Environmental Technology & Innovation最新文献

Stacking edge-of-field practices may improve nutrient removal from crops. To examine the effects of stacking edge-of-field conservation practices, a woodchip bioreactor (WBR) and saturated riparian buffer (SRB) were installed in series by intercepting tile flow from a field having a drainage water management system. Nutrient monitoring from 5 years evaluated nutrient export annually and based on the precipitation intensity. Drainage water was monitored for total suspended solids (TSS), nitrate-N, total-P, total-N, and ortho-P at the inlet and outlet of WBR and control structure of SRB. Nutrient export reductions of WBR and SRB were determined for precipitation events that were categorized as low <12.7 mm, mid 12.7–25.4 mm, high 25.4–50.8 mm, and very high >50.8 mm. Over the five seasons, nitrate-N export was reduced 88 % at the WBR outlet and 78 % at SRB outlet when used in a stacked series configuration. The efficacy of edge-of-field practices was affected by the intensity of precipitation events. The low and mid-intensity precipitation events generated 67 % of the total discharge from the subsurface drainage system which accounted for 74 % of the influent nitrate-N. During low and mid-intensity precipitation events, discharge was reduced by 58–65 %, nitrate-N was reduced by 49–88 % and total-P was reduced by 65–73 % by using stacked practice of WBR and SRB. During high and very high-intensity precipitation events only nitrate-N export was reduced by 61–66 %. This indicates that when designing stacked edge-of-the-field practices the cumulative effect of the practices and their performance during different precipitation events should be taken into account when managing conservation practice-based cropping systems.

This study modified and integrated a bioimaging method of hybridization chain reaction fluorescence in situ hybridization (HCR-FISH) into a pipeline for assessing biofouling on stainless steel (SS). A modified protocol of double-labeling HCR-FISH was directly applied to two surface types of SS grade EN 1.4404 to detect localized bacteria and sulfate-reducing bacteria (SRB) by targeting bacterial 16 S rRNA genes and dissimilatory sulfite reductase (dsrB) genes, respectively. The protocol was first validated using microbial pure cultures and materials before being integrated into a biofouling assessment pipeline of SS in a laboratory-scale brackish water circuit, incorporating electrochemical, surface, and molecular biology characterization analyses. The double-labeling HCR-FISH improved bioimaging of surface biofilm morphology and microbial distribution, surpassing monochrome staining methods. This method was compatible and complemented other microscopy techniques and molecular biological analyses, providing additional insights into the biofilms and deposits on the alloy surfaces. The implemented assessment pipeline for biofouling determination frequently detected the ennoblement phenomenon in the evolution of marine biofilm on SS surfaces. However, within the experimental timeframe, microbial activities in the brackish seawater circuit did not flourish significantly, resulting in minimal impact on the steel material. Additionally, surface type and roughness may correlate with microbial adhesion, biofilm growth, and the deformation of passivation layers in SS. Despite abundant sessile bacteria, particularly opportunistic microorganisms, on the steel surfaces, no direct correlations with biodeterioration phenomena or influences of surface roughness of an alloy and the presence of biofilm were conclusively established.

Soil respiration (R_s) and its temperature and water sensitivities play a vital role in understanding the processes and mechanisms of carbon (C) cycling in half plastic film mulching (M_m) field. A two-year field experiment was conducted to investigate the responses of R_s and its components, including respiration from roots (R_r) and soil free-living microbes (R_m), to soil temperature (ST) and water content (SWC) amidst environmental changes. Results showed that M_m significantly stimulated the cumulative CO₂ emissions of R_m (CE-R_m) and R_r mainly due to the prominent increase of them in rows without plastic film in M_m. This was attributed to more favorable microclimatic conditions under M_m for microbes and roots growth, identified by improved SWC, dissolved organic C (DOC) and total nitrogen (DTN), microbial biomass C (MBC) and nitrogen (MBN) contents, enzyme activities and functional genes abundances associated with C degradation. The combination of ST and SWC can help to more accurately predict the seasonal R_r and R_m variation than solely ST or SWC. M_m considerably increased the temperature sensitivity of R_m and the water sensitivities of R_m and R_r probably due to the improved soil C and nitrogen substrates for microbes and roots indicated by growing DOC and DTN contents. This study indicated that the M_m could sustain crop yield without increasing environmental impacts because there was no significant difference for CE-R_m per unit of grain yield produced between M₀ and M_m.

Approximately 3.2 billion cubic meters of untreated sewer overflow water is discharged into U.S. lakes and rivers every year during high-intensity precipitation events posing both environmental and public health challenges. A decentralized, end-of-pipe sewer overflow treatment system would eliminate detrimental overflow effects by handling peak wet-weather flow and associated pollutant loadings. In this study, an overflow treatment system comprised of suspended solids removal followed by chemical oxidation was assessed. Three different suspended solids removal technologies were employed to determine their compatibility with subsequent ozonation and to estimate the treatment cost to meet Clean Water Act discharge permit requirements for biochemical oxygen demand (BOD), total suspended solids (TSS), and Escherichia coli (E. coli) in approximately 30 minutes of total treatment time. Both cloth media filtration with ozonation and chemically enhanced primary treatment with ozonation met permit limits for BOD, TSS, and E. coli, while conventional primary treatment only met permit limits for BOD and TSS, ostensibly due to lower TSS removal by conventional primary treatment. Initial suspended solids removal was a key parameter for effective, subsequent ozonation to remove BOD, achieve disinfection, and decrease operating costs. The estimated, simple operating cost was competitive with conventional activated sludge ($0.10/m³ water treated, 2022 dollars). A full-scale decentralized, end-of-pipe treatment system could be operated as a “peaker facility” to handle large flows during storm events but remain idle during dry weather periods.

Excessive chemical fertilizers harm the environment, economy, and health, while compost and its extracts provide a sustainable solution. Consequently, the development of liquid organic amendments with biofertilizing and antioxidant capabilities is of significant interest in intensive agriculture. To achieve this, four Compost Extraction Protocols (CEP1–4) were applied to different compost to obtain a range of aqueous extracts. These treatments varied in temperature, incubation duration, and agitation. The raw materials for the compost used were Agri-food Waste (AW), Sewage Sludge (SS), Vegetable Waste (VW), and Olive Mill Waste (OMW). The extracts were characterized in physicochemical terms and their potential to promote radicle germination in cucumber and lettuce seeds. Additionally, counts of microbial groups associated with biofertilizing capacity were conducted. Three extracts were chosen based on the germination index to conduct an in vivo bioassay on seedlings. Finally, oxidative stress in radicles and seedlings resulting from the preceding tests was evaluated by quantifying malondialdehyde (MDA), total phenolic compounds (TPC), and ascorbate-glutathione cycle enzymes. The results established that protocols with milder temperatures, such as CEP1 and CEP4, yielded aqueous compost extracts with good biofertilizing and antioxidant properties, although the effect was dependent on crop sensitivity. Specifically, the extracts selected for the seedling trial, OMW-A CEP4, AW-A CEP1, and especially AW-A CEP4, demonstrated a remarkable biofertilizing and antioxidant properties in lettuce, by increasing growth parameters and TPC while decreasing MDA. The results indicate that aqueous compost extracts are a suitable alternative to reduce the consumption of chemical fertilizers.

Vegetables represent a primary pathway for cadmium (Cd) exposure, posing a serious threat to human health. The utilization of alkalizing bacteria presents an effective means to elevate pH, thereby facilitating the alteration of Cd migration efficiency. This study validated the efficacy of alkalizing bacteria Stenotrophomonas sp. H225 (SH225) in promoting plant growth and reducing Cd accumulation in roots and leaves through hydroponic experiments. It further elucidated the specific mechanisms by which SH225 reduces Cd migration. Results showed SH225 raised pH by up to 0.89 unit under Cd stress and decreased Cd accumulation in roots and leaves by 30.39 % and 66.56 %, respectively. Cd speciation distribution data (including residual, adsorbed, and intracellular forms) demonstrated SH225's capacity to adsorb Cd, resulting in a 16.24 % reduction in residual Cd. SEM and TEM analyses corroborated these findings, illustrating substantial Cd adsorption by SH225 bacterial cell walls folding. Additionally, FTIR results highlighted the involvement of functional groups such as -OH, -NH₂, CH₂/CH₃ bending, COO-, and PO during the adsorption process. In conclusion, the alkalizing bacterium SH225 has restricted the migration of Cd into plant tissues, thereby reducing the health risks associated with Cd exposure.

The exogenous addition of humic acid (HA) is often seen as a biostimulation strategy to expedite the bioremediation of various pharmaceutical pollutants. Nevertheless, the impact of HA on the bioadsorption of ofloxacin (OFL), the main pathway for OFL removal in activated sludge, remains unknown. In this study, the presence of 10 mg/L HA notably decreased the theoretical OFL adsorption capacity from 8.94 to 7.95 mg/g. The inhibitory effect persisted across varying pH and ionic strengths and became more pronounced with increasing HA concentration. The morphological changes on biosolid (BIO) induced by HA indicated that HA was bioadsorbed, which in turn competed with OFL for metal binding sites like Ca and Mg on BIO. Further analysis of the OFL-HA interaction reveals the involvement of hydrogen bonding and electrostatic attraction. The study also demonstrates the bridging role of HA between OFL and BIO through consecutive desorption and re-absorption processes of OFL in the presence of HA. To quantify the direct and indirect adsorption ratios, a new approach was proposed, which determined the mass ratios of direct (OFL:BIO) and indirect bioadsorption (OFL:HA:BIO) as 1:192 and 1:21:854, respectively. These findings suggest that the indirect OFL adsorption through the HA bridge could not compensate for the adverse effects caused by the reduction of metal binding sites. Overall, this study calls for a reassessment of the addition of HA in the bioremediation process of OFL. Considering that HA widely coexists with antibiotics in wastewater, the study also provides valuable insights into OFL removal mechanisms in WWTPs.

The application of membrane bioreactors (MBRs) has emerged as an impressive solution to water scarcity. One of the main obstacles for MBR application is membrane fouling. This work studied the effect of the novel simultaneous application of electric field and positively-charged nano chitosan on membrane fouling. Four MBRs of 1 (control bioreactor), 2 (control bioreactor + electric filed), 3 (control bioreactor + nano chitosan) and 4 (control bioreactor + electric filed + nano chitosan) were evaluated. The results indicated that the concurrent use of voltage and nano chitosan better reduced the membrane fouling, decreased flux decline, and enhanced recovery ratios and membrane bioreactor performance index by nearly 43 % and 84 %, respectively. Meanwhile, the contents of soluble microbial products (SMP) and extracellular polymeric substances (EPS) were reduced from MBR1 to MBR4, respectively. Reduced zeta potential and increased particle sizes led to the change in the cake layer and fouling mitigation from MBR1 to MBR4, as observed through scanning electron microscope (SEM) images. Excitation-emission matrix (EEM) analysis showed that humic acid was adsorbed by both electro-coagulants and nano adsorbents, resulting in a substantial (approximately 97 %) reduction in membrane pore fouling for MBR4. The combination of electrocoagulation, electro-oxidation, and electrophoresis processes, along with adsorption by positively charged nano chitosan, effectively mitigated membrane fouling. The cathode induced a negative charge on sludge particles, subsequently facilitating their adsorption by the positively charged nano chitosan adsorbents. The results demonstrated that combining electric field and nano chitosan effectively suppresses membrane fouling, with relevance for forthcoming technological advancements.

Biological Fe(II) oxidation by iron-oxidising bacteria (FeOBs) at low pH is a cost-effective treatment for acid mine drainage (AMD). However, treatments based on this process are limited because of uncertainties regarding the ability and rate of oxidation of Fe(II) from AMD. In the present study, an indigenous FeOBs consortium was enriched in AMD, and its ability to oxidise Fe(II) is described. The bio-oxidation rate of Fe(II) was 39.1 mg/(L·h) under optimal culture conditions [35 ℃, pH 2.0, 500 mg/L Fe(II)]. In addition, the oxidation rate equation of Fe(II) could be fitted to a zero-order kinetic model, indicating that Fe(II) was oxidised at a constant rate. Furthermore, a continuous-flow bioreactor was developed to simulate the Fe(II) oxidation efficiency of indigenous FeOBs for in situ AMD biological treatment. The maximum Fe(II) oxidation rate was 22.8 mg/(L·h) when the influent Fe(II) load was 32.3 mg/(L·h). Acidithiobacillus and Acidiphilium were the dominant species contributing to Fe(II) oxidation in the bioreactor, accounting for 67.7 % and 32.8 %, respectively. The results will help promote the application of FeOBs in AMD treatment.

The presence of Sb(V) in aqueous solutions poses a significant threat to the surrounding environment, and current treatment methods are inadequate. In this study, a magnetic surfactant (CTAB)-modified iron-calcium composite (CTAB-IC) was successfully synthesized using iron-calcium composite as the base material. This novel composite was used for the efficient removal of Sb(V) from textile wastewater solutions. Characterization analyses revealed that the CTAB-IC material exhibits a rich long-prismatic structure and superparamagnetic properties, classifying it as a soft magnetic material. Post-adsorption particle agglomerates were found to comprise Ca, S, and O. Sequential batch experiments demonstrated a maximum adsorption capacity of 54.05 mg/g, with adsorption kinetics data fitting the pseudo-second-order model. The intraparticle diffusion model indicated the presence of multiple diffusion steps during the adsorption process. Additionally, the adsorption of Sb(V) by CTAB-IC was identified as a heterogeneous surface adsorption process, best described by the Freundlich model. The primary adsorption mechanisms involved the formation of surface Ca-O-Sb complexes and inner-sphere Fe-O-Sb complexes, as well as amorphous surface precipitation and electrostatic adsorption. Notably, the treatment of textile wastewater often results in iron-calcium-rich sludge, which is challenging to manage and valorize. This study explored the potential for resource recycling by utilizing CTAB to harness the Fe elements in textile wastewater sludge, thereby promoting waste-to-resource conversion.