The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic was... more The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25-75 mL min −1 , although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.
This report provides a critical review of available evidence as to how effectively the various ca... more This report provides a critical review of available evidence as to how effectively the various categories and configurations of biofilter reduce bioaerosol and odour emissions from composting facilities.
Suppression of rice methane production and emission by low dose sulfate application
Large individual applications of SO 4 2- (10 2 -10 3 kg SO 4 2- -S/ha) are known to suppress meth... more Large individual applications of SO 4 2- (10 2 -10 3 kg SO 4 2- -S/ha) are known to suppress methane emissions from rice paddies by up to ~70%. The application of large quantities of SO 4 2- amendments to rice paddies has therefore been proposed as a greenhouse gas mitigation strategy. In a similar system, natural peatlands, research has established that very low rates of SO 4 2- deposition (~25 kg SO 4 2- -S/ha/yr as small weekly pulses), similar to those of regions experiencing acid rain pollution, suppress methane emissions by as much as 30-40%. It is thought that this is due to stimulation of sulfate-reducing microbial populations that out-compete methane producers for substrates. Given that acid rain S pollution is forecast to increase in Asia, the major rice growing region, we sought to establish the potential for acid rain to suppress CH 4 emission from rice agro-ecosystems by experimentally simulating acid rain inputs of S deposition to rice mesocosms in the laboratory. We u...
Safety in Composting Halls: Managing the risks from Carbon Monoxide
The importance of fitting the correct sensors for carbon monoxide monitoring in enclosed composti... more The importance of fitting the correct sensors for carbon monoxide monitoring in enclosed composting facilities has been highlighted by recent research conducted by the Open University, in collaboration with Amey Ltd. The research was commissioned due to concern about the frequency of alarm activations from carbon monoxide personal safety monitors within the composting facility of an MBT (Mechanical Biological Treatment) plant. Further investigation confirmed the presence of carbon monoxide in the compost hall, though at levels below the 30 ppm alarm threshold. However, nonhazardous levels of hydrogen were also present and caused interference to gas safety monitors, leading to false alarms for high carbon monoxide.
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic was... more The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25-75 mL min −1 , although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic was... more The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25-75 mL min −1 , although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.
Static, dynamic and inoculum augmented respiration based test assessment for determining in-vessel compost stability
Waste Management, 2015
The purpose of this work was to evaluate compost (and related industry) stability tests given rec... more The purpose of this work was to evaluate compost (and related industry) stability tests given recent large-scale changes to feedstock, processing techniques and compost market requirements. Five stability tests (ORG0020, DR4, Dewar self-heating, oxygen update rate (OUR) and static respiration) were evaluated on composts from ten in-vessel composting sites. Spearman rank correlation coefficients were strong for the ORG0020, OUR and DR4 (both CO2 and O2 measurement), however, OUR results required data extrapolation for highly active compost samples. By comparison the Dewar self-heating and static respiration tests had weaker correlations, in part the result of under reporting highly active, low pH samples. The findings suggest that despite differences in pre-incubation period both dynamic respiration tests (ORG0020 and DR4) are best suited to deal with the wide range of compost stabilities found.
A large-scale, outdoor vermicomposting system was monitored for 80 weeks. Earthworm populations w... more A large-scale, outdoor vermicomposting system was monitored for 80 weeks. Earthworm populations were recorded for 60 weeks in unheated beds operating at ambient temperatures (34 weeks at 6.3 ± 2.3°C) and in heated beds controlled at 13.7 ± 0.8°C for 34 weeks. Both blocks of beds were at ambient temperatures for the remaining 26 weeks. Earthworm biomass and the numbers of hatchlings and cocoons produced for the heated beds were found to be significantly greater than for the unheated beds. Nitrous oxide fluxes in winter (week 60) were 3.2 ± 0.3 mg m -2 h -1 (unheated beds), 1.8 ± 0.3 mg m -2 h -1 (heated beds), and these were significantly different to the control beds (0.1 ± 0.0 mg m -2 h -1 ). Emissions during summer (week 80) were 20.1 ± 3.0 mg m -2 h -1 (unheated beds), 21.3 ± 2.8 mg m -2 h -1 (heated beds) and these were significantly different to the control beds 3.9 ± 1.7 mg m -2 h -1 . No relationship between earthworm density and nitrous oxide flux was found for the large-scale beds. However, in a subsequent laboratory experiment, nitrous oxide emissions were positively correlated with earthworm density (R 2 = 0.76). Maintaining moderate bed temperatures for vermicomposting systems during low ambient temperatures can significantly increase earthworm density. Vermicomposting systems have the capacity to emit high levels of nitrous oxide and earthworms appear to be primarily responsible for this. The environmental impact from nitrous oxide emissions appears to be comparable to other waste processing operations. Further research is required into ways of minimising emissions especially from vermicomposting systems operating at high earthworm densities and high waste processing rates.
1] Sulfate in acid rain is known to suppress methane (CH 4 ) emissions from natural freshwater we... more 1] Sulfate in acid rain is known to suppress methane (CH 4 ) emissions from natural freshwater wetlands. Here we examine the possibility that CH 4 emissions from rice agriculture may be similarly affected by acid rain, a major and increasing pollution problem in Asia. Our findings suggest that acid rain rates of SO 4 2À deposition may help to reduce CH 4 emissions from rice agriculture. Emissions from rice plants treated with simulated acid rain at levels of SO 4 2À consistent with the range of deposition in Asia were reduced by 24% during the grain filling and ripening stage of the rice season which accounts for 50% of the overall CH 4 that is normally emitted in a rice season. A single application of SO 4 2À at a comparable level reduced CH 4 emission by 43%. We hypothesize that the reduction in CH 4 emission may be due to a combination of effects. The first mechanism is that the low rates of SO 4 2À may be sufficient to boost yields of rice and, in so doing, may cause a reduction in root exudates to the rhizosphere, a key substrate source for methanogenesis. Decreasing a major substrate source for methanogens is also likely to intensify competition with sulfate-reducing microorganisms for whom prior SO 4 2À limitation had been lifted by the simulated acid rain S deposition. Citation: Gauci, V., N. B. Dise, G. Howell, and M. E. Jenkins (2008), Suppression of rice methane emission by sulfate deposition in simulated acid rain,
The aim of this study was to determine the effect of thermophilic pre-composting followed by verm... more The aim of this study was to determine the effect of thermophilic pre-composting followed by vermicomposting on compost characteristics compared with thermophilic pre-composting and windrow composting. Source segregated household waste was thermophilically composted (14 days) to sanitise the waste. Organic matter and nitrogen losses were 9% and 5% respectively. The waste was then matured (84 days) using either vermicomposting beds (n ¼ 5) or composting windrows (n ¼ 5). At the end of the 98 days processing there was a significantly greater mass (P < 0.01) of fine particles (<10 mm) in the vermicomposting beds (65.3% m:m) compared with the compost windrows (36.9% m:m) suggesting enhanced fragmentation of the paper-based feedstock components by the earthworms. When screened, the windrow compost (<10 mm) contained significantly higher (P < 0.01) concentrations of total N, P and K and total Cu (P < 0.01), Pb (P < 0.001), Ni (P < 0.05) and Cd (P < 0.01). Significantly higher levels of electrical conductivity (EC) 3.08 mS.cm (P < 0.001) and water-soluble K 6366 mg kg À1 (P < 0.01) were recorded for the windrow compost compared with the vermicompost (1.78 mS.cm; 3328 mg kg À1 ). The vermicompost NO 3 concentration (2660 mg kg À1 ) was significantly higher (P < 0.05) than for the windrow compost (1531 mg kg À1 ). In a programme of plant response tests based on B.S.I. PAS 100 (2005), the screened (<10 mm) vermicompost and windrow compost performed comparably when formulated into growing media based on equalising EC levels.
Large individual applications of SO42- (102-103 kg SO42--S/ha) are known to suppress methane emis... more Large individual applications of SO42- (102-103 kg SO42--S/ha) are known to suppress methane emissions from rice paddies by up to ~70%. The application of large quantities of SO42- amendments to rice paddies has therefore been proposed as a greenhouse gas mitigation strategy. In a similar system, natural peatlands, research has established that very low rates of SO4^{2- } deposition (~25
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic was... more The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25-75 mL min −1 , although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.
This report provides a critical review of available evidence as to how effectively the various ca... more This report provides a critical review of available evidence as to how effectively the various categories and configurations of biofilter reduce bioaerosol and odour emissions from composting facilities.
Suppression of rice methane production and emission by low dose sulfate application
Large individual applications of SO 4 2- (10 2 -10 3 kg SO 4 2- -S/ha) are known to suppress meth... more Large individual applications of SO 4 2- (10 2 -10 3 kg SO 4 2- -S/ha) are known to suppress methane emissions from rice paddies by up to ~70%. The application of large quantities of SO 4 2- amendments to rice paddies has therefore been proposed as a greenhouse gas mitigation strategy. In a similar system, natural peatlands, research has established that very low rates of SO 4 2- deposition (~25 kg SO 4 2- -S/ha/yr as small weekly pulses), similar to those of regions experiencing acid rain pollution, suppress methane emissions by as much as 30-40%. It is thought that this is due to stimulation of sulfate-reducing microbial populations that out-compete methane producers for substrates. Given that acid rain S pollution is forecast to increase in Asia, the major rice growing region, we sought to establish the potential for acid rain to suppress CH 4 emission from rice agro-ecosystems by experimentally simulating acid rain inputs of S deposition to rice mesocosms in the laboratory. We u...
Safety in Composting Halls: Managing the risks from Carbon Monoxide
The importance of fitting the correct sensors for carbon monoxide monitoring in enclosed composti... more The importance of fitting the correct sensors for carbon monoxide monitoring in enclosed composting facilities has been highlighted by recent research conducted by the Open University, in collaboration with Amey Ltd. The research was commissioned due to concern about the frequency of alarm activations from carbon monoxide personal safety monitors within the composting facility of an MBT (Mechanical Biological Treatment) plant. Further investigation confirmed the presence of carbon monoxide in the compost hall, though at levels below the 30 ppm alarm threshold. However, nonhazardous levels of hydrogen were also present and caused interference to gas safety monitors, leading to false alarms for high carbon monoxide.
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic was... more The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25-75 mL min −1 , although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.
The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic was... more The ORG0020 dynamic respiration test is effective at distinguishing source segregated organic waste derived composts across a wide range of stabilities when compared to other standard tests; however, using the original diaphragm pump and manifold setup, the test is affected by variability in flow rate with time and across sample replicate vessels. Here, we demonstrate the use of a multichannel peristaltic pump to deliver a more consistent air flow to individual vessels. Using finished and unfinished industry compost samples from different sites with varying stabilities, we provide evidence of greater precision of the modified setup compared to the original. Furthermore, the reduced need for air flow adjustment resulted in improved running cost efficiency with less labour demand. Analysis of compost sample oxygen demand supports the current test air flow rate of 25-75 mL min −1 , although the improved air flow control will enable future narrowing of the acceptable range for better inter-laboratory performance.
Static, dynamic and inoculum augmented respiration based test assessment for determining in-vessel compost stability
Waste Management, 2015
The purpose of this work was to evaluate compost (and related industry) stability tests given rec... more The purpose of this work was to evaluate compost (and related industry) stability tests given recent large-scale changes to feedstock, processing techniques and compost market requirements. Five stability tests (ORG0020, DR4, Dewar self-heating, oxygen update rate (OUR) and static respiration) were evaluated on composts from ten in-vessel composting sites. Spearman rank correlation coefficients were strong for the ORG0020, OUR and DR4 (both CO2 and O2 measurement), however, OUR results required data extrapolation for highly active compost samples. By comparison the Dewar self-heating and static respiration tests had weaker correlations, in part the result of under reporting highly active, low pH samples. The findings suggest that despite differences in pre-incubation period both dynamic respiration tests (ORG0020 and DR4) are best suited to deal with the wide range of compost stabilities found.
A large-scale, outdoor vermicomposting system was monitored for 80 weeks. Earthworm populations w... more A large-scale, outdoor vermicomposting system was monitored for 80 weeks. Earthworm populations were recorded for 60 weeks in unheated beds operating at ambient temperatures (34 weeks at 6.3 ± 2.3°C) and in heated beds controlled at 13.7 ± 0.8°C for 34 weeks. Both blocks of beds were at ambient temperatures for the remaining 26 weeks. Earthworm biomass and the numbers of hatchlings and cocoons produced for the heated beds were found to be significantly greater than for the unheated beds. Nitrous oxide fluxes in winter (week 60) were 3.2 ± 0.3 mg m -2 h -1 (unheated beds), 1.8 ± 0.3 mg m -2 h -1 (heated beds), and these were significantly different to the control beds (0.1 ± 0.0 mg m -2 h -1 ). Emissions during summer (week 80) were 20.1 ± 3.0 mg m -2 h -1 (unheated beds), 21.3 ± 2.8 mg m -2 h -1 (heated beds) and these were significantly different to the control beds 3.9 ± 1.7 mg m -2 h -1 . No relationship between earthworm density and nitrous oxide flux was found for the large-scale beds. However, in a subsequent laboratory experiment, nitrous oxide emissions were positively correlated with earthworm density (R 2 = 0.76). Maintaining moderate bed temperatures for vermicomposting systems during low ambient temperatures can significantly increase earthworm density. Vermicomposting systems have the capacity to emit high levels of nitrous oxide and earthworms appear to be primarily responsible for this. The environmental impact from nitrous oxide emissions appears to be comparable to other waste processing operations. Further research is required into ways of minimising emissions especially from vermicomposting systems operating at high earthworm densities and high waste processing rates.
1] Sulfate in acid rain is known to suppress methane (CH 4 ) emissions from natural freshwater we... more 1] Sulfate in acid rain is known to suppress methane (CH 4 ) emissions from natural freshwater wetlands. Here we examine the possibility that CH 4 emissions from rice agriculture may be similarly affected by acid rain, a major and increasing pollution problem in Asia. Our findings suggest that acid rain rates of SO 4 2À deposition may help to reduce CH 4 emissions from rice agriculture. Emissions from rice plants treated with simulated acid rain at levels of SO 4 2À consistent with the range of deposition in Asia were reduced by 24% during the grain filling and ripening stage of the rice season which accounts for 50% of the overall CH 4 that is normally emitted in a rice season. A single application of SO 4 2À at a comparable level reduced CH 4 emission by 43%. We hypothesize that the reduction in CH 4 emission may be due to a combination of effects. The first mechanism is that the low rates of SO 4 2À may be sufficient to boost yields of rice and, in so doing, may cause a reduction in root exudates to the rhizosphere, a key substrate source for methanogenesis. Decreasing a major substrate source for methanogens is also likely to intensify competition with sulfate-reducing microorganisms for whom prior SO 4 2À limitation had been lifted by the simulated acid rain S deposition. Citation: Gauci, V., N. B. Dise, G. Howell, and M. E. Jenkins (2008), Suppression of rice methane emission by sulfate deposition in simulated acid rain,
The aim of this study was to determine the effect of thermophilic pre-composting followed by verm... more The aim of this study was to determine the effect of thermophilic pre-composting followed by vermicomposting on compost characteristics compared with thermophilic pre-composting and windrow composting. Source segregated household waste was thermophilically composted (14 days) to sanitise the waste. Organic matter and nitrogen losses were 9% and 5% respectively. The waste was then matured (84 days) using either vermicomposting beds (n ¼ 5) or composting windrows (n ¼ 5). At the end of the 98 days processing there was a significantly greater mass (P < 0.01) of fine particles (<10 mm) in the vermicomposting beds (65.3% m:m) compared with the compost windrows (36.9% m:m) suggesting enhanced fragmentation of the paper-based feedstock components by the earthworms. When screened, the windrow compost (<10 mm) contained significantly higher (P < 0.01) concentrations of total N, P and K and total Cu (P < 0.01), Pb (P < 0.001), Ni (P < 0.05) and Cd (P < 0.01). Significantly higher levels of electrical conductivity (EC) 3.08 mS.cm (P < 0.001) and water-soluble K 6366 mg kg À1 (P < 0.01) were recorded for the windrow compost compared with the vermicompost (1.78 mS.cm; 3328 mg kg À1 ). The vermicompost NO 3 concentration (2660 mg kg À1 ) was significantly higher (P < 0.05) than for the windrow compost (1531 mg kg À1 ). In a programme of plant response tests based on B.S.I. PAS 100 (2005), the screened (<10 mm) vermicompost and windrow compost performed comparably when formulated into growing media based on equalising EC levels.
Large individual applications of SO42- (102-103 kg SO42--S/ha) are known to suppress methane emis... more Large individual applications of SO42- (102-103 kg SO42--S/ha) are known to suppress methane emissions from rice paddies by up to ~70%. The application of large quantities of SO42- amendments to rice paddies has therefore been proposed as a greenhouse gas mitigation strategy. In a similar system, natural peatlands, research has established that very low rates of SO4^{2- } deposition (~25
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