Sorption behavior of tetracyclines on suspended organic matters originating from swine wastewater

Tetracyclines(TCs) discharged from livestock wastewater have aroused public concerns due to their pharmacological threats to ecosystems and human health. As an important medium in the wastewater, suspended organic matters(SOMs) play vital roles in antibiotics transport and degradation. However, limited information has been reported in the relevant literature. This study investigated TCs sorption behavior on SOM, withdrawn from swine wastewater. High TCs sorption capacities were detected, with the maximum values ranging from 0.337 to 0.679 mg/g. Increasing p H and temperature led to the decline of sorption capacity. Results from three-dimensional excitation–emission matrix fluorescence spectroscopy and Fourier transform infrared spectrometry revealed that amide and carboxyl groups were the main functional groups for TCs adsorption. The interactions between SOM and TCs were clarified as predominated by hydrogen-bonding and cation-exchange in acid conditions, and electrostatic repulsion in neutral or alkaline conditions. Adsorption kinetics modeling was conducted, and a satisfactory fitting was achieved with the Freundlich equation. These results indicated that the adsorption process was a rather complex process, involving a combination of cation-exchange and hydrogen-bonding. The results will provide a better understanding of the capability of SOM for TCs transport and abatement in the wastewater treatment process.     

Understanding gaseous reduction in swine manure resulting from nanoparticle treatments under anaerobic storage conditions

Manure is an impending source of carbon(C), sulfur(S) and water(H_2 O). Consequently,microbial populations utilize these constituents to produce methane(CH4), carbon dioxide(CO_2), greenhouse gases(GHGs), and hydrogen sulfide(H_2 S). Application of nanoparticles(NPs) to stored manure is an emerging GHG mitigation technique. In this study, two NPs: nano zinc oxide(nZnO) and nano silver(nAg) were tested in swine manure stored under anaerobic conditions to determine their effectiveness in mitigating gaseous emissions and total gas production. The biological sources of gas production, i.e., microbial populations were characterized via Quantitative Polymerase Chain Reaction(qPCR) analysis. Additionally, pH, redox, and VFAs were determined using standard methods. Each treatment of the experiment was replicated three times and NPs were applied at a dose of 3 g/L of manure. Also, headspace gas from all treatment replicates were analyzed for CH_4 and CO_2 gas concentrations using an SRI-8610 Gas Chromatograph and H_2 S concentrations were measured using a Jerome 631 X meter. Nanoparticles tested in this study reduced the cumulative gas volume by 16%–79% compared to the control. Among the NPs tested, only nZnO consistently reduced GHG concentrations by 37%–97%. Reductions in H_2 S concentrations ranged from 87% to97%. Gaseous reductions were likely due to decreases in the activity and numbers of specific gas producing methanogenic archaea and sulfate reducing bacterial(SRB)species.     

Nitrogen turnover on organic and conventional mixed farms

Separate focus on crop fertilization or feeding practices inadequately describes nitrogen (N) loss from mixed dairy farms because of (1) interaction between animal and crop production and between the production system and the manager, and (2) uncertainties of herd N production and crop N utilization. Therefore a systems approach was used to study N turnover and N efficiency on 16 conventional and 14 organic private Danish farms with mixed animal (dairy) and crop production. There were significant differences in N surplus at the farm level (242 kg. N/ha. vs. 124 kg. N/ha. on conventional and organic dairy farms respectively) with a correlation between stocking rate and N surplus. N efficiency was calculated as the output of N in animal products divided by the net N import in fodder, manure and fertilizer. N turnover in herd and individual crops calculated on selected farms showed differences in organic and conventional crop N utilization. This is explained via a discussion of the rationality behind the current way of planning the optimum fertilizer application in conventional agriculture. The concept of marginal N efficiency is insufficient for correcting problems of N loss from dairy farms. Substantial reductions in N loss from conventional mixed dairy farms is probably unlikely without lower production intensity. The concept of mean farm unit N efficiency might be a way to describe the relation between production and N loss to facilitate regulation. This concept is linked to differing goals of agricultural development—i.e. intensification and separation vs. extensification and integration. It is discussed how studies in private farms—using organic farms as selected critical cases—can demonstrate possibilities for balancing production and environmental concern.     

Who should wear mask against airborne infections? Altering the contact network for controlling the spread of contagious diseases

There are several ways of controlling the propagation of a contagious disease. For instance, to reduce the spreading of an airborne infection, individuals can be encouraged to remain in their homes and/or to wear face masks outside their domiciles. However, when a limited amount of masks is available, who should use them: the susceptible subjects, the infective persons or both populations? Here we employ susceptible-infective-recovered (SIR) models described in terms of ordinary differential equations and probabilistic cellular automata in order to investigate how the deletion of links in the random complex network representing the social contacts among individuals affects the dynamics of a contagious disease. The inspiration for this study comes from recent discussions about the impact of measures usually recommended by health public organizations for preventing the propagation of the swine influenza A (H1N1) virus. Our answer to this question can be valid for other eco-epidemiological systems.     

Selected dark sides of biomass-derived biochars as environmental amendments

With the rapid increase in the application of biochars as amendments, studies are needed to clarify the possible environmental risks derived from biochars to use safely the biomass resources. This work reported selected dark sides of maize straw-and swine manurederived biochars pyrolyzed at 300 and 500°C. During the pyrolysis processes, total heavy metals in the biochars were enriched greatly accompanying with considerable emission of the heavy metals into atmosphere and the trends became increasingly obvious with pyrolysis temperature. Meanwhile, the biochars showed distinctly decreased available heavy metals compared with raw feedstocks, which could be mainly attributed to the sorption by the inorganics in the biochars. The water-and acid-washing treatments significantly increased the releasing risks of heavy metals from biochars into the environments. Electron paramagnetic resonance analysis indicated that persistent free radicals, emerged strongly in the biochars as a function of the aromatization of biomass feedstocks, were free from the influence of water-, acid-, or organic-washing of the biochars and could remain stable even after aged in soils for 30 days. Dissolved biochars, highly produced during pyrolysis processes, showed distinct properties including lower molecular weight distribution while higher aromaticity compared with soil dissolved organic carbon.The results of this study provide important perspectives on the safe usage of biochars as agricultural/environmental amendments.     

Adsorption behavior of sulfamethazine in an activated sludge process treating swine wastewater

Swine wastewater is an important pollution source of antibiotics entering the aquatic environment. In this work,the adsorption behavior of sulfamethazine(SMN),a commonlyused sulfonamide antibiotic,on activated sludge from a sequencing batch reactor treating swine wastewater was investigated. The results show that the adsorption of SMN on activated sludge was an initially rapid process and reached equilibrium after 6 hr. The removal efficiency of SMN from the water phase increased with an increasing concentration of mixed liquor suspended solids,while the adsorbed concentration of SMN decreased. Solution pH influenced both the speciation of SMN and the surface properties of activated sludge,thus significantly impacting the adsorption process. A linear partition model could give a good fit for the equilibrium concentrations of SMN at the test temperatures(i.e.,10,20 and 30°C). The partition coefficient(Kd) was determined to be 100.5 L/kg at 20°C,indicating a quite high adsorption capacity for SMN. Thermodynamic analysis revealed that SMN adsorption on activated sludge was an exothermic process. This study could help to clarify the fate and behavior of sulfonamide antibiotics in the activated sludge process and assess consequent environmental risks arising from sludge disposal as well.     

我国集约化畜禽养殖场污染治理障碍分析及对策

随着我国集约化畜禽养殖场的快速发展，行业污染危害日益严重，对自然环境和居民健康威胁很大。由于技术经济原因，只有综合利用、农牧一体的方法才能根本解决养殖场污染问题，但这种方式在我国存在着诸多推广障碍：环境标准和监管体系有缺陷、资金和技术门槛较高、副产品没有获得应有的市场回报等。建议采取以下措施促进综合利用：提高养殖场的排污标准和排污费征收标准，按照工业污染治理的办法进行养殖场环境监管，对这类污染在重点地区开展专项整治，从税收、土地价格、贷款等方面扶持综合利用。     

上海市郊区养殖场周边环境中砷含量特征

在上海市郊区选取5个大型养殖场,分别采集地表水、饲料、土壤及蔬菜样品,对其进行总砷及无机砷含量调查,以了解目前上海市郊区养殖场砷含量水平特征,以及有机胂饲料添加剂的使用情况.结果表明,水样中总砷含量介于0.00~23.00μg·L-1之间,低于国家规定的地表水环境质量一级标准(50μg·L-1);饲料中总砷含量在0.40~12.13 mg·kg-1之间,其中无机砷占总砷的10.0%~80.0%;抽查饲料样品中总砷含量范围为0.16~21.39 mg·kg-1,无机砷含量在0.003~10.67mg·kg-1之间,其中超过饲料中砷的限量标准的占16.7%;土壤中总砷含量介于8.08~18.50 mg·kg-1,22.2%的土壤样品中总砷含量超过土壤环境质量一级标准,土壤中无机砷占总砷44.2%~78.9%;蔬菜中总砷含量在0.003~0.093 mg·kg-1之间,均低于国家规定的限量标准0.50 mg·kg-1;同种蔬菜不同部位砷含量存在一定差异:根部含砷量要高于地上部分,蔬菜中总砷富集系数与总砷含量呈明显的正相关,与根际土壤中砷含量呈一定的负相关.     

Residual veterinary antibiotics in swine manure from concentrated animal feeding operations in Shandong Province, China

The scientific interest in the occurrence and fate of antibiotics in animal husbandry has increased during the past decades because of the emergence and development of antimicrobial resistance in pathogenic bacteria. This study developed a method for simultaneous detection of five sulfonamides, three tetracyclines and one macrolide in swine manure with stable recoveries (73.0-110.6%) and high sensitivity (limit of quantification <90 μg kg⁻¹). Thereafter, a total of 126 swine manure samples, collected from 21 concentrated animal feeding operations (CAFOs) in Shandong Province of China during summer and winter, were analyzed. The potential influences of different sampling seasons, swine types and food sources on residual antibiotic concentrations were examined in detail. The maximum concentration of residual antibiotic could reach up to 764.4 mg kg⁻¹ (chlortetracycline), and the detection frequencies were 84.9-96.8% for tetracyclines, 0.8-51.6% for sulfonamides and 4.8% for macrolide. These data reveal that antibiotics were extensively used in CAFOs in this district and the manure may act as a non-specific source of antibiotic residue in farmlands and aquatic environments.     

Occurrence and distribution of pharmaceuticals in wastewater from households, livestock farms, hospitals and pharmaceutical manufactures

Twenty-four pharmaceuticals were measured in wastewater from 12 municipal wastewater treatment plants (M-WWTPs), four livestock WWTPs (L-WWTPs), four hospital WWTPs (H-WWTPs) and four pharmaceutical manufacture WWTPs (P-WWTPs). The total concentration of pharmaceuticals in the influent samples was highest in the L-WWTPs followed by the P-WWTPs, H-WWTPs and M-WWTPs. The effluents had different patterns of pharmaceuticals than their corresponding influents because of the different fate of each compound in the WWTPs. Non-steroidal anti-inflammatory drugs (NSAIDs) were the most dominant in the influents from the M-WWTPs and P-WWTPs, while antibiotics were dominantly detected in the L-WWTP. In the H-WWTP influents, NSAIDs, caffeine and carbamazepine were dominant. In the P-WWTPs, the distribution of pharmaceuticals in the effluents varied with sampling sites and periods. The M-WWTP influents had the highest daily loads, while the effluents showed somewhat similar levels in all source types.