Cover illustration
see: Conor Dennehy, Peadar G. Lawlor, Yan Jiang, Gillian E. Gardiner, Sihuang Xie, Long D Nghiem & Xinmin Zhan, 2017, 11(3): 11
Manure management is the primary source of greenhouse gas emissions from pig farming, which in turn accounts for 18% of the total global greenhouse gas emissions from the livestock sector. N2O and CH4 are emitted from individual pig manure management practices including manure storage, land application, solid/liquid separation, anaerobic digest
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Co-composted cattle manure and construction & demolition (C&D) waste. Studied two types of cattle manure, from typical vs. dried distillers’ grain with solubles (DDGS) diets. C&D waste reduces CH4 emission from cattle manure composting. Cattle manure composting emits lower CH4 than stockpiling. No difference in GHG emissions between types of cattle manure.
Manure management strategies should reflect current animal feeding practices and encourage recycling of organic waste to help protect our environment. This research investigated greenhouse gas (GHG) emissions during cattle manure stockpiling or composting with and without construction and demolition (C&D) waste. Manure was collected from cattle fed a typical finishing diet (CK manure) and from cattle on diets which included 30% dried distillers grains with solubles (DG manure). The CK and DG manures were co-composted with (4:1) C&D waste (treatments: CK_CD, DG_CD), composted alone (treatments: CK and DG) in 13 m3 bins or stockpiled without C&D waste (treatments: CK_ST and DG_ST) for 99 days. Manure type (CK vs. DG manure) had no effect on GHG emissions over the 99 day manure composting or stockpiling. Composting with C&D waste produced similar CO2 emissions, about double that from manure stockpiling (7.0 kgC·m−2). In contrast, CH4 emissions were reduced by the inclusion of C&D waste (64 gC·m−2 with C&D vs. 244 gC·m−2 without C&D) while the manure stockpile emitted the greatest amount of CH4 (464 gC·m−2). Additionally, only 0.48% of C was emitted in CH4 form with C&D waste, compared to 1.68% when composting without C&D waste and 7.00% when cattle manure was stockpiled. The N2O emissions (12.4 to 18.0 gN·m−2) were similar across all treatments. The lower CH4 emissions with C&D waste are beneficial in reducing overall GHG emissions from manure composting, while reducing the amount of material entering landfills.
The mass balance analysis of organic carbon were applied. The IASBR displays higher ratios of denitrificated organic carbon. The effects of anoxic stress duration on nitrification activity were evaluated. The anoxia time of 40–80 min achieves more stable nitritation. The intermittent aeration strategy improved the removal of fluorescent substance.
An intermittently aerated sequencing batch reactor (IASBR) and a traditional sequencing batch reactor (SBR) were parallelly constructed to treat digested piggery wastewater, which was in high NH4+-N concentration but in a low COD/TN ratio. Their pollutant removal performance was compared under COD/TN ratios of 1.6–3.4 d and hydraulic retention times of 5–3 d. The results showed that the IASBR removed TN, NH4+-N and TOC more efficiently than the SBR. The average removal rates of TN, NH4+-N and TOC were 83.1%, 96.5%, and 89.0%, respectively, in the IASBR, significantly higher than the corresponding values of 74.8%, 82.0%, and 86.2% in the SBR. Mass balance of organic carbon revealed that the higher TN removal in the IASBR might be attributed to its efficient utilization of the organic carbon for denitrification, since that 48.7%–52.2% of COD was used for denitrification in the IASBR, higher than the corresponding proportion of 43.1%–47.4% in the SBR. A pre-anoxic process in the IASBR would enhance the ammonium oxidation while restrict the nitrite oxidation. Anoxic duration of 40–80 min should be beneficial for achieving stable nitritation.
Global warming potential of milk powder production in Ireland is assessed. The GWP of 1 kg milk powder is 9.731 kg CO2eq. The standard deviation for the GWP of 1 kg milk powder is 2.26 kg CO2eq. The most significant contributor to GWP is raw milk production at 84%. Processing of raw milk into milk powder accounts for 14% of the total GWP.
Climate change is an ever growing issue and a major concern worldwide. Both producers and processors need to address the issue now by reducing their carbon footprint. Additionally, if Ireland is to meet their climate and energy targets, as outlined in Food Harvest 2020, which outlines a range of objectives for the Irish agricultural sector, the efficient use of resources and fuels within the industry will need to be increased. In Ireland, agriculture accounts for 29.2% of the total greenhouse gas emissions (58.5 million tonnes CO2eq). Therefore, in this paper, a single agri-food product, milk powder, is examined in order to estimate the global warming potential (GWP) associated with its manufacture using life cycle assessment. A cradle-to-processing factory gate analysis, which includes raw milk production, raw milk transportation to the processing factory, its processing into each product and product packaging, is assessed in this study using data collected circa 2013. The factories surveyed processed approximately 24% of the total raw milk processed in the Republic of Ireland in 2013, which was 5.83 billion liters. The average total GWP associated with the manufacture of milk powder is 9.731 kg CO2eq·kg−1 milk powder, which has a standard deviation of 2.26 kg CO2eq·kg−1 milk powder, for the life cycle stages analyzed in this study. The most significant contributor to GWP is raw milk production (84%), followed by dairy processing (14%), with the remainder of the life cycle stages contributing approximately 2%.
Emissions from manure management are the primary source of GHGs in pig farming. The effect of pig manure management practises on GHG emissions was assessed. Recommendations made to standardise units and account for indirect N2O emissions. AD and compositing should be employed to mitigate GHG emissions in PGM management.
Manure management is the primary source of greenhouse gas (GHG) emissions from pig farming, which in turn accounts for 18% of the total global GHG emissions from the livestock industry. In this review, GHG emissions (N2O and CH4 emissions in particular) from individual pig manure (PGM) management practices (European practises in particular) are systematically analyzed and discussed. These manure management practices include manure storage, land application, solid/liquid separation, anaerobic digestion, composting and aerobic wastewater treatment. The potential reduction in net GHG emissions by changing and optimising these techniques is assessed. This review also identifies key research gaps in the literature including the effect of straw covering of liquid PGM storages, the effect of solid/liquid separation, and the effect of dry anaerobic digestion on net GHG emissions from PGM management. In addition to identifying these research gaps, several recommendations including the need to standardize units used to report GHG emissions, to account for indirect N2O emissions, and to include a broader research scope by conducting detailed life cycle assessment are also discussed. Overall, anaerobic digestion and compositing to liquid and solid fractions are best PGM management practices with respect to their high GHG mitigation potential.
CH4 and N2O emissions from pig wastewater treatment facilities were measured. N2O emission rate was affected by environmental conditions, location, management. Emission factors: CH4,0.91% (kgCH4·kgVS−1) and N2O, 2.87% (kgN2O-N·kgN−1).
The activated sludge process to remove nitrogen and biochemical oxygen demand (BOD) is reportedly cost-effective for swine wastewater treatment, and it use has thus increased in pig farming. Nitrous oxide (N2O) is generated on farms as an intermediate product in nitrification and denitrification, and methane (CH4) is also generated from organic degradation under anaerobic conditions by microorganisms in manure or wastewater. This study was carried out at five activated sludge treatment facilities across Japan between August 2014 and January 2015. Measurements were conducted over several weeks at wastewater purification facilities for swine farms: two in Chiba prefecture (East Japan), two in Okayama prefecture (West Japan), and one in Saga (Southern Japan). Taking several environmental fluctuations into account, we collected measurement data continuously day and night, during both high-temperature and low-temperature periods. The results indicated that CH4 and N2O emission factors were 0.91% (kgCH4· kg volatile solids−1) and 2.87% (g N2O-N· kg total N−1), respectively. Ammonia emissions were negligible in all of the measurements from the wastewater facilities. The N2O emission factor calculated under this experiment was low compared to our previous finding (5.0%; g N2O-N· kg N−1) in a laboratory experiment. In contrast, the CH4 emission factor calculated herein was rather high compared to the laboratory measurements. There was great variation in daily GHG emission factors measured in the actual wastewater treatment facilities. In particular, the N2O emission rate was affected by several environmental conditions at each facility location, as well as by the management of the wastewater treatment.
Hydrothermal carbonization treatment eliminates pathogens and microbial DNA. Hydrothermal carbonization treatment worked at both 150°C and 200°C. Hydrothermal carbonization treatment worked in both bovine bone and tissue. 30 minute treatment was sufficient for pathogen kill and complete DNA degradation.
Hydrothermal carbonization (HTC), utilizing high temperature and pressure, has the potential to treat agricultural waste via inactivating pathogens, antibiotic resistance genes (ARG), and contaminants of emerging concern (CEC) in a environmental and economical manner. Livestock mortality is one facet of agricultural waste that can pose a threat to the surrounding environment. While several methods are utilized to treat livestock mortality, there remains a paucity of data on the elimination of microbially-derived DNA in these treatment practices. This DNA, most notably ARGs, if it survives treatment can be reintroduced in agricultural environments where it could potentially be passed to pathogens, posing a risk to animal and human populations. HTC treatments have been successfully utilized for the treatment of CECs, however very little is understood on how ARGs survive HTC treatment. This study aims to fill this knowledge gap by examining the survivability of microbially-derived DNA in the HTC treatment of livestock mortality. We examined three treatment temperatures (100°C, 150°C, and 200°C) at autogenic pressures at three treatment times (30, 60, and 240 min). We examined the amplification of a plasmid-borne reporter gene carried byEscherichia coli DH10B introduced to both beef bone and tissue. Results indicate that while all three temperatures, at all treatment times, were suitable for complete pathogen kill, only temperatures of 150°C and 200°C were sufficient for eliminating microbial DNA. These results serve as the basis for future potential HTC treatment recommendations for livestock mortality when considering the elimination of pathogens and ARGs.
IASBRs achieved a higher level of TN and NH4+-N removals than the SBR. IASBRs had higher abundance of denitrification–related bacteria than the SBR. The denitrifiers abundance was correlated with the TN removal rate. The NH4+–N removal rate might relate to the AOB activity.
A traditional sequencing batch reactor (SBR) and two intermittently aerated sequencing batch reactors (IASBRs) were parallelly operated for treating digested piggery wastewater. Their microbial communities were analyzed, and the nitrogen removal performance was compared during the long–term run. IASBRs demonstrated higher removal rates of total nitrogen (TN) and ammonium nitrogen (NH4+-N) than the SBR, and also demonstrated higher resistance against TN shock load. It was found that the more switch times between aerobic/anoxic in an IASBR, the higher the removal rates of TN and NH4+–N. All the reactors were predominated by Thauera, Nitrosomonas and Nitrobacter, which were considered to be species of denitrifiers, ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB), respectively. However, the abundance and diversity was of great difference. Compared with SBR, IASBRs achieved higher abundance of denitrification–related bacteria. IASBR 1 with four aerobic/anoxic switch times was detected with 25.63% of Thauera, higher than that in IASBR 2 with two aerobic/anoxic switch times (11.57% of Thauera), and much higher than that in the SBR (only 6.19% of Thauera). IASBR 2 had the highest percentage of AOB, while IASBR 1 had the lowest percentage. The denitrifiers abundance was significantly positive correlated with the TN removal rate. However, the NH4+–N removal rate showed no significant correlation with the AOB abundance, but might relate to the AOB activity which was influenced by the average free ammonium (FA) concentration. Nitrobacter was the only NOB genus detectable in all reactors, and were less than 0.03%.
Topical application of microbial-mineral manure additive was investigated. Mineral sorbent treatment reduced VOCs emissions by 31% to 83%. Bio-additive treatment reduced VOCs emissions 9% to 96%. There were no significant differences between applied treatments. Aroma profile of the poultry manure has been determined.
Poultry production systems are associated with emissions of odorous volatile organic compounds (VOCs), ammonia (NH3), hydrogen sulfide (H2S), greenhouse gases, and particulate matter. Development of mitigation technologies for these emissions is important. Previous laboratory-scale research on microbial-mineral treatment has shown to be effective for mitigation of NH3, H2S and amines emissions from poultry manure. The aim of this research was to assess the effectiveness of surface application of a microbial-mineral treatment for other important odorants, i.e., phenolics and sulfur-containing VOCs. Microbial-mineral litter additive consisting of 20% (w/w) of bacteria powder (six strains of heterotrophic bacteria) and 80% of mineral carrier (perlite-bentonite) was used at a dose of 500 g?m-2 (per ~31 kg of manure). Samples of air were collected in two series, 4 and 7 days after application of additives. An odor profile of the poultry manure was determined using simultaneous chemical and sensory analysis. Reduction levels of VOCs determined on Day 4 was between 31% and 83% for mineral adsorbent treatment and in the range of 9% and 96% for microbial-mineral additive, depending on the analyzed compound. Reduction levels on Day 7 were considerably lower than on Day 4, suggesting that the odorous VOCs treatment efficacy is relatively short. There was no significant difference between treatments consisting of microbial-mineral additive and mineral carrier alone.
A cold-adapt laccase excreted by a fungi from rotten tomato was characterized. The laccase can effectively transform triclosan to form polymerized products. The reaction rate is first order to the concentrations of both laccase and triclosan. The reaction was inhibited by humic acid.
This work investigated the transformation of triclosan (TCS) by laccase produced by a pathogen isolated from rotten tomato. The pathogen was characterized asBotrytis sp. FQ, belonging to subphylum Deuteromycotina. The laccase exhibited cold-adaptation with relatively high activity at 20°C. The laccase could effectively transform TCS. Approximately 62% TCS could be removed at dose of 1.0 unit·mL−1 in 120 min. The reaction rate appeared to be pseudo-first-order to the concentration of the substrate, suggesting the laccase activity remained stable during the reaction. Transformation products of TCS were analyzed by mass spectrometry and it was revealed that TCS dimers were formed via radical coupling pathways. During this process, laccase catalyzed oxidation of TCS to form a radical intermediate is the rate limiting step. However, this step can be reversed by humic acid. Overall, the laccase showed great potential in the treatment of phenolic contaminants. Since laccase is widely presented in natural environment, this study also revealed an important pathway involved in the transformation of phenolic contaminants in the environment.
Pyrolysis altered the speciation and lability of Cu/Zn in animal manure. The predominant species of Cu in two kinds of biochars differed with temperatures. Temperatures didn’t change the predominant species of Zn in manures and biochars . The bioaccessibility of Cu/Zn in biochars decreased with pyrolysis temperatures. The leaching of Cu/Zn with SPLP decreased with pyrolysis temperatures.
Biochars derived from animal manures may accumulate potentially toxic metals and cause a potential risk to ecosystem. The synchrotron-based X-ray spectroscopy, sequential fractionation schemes, bioaccessibility extraction and leaching procedure were performed on poultry and swine manure-derived biochars (denoted PB and SB, respectively) to evaluate the variance of speciation and activity of Cu and Zn as affected by the feedstock and pyrolysis temperature. The results showed that Cu speciation was dependent on the feedstock with Cu-citrate-like in swine manure and species resembling Cu-glutathione and CuO in poultry manure. Pyrolyzed products, however, had similar Cu speciation mainly with species resembling Cu-citrate, CuO and CuS/Cu2S. Organic bound Zn and Zn3(PO4)2-like species were dominant in both feedstock and biochars. Both Cu and Zn leaching with synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP) decreased greatly with the rise of pyrolysis temperature, which were consistent with the sequential extraction results that pyrolysis converted Cu and Zn into less labile phases such as organic/sulfide and residual fractions. The potential bioaccessibility of Zn decreased for both the PB and SB, closely depending on the content of non-residual Zn. The bioaccessibility of Cu, however, increased for the SB prepared at 300°C–700°C, probably due to the increased proportion of CuO. Concerning the results of sequential fractionation schemes, bioaccessibility extraction and leaching procedure, pyrolysis at 500°C was suggested as means of reducing Cu/Zn lability and poultry manure was more suitable for pyrolysis treatment.
Reducing HRT to 10.5 days caused shifts in acidogenic population & VFA accumulation. VFA-oxidizing bacteria were key in process stability when HRT was 10.5 days. Reducing HRT to 10.5 days reduced substrate utilization. Pathogen removal was not achieved when HRT was<21 days.
This study assessed the effects of reducing hydraulic retention times (HRTs) from 21 days to 10.5 days when anaerobically co-digesting pig manure and food waste. Continuously stirred tank reactors of 3.75 L working volume were operated in triplicate at 42°C. Digester HRT was progressively decreased from 21 to 15 days to 10.5 days, with an associated increase in organic loading rate (OLR) from 3.1 kg volatile solids (VS)·m−3·day−1 to 5.1 kg VS·m−3·day−1 to 7.25 kg VS·m−3·day−1. Reducing HRT from 21 days to 15 days caused a decrease in specific methane yields and VS removal rates. Operation at a HRT of 10.5 days initially resulted in the accumulation of isobutyric acid in each reactor. High throughput 16S rRNA gene sequencing revealed that this increase coincided with a shift in acidogenic bacterial populations, which most likely resulted in the increased isobutyric acid concentrations. This may in turn have caused the increase in relative abundance of Clocamonaceae bacteria, which syntrophically degrade non-acetate volatile fatty acids (VFAs) into H2 and CO2. This, along with the increase in abundance of other syntrophic VFA oxidizers, such as Spiorchatetes, suggests that VFA oxidation plays a role in digester operation at low HRTs. Reducing the HRT to below 21 days compromised the ability of the anaerobic digestion system to reduce enteric indicator organism counts below regulatory limits.
Danio rerio behavior responses could reflect environmental stress of DM pollution. Sodium percarbonate is a good choice in situ remediation of the DM pollution. In situ remediation of DM based on online mixing and monitoring system is effective.
In this research, the toxic effects of deltamethrin (DM) on the behavior responses of Zebra fish (Danio rerio) in the characteristic of behavior strength were investigated followed by an assessment of an in situ remediation of the DM pollution using sodium percarbonate. Behavior strength ofDanio rerio was approximately 0.83 in the control group and was slightly higher than 0.83 in the sublethal treatment (0.1 TU (toxic unit)), which suggested that sublethal DM exposure could induce a stimulation effect in 48 h of exposure. In lower DM concentration treatments (0.5 and 1.0 TU), behavior strength could be inhibited significantly. Behavior responses ofDanio rerio showed a gradually increased tendency when they were exposed to higher concentration of DM, and the declining amplitudes of behavior strength changed with the increase of DM concentrations. These results suggested that DM had evident acute toxicity effects on the behavior responses ofDanio rerio with a good dose-effect relationship. The in situ remediation of the DM pollution using sodium percarbonate showed that the toxic effect of DM on behavior responses ofDanio rerio could be eliminated even in the highest concentration of DM (5.0 TU). Meanwhile, the behavior response of Danio rerio in the treatment of sodium percarbonate was the same as in the control, which indicated that sodium percarbonate had no evident toxic effects on the behavior ofDanio rerio in the current concentration. This study suggested that adding sodium percarbonate in situ might be a good way to eliminate the DM toxic effects.
A column study showed woody media reduced liquid waste volume compared to gravel. Mixtures of torrefied wood and biochar improved nutrient concentration reductions. Total N removal was improved by retaining the liquid in the wood media for 48 h. Unmodified Mixed Hardwood may be most cost effective HUA media.
Overwintering cattle on pastures in many areas can damage the pasture and lead to impaired water quality. During these times, use of a woodchip heavy-use area (HUA) presents advantages such as a soft, supportive, and dry foot surface for animals and protection of the pasture and pasture soils. However, woodchip HUAs can also be a centralized source of high nutrient loads due to their drainage outflows. A column study was conducted to assess the nutrient load reduction potential of: 1) six types of wood media (including torrefied wood media and biochar) that could be used in a woodchip HUA versus a gravel control, and 2) providing a 48 h retention time within the wood media to enhance nitrogen removal through denitrification. The woody media provided significant liquid waste volume reduction compared to the gravel in simulated events (53%–61% vs. 39% reductions, respectively), and there may be additional liquid storage capacity in the woodchips not utilized during these rapid events. Substantial total nitrogen removal by the wood treatments (mean removal efficiencies>50%) was observed across the simulated events, although nitrate leaching also occurred. Nitrate removal was enhanced during the 48 h retention test which showed removal was governed by availability of labile carbon (i.e., fresh woodchips exhibited>70% nitrate removal). The retention test also indicated biochar mixtures provided some of the best total phosphorus removal, but the greatest benefits across all parameters was provided by the Mixed Hardwood treatment.
Fall/Spring GHG emissions from a corn field & swine manure application were measured. Flux chamber method was used for farm-scale measurements. Four flux estimation models were evaluated for GHG emissions. GHG flux estimates that were not significantly (p<0.05) different between models. Spring reapplication of swine manure resulted in higher GHGs emissions.
Greenhouse gas emissions (GHGs) from swine production systems are relatively well researched with the exception of emissions from land application of manure. GHGs inventories are needed for process-based modeling and science-based regulations. Thus, the objective of this observational study was to measure GHG fluxes from land application of swine manure on a typical corn field. Assessment of GHG emissions from deep injected land-applied swine manure, fall and reapplication in the spring, on a typical US Midwestern corn-on-corn farm was completed. Static chambers were used for flux measurement along with gas analysis on a GC-FID-ECD. Measured gas concentrations were used to estimate GHGs flux using four different models: linear regression, nonlinear regression, first order linear regression and the revised Hutchinson and Mosier (HMR) model, respectively for comparisons. Cumulative flux estimates after manure application of 5.85 × 105 g·ha-1 (1 ha= 0.01 km2) of CO2, 6.60 × 101 g·ha-1 of CH4, and 3.48 × 103 g·ha-1 N2O for the fall trial and 3.11 × 106 g·ha-1 of CO2, 2.95 × 103 g·ha-1 of CH4, and 1.47 × 104 g·ha-1 N2O after the spring reapplication trial were observed. The N2O net cumulative flux represents 0.595% of nitrogen applied in swine manure for the fall trial.
