Livestock Wastewater Research Articles

Sustainable design of photo-Fenton-like oxidation process in actual livestock wastewater through the highly dispersed FeCl3 anchoring on a g-C3N4 substrate

Photocatalytic technology emerges as a promising solution for the sustainable treatment of contaminated wastewater. However, the practical implementation of designed photocatalysts often faces challenges due to the intricate ‘high carbon footprint’ process and limited outdoor laboratory investigations. Herein, a simple yet versatile impregnation approach is proposed to anchor highly dispersed FeCl3 on a g-C3N4 substrate (Fe-C3N4) with minimal energy consumption and post-processing. Fe-C3N4 enhances photocatalytic reactivity for antibiotic degradation via a synergistic photo-Fenton-like oxidation technique, efficiently removing antibiotic pollutants from actual livestock wastewater. The Fe-C3N4 catalyst exhibited consistent degradation performance over five cycles in laboratory conditions, maintaining a degradation efficiency exceeding 90 % for tetracycline hydrochloride (TCHCl). Furthermore, we engineered a straightforward Fe-C3N4Na2SiO3 reactor for treating livestock wastewater, achieving an 81.8 % removal of TCHCl in outdoor field tests conducted in the winter and summer in China. The Fe-C3N4 catalyst demonstrated high feasibility in treating antibiotic-contaminated livestock wastewater under year-round climatic conditions, leveraging synergistic effects. The stabilization of Fe-C3N4 for the degradation of antibiotic-containing wastewater under sunlight represents a significant advancement in the practical application of photocatalysts, marking a crucial milestone from experimental conception to implementation. Acute toxicity estimation suggested that intermediates/products generated exhibited lower toxicity compared to TCHCl, indicating their practical applicability. Density functional theory (DFT) analysis successfully predicted significant electron transfer between Fe-C3N4 and TCHCl, indicating efficient interfacial interactions on the TCHCl surface. To ensure the environmental sustainability of Fe-C3N4, a life cycle assessment (LCA) was conducted to compared this photocatalyst with other commonly used emerging photocatalysts. The results demonstrated that Fe-C3N4 exhibits a two orders of magnitude lower CO2 equivalent emission compared to the ZnO photocatalyst, indicating a cost-effective and efficient synergistic photo-Fenton-like catalytic approach. This low-cost photocatalyst, moving from the laboratory to real-world wastewater applications, provides a powerful and more sustainable solution for the efficient treatment of wastewater containing antibiotics from livestock farming.

The culture of Chlorella with livestock wastewater and the application of its oligosaccharides in promoting rice seed germination under high salinity conditions

Algal oligosaccharides, derived from polysaccharides in algal biomass, exhibit bioactive properties that enhance plant antioxidant enzyme activity and free radical scavenging. Currently, algal oligosaccharides are mainly produced from large algae, while studies on preparing algal oligosaccharides from microalgae are relatively insufficient. This study focuses on utilizing Chlorella cultivated under controlled conditions using diluted livestock wastewater to produce algal oligosaccharides and investigates their impact on rice seed germination under salt stress. Results show that culturing Chlorella with diluted livestock wastewater not only stimulated algal growth but also efficiently removed nitrogen, phosphorus, and other nutrients. Algal oligosaccharides demonstrated significant improvements in rice seed germination, vigor indices, biomass accumulation, and nitrogen absorption under salt stress. Physiological indicators revealed elevated osmotic adjustment substances, increased chlorophyll content, and alleviated oxidative damage in rice seedlings treated with algal oligosaccharides. The study introduces an innovative method of using livestock wastewater for algal oligosaccharides production, emphasizing its dual benefits including efficient resource utilization and significant cost reduction. The findings also support the theoretical application of Chlorella-derived algal oligosaccharides in enhancing rice cultivation under salt stress.

Elucidating the function of MgO precursors on the adsorptive removal and recovery of water phosphorus

Phosphorus (P) recovery with MgO-based adsorbents (MBA) is an effective method for water management and eutrophication prevention. However, the function of MgO precursors on the adsorptive removal and recovery of water P has not yet been sufficiently studied. Therefore, five distinct precursors, namely MgCl2·6H2O, Mg(NO3)2·6H2O, Mg(CH3COO)2·4H2O, Mg(OH)2, and Mg5(OH)2(CO3)4·xH2O, were employed to synthesize MgOs, resulting in the formation of corresponding calcination products identified as CH-MgO, NI-MgO, AC-MgO, HY-MgO, and BC-MgO, respectively. The surface morphology, Brunauer-Emmett-Teller specific surface area (SBET), total pore volume (TPV) and average pore size (APS) of the MgOs were impacted by their precursors, which affected their ability for P recovery. The flower-like BC-MgO showed the highest adsorption capacity (mg P/g) for P (426.2), followed by AC-MgO (398.1), CH-MgO (329.5), HY-MgO (296.6), and then NI-MgO (274.9). BC-MgO recovered 56.2 % of total P (TP) and 61.7 % orthophosphate (ortho-P) from livestock wastewater, and 56.3 % TP and 95.9 % ortho-P from sewage treatment effluent. P adsorption was pH dependent and positively correlated with the adsorbents SBET and TPV. Surface complexation and deposition, ligand exchange, and electrostatic attraction were the main processes involved in P adsorptive capture and its recovery. The leaching of Mg2+ into water was negligible from all studied MgOs, particularly BC-MgO and AC-MgO. The recovered P from the P-loaded BC-MgO enhanced seed germination and root growth and thus might be used in soil as an alternative P fertilizer. Based on those findings we can conclude that BC-MgO showed high potential applications for the removal and recovery of P from wastewater under wide range of water pH and therefore can be used for remediation of P-rich water. Those results are meaningful for MBA engineering application, preventing water eutrophication, producing alternative P fertilizers, and achieving sustainable development goals in future.

Carbapenem-resistant Enterobacterales in wastewater resources and healthy carriers: A survey in Iran

ABSTRACT The carbapenem-resistant Enterobacterales (CRE) pose a pressing public health concern. Here, we investigated the frequency of CRE bacteria, carbapenemase-encoding genes, and the molecular epidemiology of carbapenemase-resistant Escherichia coli in wastewater resources and healthy carriers in Iran. Out of 617 Enterobacterales bacteria, 24% were carbapenem-resistant. The prevalence of CRE bacteria in livestock and poultry wastewater at 34% and hospital wastewater at 33% was significantly higher (P ≤ 0.05) than those in healthy carriers and municipal wastewater at 22 and 17%, respectively. The overall colonization rate of CRE in healthy individuals was 22%. Regarding individual Enterobacterales species, the following percentages of isolates were found to be CRE: E. coli (18%), Citrobacter spp. (24%), Klebsiella pneumoniae (28%), Proteus spp. (40%), Enterobacter spp. (25%), Yersinia spp. (17%), Hafnia spp. (31%), Providencia spp. (21%), and Serratia spp. (36%). The blaOXA-48 gene was detected in 97% of CRE isolates, while the blaNDM and blaVIM genes were detected in 24 and 3% of isolates, respectively. The B2 phylogroup was the most prominent group identified in carbapenem-resistant E. coli isolates, accounting for 80% of isolates. High prevalence of CRE with transmissible carbapenemase genes among healthy people and wastewater in Iran underscores the need for assertive measures to prevent further dissemination.

Synergistic promotion of microalgal growth and copper removal from synthetic wastewater by nanoscale zero-valent iron particles.

The increasing concentrations of heavy metals in livestock wastewater pose a serious threat to the environmental safety and human health, limiting its resource utilisation. In the present study, microalgae and nanoscale zero-valent iron were selected to construct a coupled system for copper-containing wastewater treatment. The addition of 50 mg·L-1 nanoscale zero-valent iron (50 nm) was the optimal value for the experiment, which could significantly increase the biomass of microalgae. In addition, nanoscale zero-valent iron stimulated microalgal secretion of extracellular polymeric substances, increasing the contents of binding sites, organic ligands, and functional groups on the microalgal surfaces and ultimately promoting the settling of microalgae and binding of heavy metals. The coupled system could quickly adapt to copper-containing wastewater of 10 mg·L-1, and the copper removal rate reached 94.99%. Adsorption and uptake by organisms, together with the contribution of zero-valent iron nanoparticles, are the major copper removal pathways. Overall, this work offers a novel technical solution for enhanced treatment of copper-containing livestock wastewater, which will help improve the efficiency and quality of wastewater treatment.

Application of Cotton Stalk as an Adsorbent for Copper(II) Ions in Sustainable Wastewater Treatment

The capacity of untreated cotton stalk to remove and adsorb Cu2+ ions in synthetic and natural aqueous solutions was evaluated. The influence of three sensitive parameters of the adsorption process—solution pH, adsorbent dosage, and contact time—on the percentage of Cu2+ removal in agricultural wastewater, livestock wastewater, and synthetic samples was studied. Physicochemical and morphological properties were studied using thermogravimetry, Fourier infrared spectrophotometry, and scanning electron microscopy. The elemental composition, proximal composition, zero charge point, and acid–base sites were determined. In addition, kinetic studies were performed, and the adsorption equilibrium was analyzed. The optimum conditions for Cu2+ adsorption were the following: solution pH = 5.5, adsorbent dosage of 0.6 g, and contact time of 60 min. Under these conditions, the percentage of Cu2+ removal in synthetic samples was 66.5% when the initial copper concentration was 50 mg/L. The removal percentage in agricultural and livestock wastewater samples was 87.60% and 85.05%, respectively, when the initial copper concentration was 25 mg/L. The adsorption data are consistent with the Freundlich isotherm model, which achieved a quadratic fit of 0.991 compared to 0.5542 for the Langmuir model. The experimental results indicate that the adsorption adequately fits the pseudo-second-order kinetic model. The results suggest that cotton stalks are a promising adsorbent for the ecological and economical removal of Cu2+ in wastewater. This research, therefore, provides relevant information that contributes to the sustainable management of agricultural waste and instills hope for a reduction in water pollution from heavy metals derived from agricultural activities.

Enhanced simultaneous phosphate recovery and organics removal by a nucleation crystallization pelleting process

Naturally co-occurring phosphate (P) and dissolved organic matter (DOM) in raised livestock wastewater have caused increasing public concerns. This study fabricated a novel nucleation crystallization pelleting process (NCP) showing orientated P recovery and HA (as a major fraction of DOM) removal from wastewater. Results showed that after 120 h of continuous operation, the total removal efficiency of P and HA stabilized at 97.5 % and 92 %, respectively, by using a three-stage NCP process. The NCP results further demonstrated that the main recovery mechanism of P involves surface-induced precipitation of P in the form of hydroxyapatite (HAP) on the seed surface by modulating the supersaturation of HAP in the system. The FTIR, SEM-EDS, and XPS analysis combined with DFT calculations revealed the molecular-level mechanisms for removing HA, which were mainly controlled by Calcium ions bridging, H-bonding, and π-π stacking. More importantly, the attached HAP on the seed surface would enhance the mutual interaction with HA, further enhancing the removal efficiency of HA. This contribution not only opens a high potential avenue for further research on the simultaneous capture of P and organic matter but also sheds light on the development of the practical application of the NCP remediation strategies.

Response surface methodology for process optimization in livestock wastewater treatment: A review

With increasing demand for meat and dairy products, the volume of wastewater generated from the livestock industry has become a significant environmental concern. The treatment of livestock wastewater (LWW) is a challenging process that involves removing nutrients, organic matter, pathogens, and other pollutants from livestock manure and urine. In response to this challenge, researchers have developed and investigated different biological, physical, and chemical treatment technologies that perform better upon optimization. Optimization of LWW handling processes can help improve the efficacy and sustainability of treatment systems as well as minimize environmental impacts and associated costs. Response surface methodology (RSM) as an optimization approach can effectively optimize operational parameters that affect process performance. This review article summarizes the main steps of RSM, recent applications of RSM in LWW treatment, highlights the advantages and limitations of this technique, and provides recommendations for future research and practice, including its cost-effectiveness, accuracy, and ability to improve treatment efficiency.

Leveraging wastewater surveillance to detect viral diseases in livestock settings

Wastewater surveillance has evolved into a powerful tool for monitoring public health-relevant analytes. Recent applications in tracking severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection highlight its potential. Beyond humans, it can be extended to livestock settings where there is increasing demand for livestock products, posing risks of disease emergence. Wastewater surveillance may offer non-invasive, cost-effective means to detect potential outbreaks among animals. This approach aligns with the “One Health” paradigm, emphasizing the interconnectedness of animal, human, and ecosystem health. By monitoring viruses in livestock wastewater, early detection, prevention, and control strategies can be employed, safeguarding both animal and human health, economic stability, and international trade. This integrated “One Health” approach enhances collaboration and a comprehensive understanding of disease dynamics, supporting proactive measures in the Anthropocene era where animal and human diseases are on the rise.

Applying fluorescence spectroscopy coupled with Gaussian band fitting to reveal dynamic variation process of humus fractions from riparian soils along an urbanized river

Humus, an important fraction of soil organic matter, play an environmental role on nutrients, organic and inorganic pollutants in riparian zones of urbanized rivers. In this study, dynamic variation process of humus fractions from riparian soils was revealed along Puhe River. Composite soil samples of four depths were collected from four land-uses, i.e., eco-conservation area (ECA), industrial area (INA), urban/town area (UTA), rural/agricultural area (RAA). Based on synchronous fluorescence spectra coupled with Gaussian band fitting, fulvic/humic acid predominantly contained tyrosine-like (TYLF), tryptophan-like (TRLF), microbial-like (MLF), fulvic-like (FLF) and humic-like (HLF) substances within each soil profile. TRLF, MLF and FLF (89.43–90.30 %) are the representative components in fulvic-acid, while MLF and HLF (52.81–59.97 %) in humic-acid. Phenolic, carboxylic and humified materials were present in both humus. According to 2-dimensitonal correlation spectroscopy and canonical correlation analysis, fulvic/humic acid within the ECA soil profile could be mainly derived from the degradations of terrestrial plant metabolites and residuals. Within the INA, fulvic-acid could be associated with treated/untreated wastewater, which entered the river and flew into the riparian during high flow period; whereas humic-acid could be relative to the terrestrials. Fulvic-acid had the same source as humic-acid in the UTA, which might be concerned with scattered domestic sewage and livestock wastewater, rather than the fluvial water. Furthermore, the source of fulvic/humic acid in the RAA was the crop metabolites and residuals, apart from the livestock wastewater. Noticeably, the variations of humus fractions in the ECA and RAA roughly occurred in 0–60 cm, while approximately in 20–80 cm in the INA and UTA. This proved that humus fractions in the former were referred to the plant/crop residuals, whereas humus fractions in the latter were those the terrestrials and fluvial water. This study could provide a key support for the construction and restoration of the urbanized riparian zone.

Environmental health hazards of untreated livestock wastewater: potential risks and future perspectives.

Due to technological and economic limitations, waste products such as sewage and manure generated in livestock farming lack comprehensive scientific and centralized treatment. This leads to the exposure of various contaminants in livestock wastewater, posing potential risks to both the ecological environment and human health. This review evaluates the environmental and physical health risks posed by common pollutants in livestock wastewater and outlines future treatment methods to mitigate these risks. Residual wastes in livestock wastewater, including pathogenic bacteria and parasites surviving after epidemics or diseases on various farms, along with antibiotics, organic wastes, and heavy metals from farming activities, contribute to environmental damage and pose risks to human health. As the livestock industry's development increasingly impacts society's future negatively, addressing the issue of residual wastes in livestock wastewater discharge becomes imperative. Ongoing advancements in wastewater treatment systems are consistently updating and refining practices to effectively minimize waste exposure at the discharge source, mitigating risks to environmental ecology and human health. This review not only summarizes the "potential risks of livestock wastewater" but also explores "the prospects for the development of wastewater treatment technologies" based on current reports. It offers valuable insights to support the long-term and healthy development of the livestock industry and contribute to the sustainable development of the ecological environment.

Reuse of waste casein peptides to capture Cu (II) for long-term antibacterial reutilization

To date, researchers have worked on developing new pathways to control and manage food and industrial wastes (e.g. dairy wastewater, heavy metals, etc.), but most do not involve the reuse of these wastes. Herein, we propose to use casein peptides (CPs) based on dairy waste to capture Cu2+ from industrial wastewater, which is reduced to copper and cuprous oxide nanoparticles (consisting of metallic Cu and Cu2O crystalline phases) distributed on CPs. The prepared product CPs/Cu/Cu2O NPs showed prominent antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as multidrug-resistant bacteria from livestock wastewater through generating reactive oxygen species (ROS) in combination with released Cu2+. The method proposed in this study is also applicable to extract Cu2+ from actual electroplating wastewater for bacterial disinfection. Finally, we achieved the modulation of the composition of Cu/Cu2O NPs loaded on CPs.

Label-free electrochemical sensing platform for sensitive detection of ampicillin by combining nucleic acid isothermal enzyme-free amplification circuits with CRISPR/Cas12a

The residue of ampicillin (AMP) in food and ecological environment poses a potential harm to human health. Therefore, a reliable system for detecting AMP is in great demand. Herein, a label-free and sensitive electrochemical sensor utilizing NH2–Co-MOF as an electrocatalytic active material for methylene blue (MB) was developed for rapid and facile AMP detection by combining hybridization chain reaction (HCR), catalytic hairpin assembly (CHA) with CRISPR/Cas12a. The surface of glassy carbon electrode modified with NH2–Co-MOF was able to undergo HCR independent of the AMP, forming long dsDNA complexes to load MB, resulting in strong original electrochemical signal. The presence of AMP could trigger upstream CHA circuit to activate the CRISPR/Cas12a system, thereby achieving rapid non-specific cleavage of the trigger ssDNA of HCR on the electrode surface, hindering the occurrence of HCR and reducing the load of MB. Significant signal change triggered by the target was ultimately obtained, thus achieving sensitive detection of the AMP with a detection limit as low as 1.60 pM (S/N = 3). The proposed sensor exhibited good stability, selectivity, and stability, and achieved reliable detection of AMP in milk and livestock wastewater samples, demonstrating its promising application prospects in food safety and environmental monitoring.

Characteristics and Risk Assessment of Antibiotic Contamination in Oujiang River Basin in Southern Zhejiang Province

Antibiotic pollution in the environment has a negative impact on ecosystem security. Taking the Oujiang River Basin as an example,high-performance liquid chromatography mass spectrometry(LC-MS)was used to detect the concentration of six classes of 35 antibiotics in the surface water of the southern Zhejiang River Basin. The concentration level and spatial distribution of antibiotics were analyzed,the risk of antibiotics to ecology and human health were assessed using relevant models,and the sources of antibiotics were discussed. The results showed that in 20 sampling sites,a total of four classes of 12 antibiotics were detected,including sulfonamides,quinolones,tetracyclines,and lincosamides. The total concentration was ND-1 018 ng·L-1. The highest detection rate was that of Lincomycin(90.48%),followed by that of sulfapyridine(38.10%). The three antibiotics with the highest average concentrations were ofloxacin(12.49 ng·L-1),Lincomycin(11.08 ng·L-1),and difloxacin(7.38 ng·L-1). Antibiotics in the basin showed mainly spotty pollution,which had large spatial differentiation. The average concentration of antibiotics in the upstream(54.39 ng·L-1)was higher than that mid-downstream(46.64 ng·L-1). The degree of antibiotic pollution from upstream to downstream showed a characteristic of being "sparse in the upstream and dense in the downstream. " This indicated that the concentration of antibiotics in the upstream was significantly different,whereas the pollution degree of antibiotics in the downstream was uniform. The upstream was mainly polluted by health,livestock,and poultry breeding wastewater emissions,and downstream pollution was mainly caused by densely populated activities and the rapid development of economy,trade,and industry. The ecological risk assessment results showed that the upstream site H6 had the highest risk quotient,ofloxacin and enrofloxacin had high risk levels, and lincomycin had a moderate risk level. Health risk assessment results showed that the Oujiang River surface water antibiotics posed no risk to human health.

Contamination Characteristics and Ecological Risk Assessment of Pharmaceuticals and Personal Care Products in Drains Flowing into the Yellow River of Ningxia

Pharmaceuticals and personal care products (PPCPs) are a group of emerging contaminants causing detrimental effects on aquatic living organisms even at low doses. To investigate the contamination characteristics and ecological risks of PPCPs in drains flowing into the Yellow River of Ningxia, 21 PPCPs were detected and analyzed using solid phase extraction and ultra-high performance liquid chromatography-mass spectrometry in this study. All 21 targeted compounds were detected in the drains, with total concentrations ranging from 47.52 to 1 700.96 ng·L-1. Ciprofloxacin, acetaminophen, benzophenone-3, and diethyltoluamide were the more commonly detected compounds, with detection frequencies exceeding 80%. The five highest-concentration PPCPs were acetaminophen, diethyltoluamide, caffeine, benzophenone-3, and levofloxacin, with the maximum concentrations of 597.21, 563.23, 559.00, 477.28, and 473.07 ng·L-1, respectively. Spatial analysis showed that the pollution levels of PPCPs in the drains of the four cities were different, with average concentrations of ∑PPCPs in the order of Yinchuan>Shizuishan>Wuzhong>Zhongwei. The total concentration of PPCPs before flowing into the Yellow River ranged from 124.82 to 1 046.61 ng·L-1. Source analysis showed that livestock and poultry breeding wastewater was the primary source for sulfadiazine and oxytetracycline, whereas medical wastewater was the primary source for levofloxacin and ciprofloxacin. The primary sources of triclocarban and triclosan were domestic sewage and industrial wastewater, whereas the primary source of caffeine and diethyltoluamide was domestic sewage. The pollution of diciofenac, cimetidine, triclocarban, and triclosan in the drains was positively correlated with the regional population and economic development level. The ecological risk assessment indicated that levofloxacin, diclofenac, gemfibrozil, benzophenone-3, and triclocarban posed high risks to aquatic organisms in drains flowing into the Yellow River. It is worthwhile to consider the mixture risk of the PPCPs that exhibited high risk at most sampling sites.

Revealing the differences in metabolisms and nitrogen removal mechanisms of the full and shortcut nitrification-denitrification processes for the treatment of livestock wastewater

The full nitrification-denitrification process (FN) and shortcut nitrification-denitrification process (SN) are both important approaches for treating livestock wastewater. However, most existing studies focus on pollutant removal performance in wastewater treatment, while the differences between the two processes in terms of bacterial communities, metabolic pathways, nitrogen removal mechanisms, and potential pathogen threats have been poorly investigated. In this study, the SN process exhibited lower oxygen demand, reduced sludge production, higher nitrogen removal rate, and lower pathogen threat for treating livestock wastewater. The bacterial communities, the primary participants of pollutant removal in wastewater treatment, were significantly different between the two processes. In the FN process, 15 genera were significantly enriched, including Saccharimonadales, Micropruina, Ferruginibacter, etc. On the other hand, the SN process showed enrichment of 10 genera, including Brachymonas, Tessaracoccus, Ottowia, etc. These enriched genera, such as Brachymonas, Tessaracoccus, and Ottowia in the SN process, were positively correlated with the denitrification genes, facilitating a higher nitrogen removal rate. Moreover, the FN process exhibited significantly higher amino acid metabolism and reproduction-related pathways, contributing to its higher alpha-diversity of the bacterial community. The significantly enriched genes involved in assimilatory nitrate reduction and nitrogen assimilation pathway suggested that nitrogen assimilation played a crucial role in ammonia nitrogen removal, but it also increased sludge production in the FN process. Additionally, the FN process had a higher number and abundance of potential pathogens, indicating a greater pathogen threat. In conclusion, this study provides valuable insights into the differences between the FN and SN processes in terms of bacterial communities, nitrogen removal mechanisms, and potential pathogen threats. It also offers theoretical guidance for adopting appropriate strategies in wastewater treatment.

Ammonia concentration and recovery in an up-scaled electrochemical cell through screening of cation exchange membrane

An intensifying global alarm over excessive total ammonia nitrogen (TAN) calls for innovative recovery strategies. Although electrochemically-driven TAN concentration and recovery have been explored, limited research on upscaling lab-scale advancements with careful system engineering leaves a notable gap in practical application. Here, in the context of implementing an upscaled electrochemical system, we carefully chose a suitable cation exchange membrane to ensure the best ammonium migration, energy efficiency, and stability. Systematically examining the effects of applied current density and loading rate using Neosepta CSE, we achieved final concentrated TAN levels in the receiving catholyte, reaching 836.7 mM (4.4-fold), 778.8 mM (3.5-fold), and 980.4 mM (2.8-fold), with nitrogen flux values of 801, 817, and 955 g-N m−2 d−1 for synthetic, food, and livestock wastewater, respectively, at a current density of 25 mA cm−2 and a loading rate of 2.5 mL cm−2 h−1. Successful upscaling to an 8-cell stack, capable of treating 100 L every 20 h (recovering 207 g-N d−1) of synthetic wastewater, showcases the feasibility of upscaled electrochemical systems for TAN recovery.

Influence of Swine Wastewater Irrigation and Straw Return on the Accumulation of Selected Metallic Elements in Soil and Plants

Treated livestock wastewater reuse for irrigation and straw return in arid regions have become common practices worldwide. However, many uncertainties still exist regarding the effects of the returning straw sizes on heavy metal accumulation in soil and plants under treated livestock wastewater irrigation. In a pot experiment growing maize and soybean, large (5–10 cm), medium (1–5 cm), and small (<1 cm) sizes of wheat straw were amended to assess the changes in Cu and Zn distribution in the rhizosphere, bulk soils, and plants. Groundwater and swine wastewater were used as irrigation water resources. The results showed that irrigation with swine wastewater significantly reduced soil pH and increased the concentration of soil-available potassium. Concentrations of Cu in soil were more sensitive to swine wastewater and straw application than those of Zn in soil. Swine wastewater irrigation increased the accumulation of Cu and Zn in plants with higher concentrations of Zn, while straw return tended to inhibit this increase, especially when a small size of straw was employed. In addition to providing a reference for revealing the interaction mechanism between swine wastewater irrigation and straw return, this study proposes feasible solutions to improve the efficiency of agricultural waste recycling and realize sustainable agricultural development.

Analysis of Antibiotic Resistance Genes in Water Reservoirs and Related Wastewater from Animal Farms in Central China.

This study aimed to explore the phenotype and relationship of drug resistance genes in livestock and poultry farm wastewater and drinking water reservoirs to provide evidence for the transmission mechanisms of drug resistance genes, in order to reveal the spread of drug resistance genes in wastewater from intensive farms in Central China to urban reservoirs that serve as drinking water sources and provide preliminary data for the treatment of wastewater from animal farms to reduce the threat to human beings. DNA extraction and metagenomic sequencing were performed on eight groups of samples collected from four water reservoirs and four related wastewaters from animal farms in Central China. Metagenomic sequencing showed that the top 20 AROs with the highest abundance were vanT_gene, vanY_gene, adeF, qacG, Mtub_rpsL_STR, vanY_gene_, vanW_gene, Mtub_murA_FOF, vanY_gene, vanH_gene, FosG, rsmA, qacJ, RbpA, vanW_gene, aadA6, vanY_gene, sul4, sul1, and InuF. The resistance genes mentioned above belong to the following categories of drug resistance mechanisms: antibiotic target replacement, antibiotic target protection, antibiotic inactivation, and antibiotic efflux. The resistomes that match the top 20 genes are Streptococcus agalactiae and Streptococcus anginosus; Enterococcus faecalis; Enterococcus faecium; Actinomyces viscosus and Bacillus cereus. Enterococcus faecium; Clostridium tetani; Streptococcus agalactiae and Streptococcus anginosus; Streptococcus agalactiae and Streptococcus anginosus; Acinetobacter baumannii, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium longum, Corynebacterium jeikeium, Corynebacterium urealyticum, Mycobacterium kansasii, Mycobacterium tuberculosis, Schaalia odontolytica, and Trueperella pyogenes; Mycobacterium avium and Mycobacterium tuberculosis; Aeromonas caviae, Enterobacter hormaechei, Vibrio cholerae, Vibrio metoecus, Vibrio parahaemolyticus, and Vibrio vulnificus; Pseudomonas aeruginosa and Pseudomonas fluorescens; Staphylococcus aureus and Staphylococcus equorum; M. avium, Achromobacter xylosoxidans, and Acinetobacter baumannii; Sphingobium yanoikuyae, Acinetobacter indicus, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, and Providencia stuartii. Unreported drug resistance genes and drug-resistant bacteria in Central China were identified in 2023. In the transmission path of drug resistance genes, the transmission path from aquaculture wastewater to human drinking water sources cannot be ignored. For the sake of human health and ecological balance, the treatment of aquaculture wastewater needs to be further strengthened, and the effective blocking of drug resistance gene transmission needs to be considered.

Livestock wastewater bioremediation through indigenous microalgae culturing as a circular bioeconomy approach as cattle feed

Growing human population demands the enhancement intensive livestock activities, which lead to severe environmental issues like water pollution. Cattle wastewater is rich in some inorganic pollutants, mainly nitrogen and phosphorous, which might constitute a risk to water bodies. Considering this scenario, microalgae's capacity to develop within manure wastewater is attracting interest, mainly for simultaneous wastewater bioremediation and biomass production. The aim of this work was evaluating the response of several microalgae strains to increasing percentages of unsterilized cattle farm wastewater. Moreover, this study also analyses the possibility of enhancing the development of indigenous native microalgal strains, to create a bioremediation system based on previously adapted species, which specific diversity was determined through taxonomic techniques. Two monospecific Chlorophyceae strains were used: Chlorella sp. and Coelastrella cogersae; and one Cyanobacteria strain: Arthrospira platensis. Experimental assays were conducted in 6 groups and triplicates with increasing percentages of Livestock wastewater (LW): control, 15, 25, 35, 50 and 70 %. All the strains tested showed that cattle wastewater represented a source of metabolic stress for microalgae development. Nevertheless, the autochthonous microalgal bloom showed better results in terms of tolerance to wastewater percentage and development under same conditions Laboratory scale results showed that microalgae could develop with optimum results in presence of 15 % of wastewater, reaching absorbance values close to 90 % of the achieved by control cultures. Moreover, indigenous microalgae cultures were scaled up to open type industrial systems (raceways) and influence of their growth on wastewater composition was evaluated. Results showed a severe reduction of the concentration of nitrates to 43.4 (mg·L−1) (20 % of initial measurements). Moreover, the obtained biomass showed a biochemical profile similar to traditional crops, in terms of proteins and carbohydrates (48 and 41 % respectively), suggesting that this biomass could be further valuated into cattle feed as a circular economy approach.