nutritional composition of organic fertilizers, but also effectively reduced the abundance of ARGs.

Potassium ferrate (K₂FeO₄) has been widely applied as a pretreatment agent for residual sludge digestion, but the complete synthesis of its solid form is costly. In this study, the use of ferrate anode solution (FAS) was examined as a more economical alternative. FAS is generated as an intermediate byproduct during the electrolytic production of solid K₂FeO₄. The performance of FAS was compared with that of conventional solid K₂FeO₄ to assess their respective effects on anaerobic acid production and sludge dewatering. The results indicate that sludge soluble chemical oxygen demand (SCOD) was increased to 3807 mg/L at the low dosage of 10 mL/L, and the production of short-chain fatty acids (SCFAs) reached 2142 mg COD/L. At this dosage, higher efficiencies in protein and polysaccharide release were achieved compared with high-dose K₂FeO₄ (0.5 g/g TSS). Sludge settling and dewatering properties were also improved, and reductions of 9.1% in sedimentation ratio and 9.7% in cake moisture content were achieved during pretreatment. These findings suggest that FAS, as an intermediate byproduct, can replace solid K₂FeO₄ for sludge pretreatment because of its high efficiency at low dosages and its distinct enhancement of dewatering performance. FAS may therefore serve as a more economical and effective option.

In this study, we investigated the impact of applied current, charge loading, initial pH, EC time, and packed-bed reactor density on total arsenic removal from groundwater (GW) in a scrap iron-based batch electrocoagulation (EC) process. The best operating conditions to achieve over 93% total arsenic removal for GW₁ and GW₂ were identified as follows: i = 50 mA, q = 1.25 C/L (7.77 F/m³), pH = 7.6, m_b = 40 g Fe/L, and t_EC = 10 min for GW₁; and i = 100 mA, q = 5.0 C/L (3.1 F/m³), pH = 7.1, m_b = 40 g Fe/L, and t_EC = 25 min for GW₂. GW treated with the EC process shows that arsenic does not pose a risk to humans and does not increase the likelihood of cancer, as demonstrated by chronic daily intake (CDI), hazard quotient (HQ), and carcinogenic risk (CR) analyses. The sludge produced after the EC process was examined using Scanning Electron Microscopy (SEM), which revealed a dense and porous structure. Energy Dispersive X-ray (EDX) analysis confirmed effective treatment, as evidenced by the accumulation of arsenic and iron. Furthermore, a comprehensive evaluation was conducted to assess the arsenic removal capacity, energy consumption, total operating costs, and kinetic analysis. The results show that the EC reactor using scrap iron is a reliable approach for treating GW contaminated with arsenic.

Photosynthetic bacteria (PSB) present a sustainable approach for wastewater treatment by converting organic pollutants into valuable biomass using solar energy. However, conventional photobioreactor (PBR) fail to optimize PSB's photoheterotrophic metabolism under natural illumination. This study bridges critical gaps by systematically evaluating four pilot-scale PBRs (raceway pond, cylindrical, flat-panel, tubular) for PSB-driven sugar wastewater treatment to optimize reactor geometry, light provision, and resource recovery. Results showed that tubular PBRs performed best in biomass yield and daily productivity at batch mode. In outdoor pilot semi-batch operation, the tubular PBR group showed the highest biomass production (3488.4 mg/L) and COD removal (99.0%). The highest carbon recovery ratio (31.5-51.2%) was also obtained in the tubular PBR group, surpassing flat-panel and cylindrical designs by 12.6-118.6%. These findings highlight the potential of tubular PBRs for scalable, light-driven wastewater treatment and establish design principles to balance organic load, light penetration, and metabolic efficiency under natural conditions. This study lays the foundation for the application of photosynthetic bacteria in industrial-scale wastewater resource recovery and holds great significance for advancing sustainable biotechnology.

Fungal laccases are eco-friendly biocatalysts capable of oxidizing a broad spectrum of compounds. In this study, four fungal species were cultivated to evaluate laccase production and their application in the bioremediation of acetaminophen and diclofenac. Among these, Pycnoporus sanguineus exhibited the highest laccase activity (1116.94 U/mL). SDS-PAGE profiling of laccase crude extracts (LCEs) revealed multiple protein bands, while zymograms confirmed the presence of distinct isoforms. Stability assays demonstrated that glycerol protected laccase activity in a concentration- and source-dependent manner, with laccase from Trametes sp. 50/08 showing the most gradual decline over 60 days. When examining the efficacy of bioremediation, the LCE from Marasmiellus palmivorus at 10 U/mL achieved 96% acetaminophen removal within 24 h, whereas the LCE from Agaricus blazei at 30 U/mL was the most effective for diclofenac, achieving 82% removal. However, increasing laccase concentration did not enhance pharmaceutical degradation, suggesting possible substrate saturation or inhibition. These findings highlight the efficiency of crude enzyme extracts in removing acetaminophen and diclofenac, reinforcing their potential as sustainable tools for treating pharmaceutical pollutants in aquatic environments.

Selenium(IV) (Se(IV)) supplementation was evaluated as a biostimulant to enhance m-dichlorobenzene (m-DCB) biodegradation in laboratory-scale biotrickling filters (BTFs) inoculated with Brevibacillus agri DH-1. An optimal Se(IV) concentration of 4.0 mg/L increased steady-state m-DCB removal efficiency from 74.38% to 81.74% at an empty bed residence time (EBRT) of 90 s. When the EBRT was reduced to 30 s, BTF2 maintained a 41.74% removal efficiency, compared with only 17.64% for BTF1. Se(IV) promoted extracellular polymeric substance production, strengthened biofilm adhesion, enhanced catechol-1,2- and catechol-2,3-dioxygenase activities, and moderated surface charge to favour microbial aggregation. Fourier-transform infrared spectroscopy confirmed Se(IV)-facilitated dechlorination and aromatic-ring cleavage, while 16S rRNA sequencing revealed enrichment of key degraders including Brevibacillus, Pseudomonas, Bacillus, Rhodanobacter, and Sphingobium. These findings demonstrate a novel micronutrient-based strategy to improve BTF performance for treating chlorinated aromatic exhaust gases.

Per- and polyfluoroalkyl substances (PFASs) are bioaccumulative and highly stable in ecosystems, posing potential toxicity risks to human health. Membrane treatment has become a critical research area in current treatment technologies for PFASs. In this study, we selected five commercial nanofiltration (NF) membranes to investigate the performance of the membrane structure on treating 30 PFASs in simulated and industrial wastewater. The results indicated that the rejection of 30 PFASs exceeded 65% for all membranes. The performances of NF90 and DK membranes were better than others, whereas the treatment efficiency of the NF270 membrane was the lowest for most PFASs. Under the experimental conditions, NF90 membrane exhibited the highest surface negative charge and the lowest molecular weight cut-off (MWCO), resulting in relatively stronger electrostatic repulsion and size exclusion effects, which were the key factors influencing PFASs removal efficiency. For all membranes, the rejections were higher for PFASs with long carbon chains and strong hydrophobicity. The treatment efficiencies were higher for PFSAs with smaller pK_a and LogK_ow, compared to PFCAs with the same carbon chain length, showing that electrostatic repulsion and hydrophobic interactions resulted in better efficiency. Furthermore, coexisting pollutants in the actual wastewater could have different impacts on the treatment outcomes by influencing factors such as pH and blocking membrane pores. This work presents an environmentally friendly and efficient method for removing PFASs from wastewater and provides insights into the separation mechanism of NF membranes for dozens of PFASs.

This study investigates the anaerobic co-digestion of swine manure and animal by-products to enhance biogas production and nutrient-rich digestate, compared with mono-digestion of swine manure. The co-digestion performance was assessed in different reactor configurations at different mixing ratios. Swine manure and carcasses were collected and pre-treated, then submitted to tests to determine biogas production potential. The co-digestion performance was assessed in different reactor configurations (CLB and CSTR) changing carcasses/manure ratios. Results demonstrated that co-digestion improved gas productivity. In the CSTR, biogas productivity increased from 0.41-1.63 L_Nbiogas L_reactor^-1 d^-1, while methane productivity increased from 0.24-1.03 L_NCH4 L_reactor^-1 d^-1. In the CLB, biogas productivity rose from 0.19-0.61 L_Nbiogas L_reactor^-1 d^-1, with methane productivity increasing from 0.12-0.38 L_NCH4 L_reactor^-1 d^-1. Stability was maintained throughout the experiment, with a notable rise in total ammonia nitrogen (TAN) and a stable pH due to effective buffering capacity. In the CSTR, TAN reached 3.8 gN·L⁻¹ with free ammonia concentrations of approximately 500 mgN·L⁻¹, while in the CLB TAN stabilised at 2.5g N·L⁻¹ with free ammonia consistently below 50 mgN·L⁻¹. Microbial analysis revealed differences between mono-digestion and co-digestion. Co-digestion favoured a diverse community, which significantly contributed to biogas production. Co-digestion also resulted in higher nitrogen and phosphorus concentrations in the digestate compared with mono-digestion, due to the nutrient content of the added carcass material. The study confirms that co-digestion not only enhances biogas production but also produces nutrient-rich digestate, making it a viable and environmentally friendly waste management solution.

This study presents a comprehensive characterisation of sludge generated from chicken processing industry wastewater (CPW) treated by two advanced methods: electrochemical treatment using iron (Fe) electrodes and chemical coagulation employing alum and polymeric flocculants (Rishfloc 8163, Telfloc 5630). Using a suite of analytical techniques - FTIR, SEM-EDX, TEM, Raman, NMR, XRD, TGA, ICP-OES and nutrient profiling - the chemical, structural, and reuse properties of the resulting sludges were elucidated. Electrochemical treatment produced a compact, iron-rich sludge with low ionic contamination, dominated by amorphous iron hydroxides formed via in situ electrode dissolution. In contrast, chemical coagulation resulted in a lighter, porous sludge containing alum residues and polymeric materials, reflected in higher salinity and conductivity. EDX confirmed dominant iron and oxygen in electrochemical sludge, while chemical sludge showed aluminum and silicon signatures. FTIR and Raman analyses indicated more advanced organic degradation in electrochemical sludge, with distinct iron oxide bands and reduced organic complexity. TEM revealed nanostructured iron particles in electrochemical sludge versus larger amorphous aggregates in chemical sludge. Nutrient analysis demonstrated agronomic potential in both, although chemical sludge contained higher nitrogen and phosphorus. Heavy metal content was within safe limits for reuse. This study underscores the advantages of electrochemical treatment in producing stable, nanostructured sludge suitable for sustainable agro-industrial applications, while recommending further risk assessment for long-term soil health impact.