Treatment try of simulated agricultural surface runoff pollution by using a novel biomass concentrator reactor.

Increased agricultural surface runoff in rural watersheds is a leading cause of nonpoint source pollution. In this study, a new biomass concentrator reactor (BCR) is conducted to degrade simulated agricultural surface runoff for both start-up process and treatment process. The results show that both in the start-up phase and in the stable phase, BCR had a good degradation effect on simulated agricultural surface runoff. Within 13 days-15 days of completed start-up of BCR, degradation of COD can be considered to the first-order kinetics: lnCt=lnC0-0.1377t (R2 = 0.78). During the stabilization phase, the average removal rate of COD, NH4+-N, NO3--N, TN and TP from the effluents through the BCR membrane was 94.58%, 85.79%, 53.58%, 37.87%, and 60.62%, respectively, which was increased by 7.4%, 2.5%, 5.1%, 0.18% and 11.4%, respectively, compared to control experiment which the effluents without membrane. The pollutants degradation by BCR in stable phase show a partly relative model of Lawrence-McCarty equation, which the nitrogen and phosphorus degradation is vN=(4.1+S)/(2.53×S) (R2 = 0.69) and vP=(8.78+S)/(3.0×S) (R2 = 0.67), respectively. In the stable phase, the operation cost of BCR is about $0.08/(L•d). Future research on improved BCR maybe focus on the membrane pollution and cleaning, optimized operation conditions, new materials of membrane.

Characteristics of methane emissions in the Living Water Garden in Chengdu City from 2012 to 2017.

CH4 flux measured by a portable chamber using an infrared analyzer was compared with the flux by static chamber measurement for CW at 13 different sites from May 2012 to May 2017 in the Living Water Garden (LWG) in Chengdu, Sichuan Province, China, over 4 timescales (daily, monthly, seasonal, and annual). During the measurement period, a total of 1443 data were collected. CH4 fluxes were measured using the portable chamber method and the results showed that the annual mean and median CH4 flux values in the LWG were 17.4 mg m-2 h-1 and 6.2 mg m-2 h-1, respectively, ranging from - 19.7 to 98.0 mg m-2 h-1. Cumulative CH4 emissions for LWG ranged from - 0.17 to 0.86 kg m-2 year-1. Global warming potential (GWP, 25.7 kg CO2eq m-2 year-1) was at a high level, which means that the LWG was a source of CH4 emissions. Significant temporal variations on the 4 timescales were observed. And the asymmetry of measurement uncertainty of CH4 flux increases with the timescale. Although the total mean CH4 flux measured by the portable chamber method was 42.1% lower than that of the static chamber method, the temporal variation trends of CH4 flux were similar. The uncertainty of CH4 flux measured in portable chamber was more symmetrical than that in static chamber. These results suggest that the portable chamber method has considerable value as a long-term measurement method for CH4 flux temporal variations.

Whether the carbon emission from green roofs can be effectively mitigated by recycling waste building material as green roof substrate during five-year operation?

Green roof (GF) as an important role of urban ecosystem services is more and more focused on carbon sequestration for the mitigation of climate change, which there is still a gap of longer period of investigation on carbon sequestration on GF. This work aims to quantify the carbon sequestration on green roofs from 2012 to 2017 by measuring and calculating parameter on substrate organic carbon and plant organic carbon, when using waste building material substrate (WBMS) as GF substrate for the recycling of waste solid. Green roof group 2 (waste building material substrate (WBMS) as substrate) and green roof group 1 (local natural soil (LNS) as substrate), planting same three native plants (N. auriculata, L. spicata, and L. vicaryi), were both three substrate depth of 20 cm, 25 cm, and 30 cm, respectively. Results show that both innovative WBMS and LNS were a great capability of carbon sequestration and carbon storage on green roofs. Carbon storage of green roof group 1 and green roof group 2 was 65.6 kg C m-2 and 72.6 kg C m-2, respectively. Annual mean carbon sequestration of the WBMS was 1.8 times higher than LNS. The overall average carbon sequestration (12.8 kg C m-2 year-1) in green roof group 2 using WBMS was 1.1 times than corresponding in green roof group 1 (11.4 kg C m-2 year-1 using LNS). WBMS substrate and L. vicaryi could be considered as the most adaptable green roof configuration, which can be a recommendation to promote the carbon sequestration and the function of green roof for the better urban ecosystem services. Future work may focus on the GF carbon model, water interface, long-term monitoring, environmental impact, water quality and quantity, synthesized effect on GF ecosystem, low impact development (LID), management and simulation, and combination on intelligent urban system, based on LCA.

Influence of Plant Species on Microbial Activity and Denitrifier Population Development in Vegetated Denitrifying Wood-Chip Bioreactors.

The microbial characteristics of four vegetated and one unplanted wood-chip bioreactors treating greenhouse effluent were investigated in a continuous experiment operated for over 2.5 years. The bioreactors were designed to reduce nitrate concentrations via naturally induced microbial denitrification. The vegetation type and reactor depth were both found to be significant factors in defining the mixed microbial activity. However, a consistent correlation between the abundance of the denitrifying communities and reactor depth could not be found across all reactors. The media samples from the unit planted with Typha angustifolia displayed higher microbial activities compared with the other reactors. This plant's root-associated bacteria also demonstrated the greatest copies of the denitrifying genes nirK and nosZ. The most abundant denitrifier communities and those encoding the nosZ gene were found in the unplanted reactor, followed by the T. angustifolia unit. The T. angustifolia reactor demonstrated greater microbial activity and denitrification capacity at the depth of 20 cm, while the greatest denitrification capacity in the unplanted reactor was found at the depth of 60 cm. These findings indicated the importance of the T. angustifolia rhizosphere to support microbial community establishment and growth in the vicinity of the plant's roots, although those populations may eventually develop in an unplanted environment.

Interstitial water microbial communities as an indicator of microbial denitrifying capacity in wood-chip bioreactors.

The discharge from food production greenhouses (greenhouse effluent) contains high nutrient and salt concentrations, which, if directly released, can have adverse effects on the environment. Wood-chip bioreactors are increasingly popular passive water treatment systems favoured for their economical denitrification in treating agricultural field tile drainage. Microbial communities are central to denitrification; however little is known about the maturation of microbial communities in wood-chip bioreactors treating greenhouse effluents. In this study, multiple subsurface flow wood-chip bioreactors, each vegetated with a different plant species, together with an unplanted unit, received synthetic greenhouse effluent with elevated nitrate concentrations. The hybrid bioreactors were operated for over 2 years, during which time water samples were collected from the inlet, outlet and within the reactors. The increasing denitrification rate in the bioreactor planted with Typha angustifolia (narrowleaf cattail) correlated with increasing microbial activity and metabolic richness, measured by the carbon utilization patterns in Biolog® EcoPlates. Increased denitrifying gene (nirS) copies (determined by quantitative polymerase chain reaction, qPCR), and near-complete nitrate removal were observed in the T. angustifolia and unplanted reactors after 16 and 23 months of operation respectively. The findings suggested that an acclimation period of at least one year can be expected in unseeded bioreactors planted with T. angustifolia, while bioreactors without vegetation may require a longer time to maximize their denitrification capacity. These results are important for the design and operation of wood-chip bioreactors, which are expected to be more commonly applied in the future.

Intermittent micro-aeration control of methane emissions from an integrated vertical-flow constructed wetland during agricultural domestic wastewater treatment.

It is very important to control methane emissions to mitigate global warming. An intermittent micro-aeration control system was used to control methane emissions from an integrated vertical-flow constructed wetland (IVCW) to treat agricultural domestic wastewater pollution in this study. The optimized intermittent micro-aeration conditions were a 20-min aeration time and 340-min non-aeration time, 3.9 m3 h-1 aeration intensity, evenly distributed micro-aeration diffusers at the tank bottom, and an aeration period of every 6 h. Methane flux emission by intermittent micro-aeration was decreased by 60.7% under the optimized conditions. The average oxygen transfer efficiency was 26.73%. The control of CH4 emission from IVCWs was most strongly influenced by the intermittent micro-aeration diffuser distribution, followed by aeration intensity, aeration time, and water depth. Scaling up of IVCWs is feasible in rural areas by using intermittent micro-aeration control as a mitigation measure for methane gas emissions for climate change.

Anaerobic co-digestion of municipal organic wastes and pre-treatment to enhance biogas production from waste.

Co-digestion and pre-treatment have been recognized as effective, low-cost and commercially viable approaches to reduce anaerobic digestion process limitations and improve biogas yields. In our previous batch-scale study, fat, oil, and grease (FOG) was investigated as a suitable potential co-substrate, and thermo-chemical pre-treatment (TCPT) at pH = 10 and 55 °C improved CH4 production from FOG co-digestions. In this project, co-digestions with FOG were studied in bench-scale two-stage thermophilic semi-continuous flow co-digesters with suitable TCPT (pH = 10, 55 °C). Overall, a 25.14 ± 2.14 L/d (70.2 ± 1.4% CH4) biogas production was obtained, which was higher than in the two-stage system without pre-treatment. The results could provide valuable fundamental information to support full-scale investigations of anaerobic co-digestion of municipal organic wastes.

Anthropogenic impacts on a bedrock aquifer at the village scale.

This study focuses on assessing groundwater potability in a highly complex and heterogeneous fractured bedrock aquifer having variable overburden cover. Eight monitoring wells were installed in a privately serviced lakeside village, and groundwater was routinely sampled over a 2-year timeframe for concentration analysis of nitrate, fecal indicator bacteria, stable isotopes, and a total of 41 pharmaceutical compounds. While pollutant concentrations remained low throughout the study, the presence of fecal indicator bacteria and pharmaceuticals was noted at least once (but not always consistently) in most sampling intervals. An interpretation based on the integration of chemical, bacterial, and site characterization datasets suggests that: (1) the fracture network is complex and heterogeneous with limited vertical connectivity; (2) existing pathways are sufficient for the quick and widespread migration of surface contaminants to depth; (3) anthropogenic contaminants from both septic systems and agriculture are likely sourced in the surrounding uplands where overburden is thin; and (4) fecal contamination, as observed over the long term, is ubiquitous at the village scale. Groundwater quality is continually changing in this hydrogeologic environment and the determination of potability on the larger scale is not likely to be adequately captured with infrequent domestic well sampling (i.e., voluntary annual sampling by homeowners).

Effects of ultrasonic and thermo-chemical pre-treatments on methane production from fat, oil and grease (FOG) and synthetic kitchen waste (KW) in anaerobic co-digestion.

The effects of ultrasonic and thermo-chemical pre-treatments on the methane production potential of anaerobic co-digestion with synthetic kitchen waste (KW) or fat, oil and grease (FOG) were investigated. Non-linear regressions were fitted to accurately assess and compare the methane production from co-digestion under the various pre-treatment conditions and to achieve representative simulations and predictions. Ultrasonic pre-treatment was not found to improve methane production effectively from either FOG co-digestion or KW co-digestions. Thermo-chemical pre-treatment could increase methane production yields from both FOG and KW co-digestions. COD solubilization was found to effectively represent the effects of pre-treatment. A comprehensive evaluation indicated that the thermo-chemical pre-treatments of pH=10, 55°C and pH=8, 55°C provided the best conditions to increase methane production from FOG and KW co-digestions, respectively. The most effective enhancement of biogas production (288±0.85mLCH(4)/g TVS) was achieved from thermo-chemically pre-treated FOG co-digestion, which was 9.9±1.5% higher than FOG co-digestion without thermo-chemical pre-treatment.

Evaluating and modeling biogas production from municipal fat, oil, and grease and synthetic kitchen waste in anaerobic co-digestions.

The feasibility of using synthetic kitchen waste (KW) and fat, oil, and grease (FOG) as co-substrates in the anaerobic digestion of waste activated sludge (WAS) was investigated using two series of biochemical methane potential (BMP) tests. Ranges of ideal substrate to inoculum (S/I) ratio were determined for the FOG (0.25-0.75) and KW (0.80-1.26) as single substrates in the first experiment. The second experiment, which estimated the methane production performances of FOG and KW as co-substrates for WAS co-digestion, was conducted based on the optimal parameters selected from the results of the first experiment. Results indicated that co-digestions with FOG and KW enhanced methane production from 117±2.02 mL/gTVS (with only WAS) to 418±13.7 mL/gTVS and 324±4.11 mL/gTVS, respectively. FOG exhibited more biogas production than KW as co-substrate. Non-linear regression results showed that co-substrate addition shortened the lag phases of organic biodegradation from 81.8 (with only WAS) to 28.3 h with FOG and 3.90 h with KW.

Haemophilus somnus (Histophilus somni) in bighorn sheep.

Respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations. Haemophilus somnus (recently reclassified as Histophilus somni) is associated with respiratory disease in American bison, domestic sheep, and cattle. It is also harbored in their reproductive tracts and has been associated with reproductive failure in domestic sheep and cattle. Therefore, reproductive tract and lung samples from bighorn sheep were evaluated for the presence of this organism. Organisms identified as H. somnus were isolated from 6 of 62 vaginal but none of 12 preputial swab samples. Antigen specific to H. somnus was detected by immunohistochemical study in 4 of 12 formalin-fixed lung tissue samples of bighorn sheep that died with evidence of pneumonia. Notably, H. somnus was found in alveolar debris in areas of inflammation. The 6 vaginal isolates and 2 H. somnus isolates previously cultured from pneumonic lungs of bighorn sheep were compared with 3 representative isolates from domestic sheep and 2 from cattle. The profiles of major outer membrane proteins and antigens for all of the isolates were predominantly similar, although differences that may be associated with the host-parasite relationship and virulence were detected. The DNA restriction fragment length profiles of the bighorn-sheep isolates had similarities not shared with the other isolates, suggesting distinct phylogenetic lines. All of the isolates had similar antimicrobial profiles, but the isolates from the bighorn sheep produced less pigment than those from the domestic livestock, and growth of the former was not enhanced by CO2. Wildlife biologists and diagnosticians should be aware of the potential of these organisms to cause disease in bighorn sheep and of growth characteristics that may hinder laboratory detection.