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- PublicationHydrogen sulphide gas production from spent mushroom compost under field and laboratory conditionsHydrogen sulphide (H2S) gas production was monitored during the disturbance of four heaps of Spent Mushroom Compost (SMC) that were stored for up to 12 months either outdoors or under cover (indoors). QRAE (www.raesystems.eu) and ITX (www.indsci.com) gas monitors with data logging facilities were used to measure the 10-second average concentration of H2S released into the air above the heaps of SMC as they were being disturbed. The highest concentrations of up to 2083 ppm were detected for the outdoor stored material in comparison to concentrations of up to 687 ppm detected for indoor stored material. Outdoor stored SMC had higher moisture contents (66-72%) compared to indoor stored material (53-65%). Laboratory studies were conducted to study the effects of moisture content (69 – 85%) and temperature (35ºC or 45ºC) on H2S production from fresh un-steamed and steamed samples of SMC. The H2S gas concentration in the head space of the incubation vessels was measured every 24 hours for 3 days. Un-steamed SMC produced higher levels of H2S than steamed SMC and in general the higher the moisture content the higher the H2S concentration. Higher concentrations of H2S were also produced with the higher incubation temperature of 45 ºC. These results suggest that the high levels of H2S detected during disturbance of stored SMC are heavily influenced by moisture content. The higher rates of H2S production at 45 ºC also suggest that thermophilic microorganisms are involved in the process. Health and Safety aspects of H2S production from stored SMC are discussed
- PublicationFertiliser characteristics of stored spent mushroom substrate as a sustainable source of nutrients and organic matter for tillage, grassland and agricultural soilsSpent mushroom substrate (SMS) is an organic manure that can be used with advantage in agriculture. Under European Union (EU) (Good Agricultural Practice for Protection of Waters) Regulations, SMS cannot be applied to land over the winter months and must be stored on concrete surfaces, either covered or uncovered, to prevent nutrient-rich runoff seeping into groundwater. Spent mushroom substrate at four storage facilities, two covered and two uncovered, was analysed for physical and chemical characteristics after storage for up to 12 mo. Significant differences (P<0.05) were identified for all parameters across the four sites, except for pH, but there were no consistent differences that correlated with uncovered or covered storage conditions. The content of nitrogen (N) and manganese (Mn) was significantly lower in uncovered SMS, while the content of iron (Fe) and copper (Cu) was significantly higher. The chemical nitrogen-phospous-potassium (NPK) fertiliser equivalent value of SMS, when applied at a rate of 10 t/ha, was between €105 and €191 per hectare. Nitrogen-phospous-potassium concentrations per kg wet weight were all higher in SMS that was stored under cover, meaning higher chemical fertiliser savings are possible. The high pH of stored SMS (7.8–8.1) means it could be used with good effect on acid soils instead of ground limestone. The low bulk density of SMS (0.545–0.593 g/cm 3) makes it an ideal amendment to soils to improve soil structure and quality. There is some variability in the nutrient content of SMS from different sources, so it is advisable to get the material analysed when including in nutrient management plans.
354Scopus© Citations 2
- PublicationHydrogen sulfide gas emissions in the human-occupied zone during disturbance and removal of stored spent mushroom compostHydrogen sulfide (H2S) gas levels were monitored in the human-occupied zone at four spent mushroom compost (SMC) storage sites during removal of SMC for application on agricultural land. During SMC removal operations, H2S gas monitors were mounted on the outside of the tractor, positioned at the SMC periphery, and worn by individual tractor drivers. The highest H2S concentrations (10 s average) detected outside the tractor, at the SMC periphery, and for the tractor driver were, respectively, 454, 249, and 100 ppm for the outdoor sites and 214, 75, and 51 ppm for the indoor sites. The highest short-term exposure values (STEV, over a 15 min period) outside the tractor, at the SMC periphery, and for the tractor driver were 147, 55, and 86 ppm for the outdoor sites and 19, 9, and 10 ppm for the indoor sites. The values exceeded the current maximum permissible concentration limit of 10 ppm for all the sites except for the SMC periphery and tractor driver at the indoor sites. Results suggest that H2S levels detected at indoor storage sites during SMC removal are lower compared to outdoor storage sites. Results indicate that there is a substantial health and safety risk associated with working in the vicinity of stored SMC when it is being disturbed and removed for land application, and that the risk is great for the tractor driver. This article discusses possible control measures and lists recommendations to reduce the risks.
694Scopus© Citations 1
- PublicationHydrogen sulfide gas emissions during disturbance and removal of stored spent mushroom compostSpent mushroom compost (SMC) is a by-product of the mushroom industry that is used as an agricultural fertilizer. In Europe its storage and use are governed by the EU Nitrates Directive 91/676/EEC to protect waterways against pollution by nitrates. A health and safety risk was identified during the removal and spreading of stored SMC onto land whereby stored SMC released high levels of toxic H2S gas into the atmosphere when disturbed. Emissions of H2S were monitored at two outdoor and two indoor locations where stored SMC was being removed for spreading on land. A repeating peak-trough pattern of H2S emissions was detected at all sites with peaks corresponding to periods of active disturbance of SMC. The highest H2S concentrations (10 s average) detected at the SMC face were: 680 and 2083 ppm at outdoor Sites 1 and 2; and 687 and 89 ppm at indoor Sites 3 and 4, respectively. Higher concentrations of H2S were released from older SMC compared to younger material. Indoor-stored SMC had lower moisture content (53% to 65%) compared to outdoor-stored material (66% to 72%) while the temperature of indoor-stored SMC was higher (33 ºC to 51ºC) compared to outdoor-stored material (24ºC to 36ºC). The current Short Term Exposure Limit (STEL) of 10 ppm was exceeded at all sites except Site 4, which was smaller than the others, indicating a significant health and safety risk associated with working in the vicinity of stored SMC when it is being actively disturbed. Results suggest that SMC stored in small heaps (600 m3) under cover, emits less H2S during disturbance and removal compared to SMC stored in large heaps (>1500 m3) outdoors. This should be taken into consideration in the design, construction and management of SMC storage facilities. Health and safety protocols should be in place at SMC storage facilities to cover the risks of exposure to toxic H2S gas during disturbance of stored SMC.
585Scopus© Citations 7