Windrow Piles Research Articles

A global meta-analysis of greenhouse gas emissions and carbon and nitrogen losses during livestock manure composting: Influencing factors and mitigation strategies

The management of manure composting contributes to alleviate the global greenhouse effect. To improve our understanding of this process, we conducted a meta-analysis of 371 observations from 87 published studies in 11 countries. The results showed that the difference in nitrogen content in feces significantly affected the greenhouse gas (GHG) emissions and nutrient losses of subsequent composting, with NH3-N, CO2-C, and CH4-C losses all increasing with its rise. Windrow pile composting (especially compared to trough composting) had lower GHG emissions and nutrient loss. C/N ratio, aeration rate, and pH value significantly affected NH3 emission, and a decrease in the latter two can reduce it by 31.8 % and 42.5 %, respectively. Decreasing the moisture content or increasing the turning frequency could decrease CH4 by 31.8 % and 62.6 %, respectively. The addition of biochar or superphosphate had a synergistic emission reduction. The emission reduction of N2O and CH4 by biochar was more prominent (44 % and 43.6 %), while superphosphate on NH3 (38.0 %) was better. And the latter was more suitable if added in 10–20 % of dry weight. Dicyandiamide was the only chemical additive (59.4 %) with better N2O emission reduction performance. Microbial agents with different functions had certain effects on NH3-N emission reduction, while the mature compost had a certain effect on N2O-N emissions (67.0 %). In general, N2O had the highest contribution to the greenhouse effect during composting (74.22 %).

MICRO-POSITIVE PRESSURE AERATION FOR WINDROW COMPOSTING OF MUNICIPAL SOLID WASTE IN CHANDIGARH: AN OPPORTUNITY IN A CARBON CONSCIOUS WORLD FOR COMBATING CLIMATE CHANGE

The present study was a pilot project initiated in Chandigarh to discuss the feasibility andeffectiveness of adept schemes for successful co-composting of green waste and kitchen waste(food and fruit) waste in 64 m2 open covered windrows with bulking grass layer bottom upventilation system generating micro-positive pressure, making windrow piles aerobic, organolepticwith reduced green -house gases (GHGs) emission. The compost temperature profile shows twothermophilic peaks; first in bioreactor (74 oC) and second in charging pit (76.2 oC) after 40 days oninoculation and the high temperature fermentation was maintained for 80days. The high qualityfinal compost has 40oC temperature, 7.6pH, 42% moisture content, 3.36ds/m electrical conductivityand 25 C/N ratio. The main objective of the present study is to analyze and overview theconfiguration technology and analytical parameters to limit the global temperature rise to 1.5 oC,to meet the goals of the Paris agreement to avoid catastrophic impacts of climate change. Theinference of the study is the mitigation of carbon leakage, generating 346.7 carbon credits and 564quintals organic compost worth 25 lakhs to achieve sustainable zero waste future.

Methane and nitrous oxide emissions from shallow windrow piles for biostabilisation of municipal solid waste

ABSTRACT Shallow windrow piles were applied as a low-cost option for biostabilisation of municipal solid wastes (MSW) prior to their utilization as refuse-derived fuel (RDF). A considerable amount of greenhouse gas (GHG) emissions can be emitted during the biostabilisation of MSW, especially when in operation under high moisture conditions such as there are in tropical Asia. This study investigated the emission of methane (CH4) and nitrous oxide (N2O) from shallow windrow piles – with heights of 0.5–1.0 m – for the stabilization of MSW at a full-scale facility in Thailand. Measurements of CH4, CO2, and N2O emissions using the static-chamber method revealed high spatial heterogeneity characteristics in all zones with different waste ages. Peak methane emissions were observed after four months of biostabilisation. The average spatial methane emissions from the waste piles ranged from 7.33 to 26.88 g m−2 d−1 (14.86 g m−2 d−1, on average). The CH4 generation-rate constant was within the range of 3.3 to 4.0 yr−1, which is higher than that reported – about 2.20–3.50 yr−1 – from a deep windrow pile (3.5–4.0 m height). The spatial distribution of N2O emissions was in the range of 4.51–199.14 mg N2O t−1dry wt.d−1 (6.6–111.7 mg N2O m−2 d−1), similar to those previously studied from landfill operations. This shallow windrow pile technique can be applied as low-cost technology for biostabilisation of MSW in developing countries, where land area is available. Implications: Shallow windrow pile was applied as a low-cost option for biological treatment of municipal solid waste in developing countries where land area is available. This study evaluated the greenhouse gas emission characteristics during the operation of windrow pile. The findings suggest that the emission rates were varied spatially with waste ages in different zones. Higher methane generation rate constant was derived from shallow window pile as compared to deep windrow pile. The methane and nitrous oxide emission factors were derived.

Potential of Producing Compost from Source-Separated Municipal Organic Waste (A Case Study in Shiraz, Iran)

Developing countries face serious environmental, social and economic challenges in managing different types of organic waste. Proper treatment strategies should be adopted by solid waste management systems in order to address these concerns. Among all of the treatment options for organic waste, composting is the most approved method as an effective strategy to divert solid waste from landfills. This experimental research aimed to examine the potential of producing compost from source-separated municipal organic waste in Shiraz, Iran. Market waste (fruits and vegetables) and garden waste (plant residues) were used as the raw input materials. They were subjected to the windrow pile composting method in an open site area. The process was monitored against several physical, chemical and biological parameters. In-situ measurements (temperature and moisture content) were carried out on a daily basis. Sampling and lab analyses were conducted over the period of the biological treatment. The final product was of acceptable moisture and nutrient levels, pH, Electrical Conductivity (EC), and Carbon/Nitrogen ratio. All of the analyzed compost samples had lower concentrations of heavy metals than the Iranian and German standards. Overall, the results obtained revealed that composting is a promising method for municipal organic waste treatment. The findings also imply the effectiveness of the source-separation collection method in the production of high-quality compost.

Changes in microbial populations during co-composting of dewatered sewage sludge with pruning wastes in windrow piles

Abstract. Nafez AH, Nikaeen M, Hassanzadeh A, Kadkhodaei S. 2020. Changes in microbial populations during co-composting of dewatered sewage sludge with pruning wastes in windrow piles. Biodiversitas 21: 4648-4655. The aim of this paper was to study the composting of sewage sludge (SS) and pruning waste as bulking agent with regard to abiotic factors and succession of functional microbial groups. To prepare the composting piles bulking agent and SS in volumetric ratios of 1:1 (TW1), 2:1(TW2), and 3:1(TW3) were used, and a pile of raw sludge was used as control. Samples for investigation were obtained from the composting piles at time intervals of 5-7 d. The temperature of the control pile and TW1 was just 37°C and did not reach the thermophilic phase. The number of thermophilic bacteria increased to 14 log CFU gDW-1 in the thermophilic phase. The salmonella was lost on the 47th and 19th days of the composting process, for TW2 and TW3, respectively. There was a significant correlation between mesophilic fungi with mesophilic bacteria (r=0.942, P<0.001). The majority of the microbial populations inspected revealed their maximum numbers towards the end of the thermophilic phase, with decreasing tendencies afterward. The number of evaluated microorganisms was controlled by differences in physicochemical parameters at different composting phases. The results revealed that the scheduling of the thermophilic period, as well as the microbial community and environmental situations, affects the microbial structure andTW2 had the best quality compared to other piles in achieving the best thermophilic phase and elimination of pathogenic microorganisms.

Potential of windrow food and green waste composting in Tunisia.

Solid waste management and disposal is one of the most significant challenges facing urban communities around the world. There is a wide range of alternative waste management options and strategies available for dealing with the notable increase in the waste stream. Composting is one of the most viable and efficient waste treatment options in terms of the reduction in the negative effects from the application of organic waste to soil. The experimental research aimed to examine the potential of producing compost from different organic waste streams in Tunisia. Two experimental windrow piles made from cooked and uncooked food and garden wastes were initiated and temporally monitored. The composting process was controlled in terms of temperature and moisture. Sampling was carried out over the period of the composting process. All of the collected samples were analyzed in terms of their physical, chemical, and biological properties; pH, C:N ratio, nitrification index (NI), microbiological tests, respiration activity (AT4), and heavy metal content. The quality of the final product was determined and compared with Tunisian and German standards. The findings demonstrated a significant reduction in the initial C:N ratio to about 15 by the end of the process. Additionally, the results showed that the compost produced appeared to be stable and was deemed to be class V finished compost; the NI was found to be around 1, while the AT4 was estimated to be lower than 6mg O2/g TS. Regarding the heavy metal content, the final products were characterized as having a lower concentration than those values set by Tunisian and German standards.

Monitoring of Biochemical Parameters and GHG Emissions in Bioaugmented Manure Composting

Composting is a sustainable alternative for the management of manure. In this study, the effects of bioaugmentation on cattle manure composting was investigated. In this study, two windrow piles were placed at 1.7 m in height, 2.1 m in bottom width, 0.6 m in top width, and 54 m in length. Microbial inoculum was added to pile 1, whereas the second pile was used as the control. After 17 days, the C:N ratio was reduced from 25.6 to 13.6 and the total nitrogen was increased from 1.89% to 3.36% in pile 1. The dominant bacteria identified in the compost samples belonged to the genera Clostridium, Bacillus, and Flavobacterium. Quantitative polymerase chain reaction indicated that the most commonly known pathogenic bacteria, Escherichia coli, Shigella, and Salmonella, were not detected in the finished material, indicating that the pathogenic microorganisms were inactivated by the composting process. Agronomic testing for cured compost indicated a C:N ratio of less than 15 and NH+4-N:NO3−-N ratio of less than 1. The whole process of windrow composting resulted in net greenhouse gas (GHG) emissions of 157.94 tCO2-e and a global warming factor (GWF) of 1.04 tCO2-e·t−1 manure composted. This study showed that although bioaugmentation is a feasible treatment method for manure, GHG emissions need to be monitored.

Enhanced composting as a way to a climate-friendly management of coffee by-products

This study investigated the performance of aerobic windrow systems by using coffee by-products and green waste to reduce gaseous emissions. Thereafter, a comparison with the current treatment and gaseous emissions at a Coffee Mill in Costa Rica was made. Two different studies where performed in Germany (pile I and II) and one study in a Coffee Mill in Costa Rica (pile III). Temperature, water content, and pH were the key parameters controlled over 35 days in all the systems. Moreover, CH4 emission rates were quantified by a FTIR and by a portable gas detector device where the emissions reached values 100 times higher when coffee by-products as a unique material for the composting process was used. Results show that highest emission rates during the composting process for pile I was 0.007 g(m2)−1 h−1, for pile II 0.006 g(m2)−1 h−1, and for pile III 3.1 g(m2)−1 h−1. It was found that CH4 emissions could be avoided if the mixture and the formation of the windrow piles were performed following the key parameter for composting, and the usage of additional material is used. With this, the reduction of CH4 emissions at the Mill in Costa Rica could be achieved in the future.

Greenhouse gas emission from windrow pile for mechanical biological treatment of municipal solid wastes in tropical climate

Methane emission characteristics of a full-scale windrow pile for municipal solid waste (MSW) treatment in Thailand were investigated. Surface emission rate, in-pile methane gas content and waste characteristics were observed over 14 months period. The results revealed average surface methane emission rate of 5.32 g/t dry wt./day, being largely fluctuated between 0.05 and 27.13 g/t dry wt./day. The methane emission from MBT windrow pile, during which 75% of organic wastes were decomposed, were comparatively lower than those reported for landfills and windrow composting operations. The precipitation affected gas emission especially during the initial phase of waste decomposition with gas production lag time ranged between 0.34 and 0.55 years. Positive correlation between methane emission rate from waste pile and precipitation was observed during methanogenic stage or gas rising stage when organic content in wastes was still high. The open windrows operated in tropic climate could facilitate a high degree of waste stabilization but they were not effective for the reduction of moisture from MSW required for utilization as refuse-derived fuel.

An Assessment of Chemical and Microbiological Properties of Different Types of Poultry Waste Compost Prepared by Bin and Windrow Composting System

The present study aimed to evaluate the physical, chemical, and microbiological characteristics of 4 different poultry waste (dead birds, hatchery waste, offal, and a mixture of all) processed under two composting systems (bin and windrow). For this purpose, 12 compost bins and 12 windrow piles having different poultry waste were placed according to 2 × 4 factorial arrangements under Completely Randomized Design. Treatments consisted of 2 composting systems (bin and windrow) and 4 compost types (dead birds, offal, hatchery waste, and a mixture of all). The bins were comprised of 3 compartments (primary, secondary, and curing) and filled with dead birds, offal, hatchery waste, and a mixture of all. A similar procedure was adopted for the windrow composting system. Samples from each experimental material were collected and analyzed for proximate, amino acid, mineral, and bacterial analysis during the initial and curing phase. Results revealed that the highest crude protein (CP) content was found in dead birds while the lowest in hatchery waste compost processed under both composting systems. The highest temperature was recorded in dead bird’s compost during the primary phase while the minimum was found in hatchery waste. Microbial count of salmonella, mycoplasma, E. coli, and total plate count was found minimum in all types of compost. Macrominerals like Na, K, and P were the highest in dead birds while the lowest in hatchery waste compost. It can be concluded that dead birds compost processed through bin composting system had ideal proximate composition having minimal pathogenic load with superior amino acid and mineral profile as compared to other waste materials.

Using of indigenous bulking agents (IBAs) in complementary stabilization and enhancing of dewatered sludge class B to class a on a full scale.

Different bulking agents are used in the compost of dewatered sludge (DWS). The aim of this study has been using of indigenous bulking agents (IBAs) in the enhancing of the DWS class of municipal wastewater from class B to class A and complementary stabilization of it for production of green manure in Sari city, Iran. Three IBAs including the Saccharum Wastes (SW), Citrus Purning Wastes (CPW) and Phragmites Australis (PA) from eight IBAs were selected to be compared with the sawdust (SD) that was as a control bulking agent. Five turned windrow piles were constructed on a full scale and on base of optimal C/N equal 25.All experiments were performed on the base of the standard methods on initial mix and final compost. Among five windrow piles, P5 was been the best pile with a weighting ratio of DWS to IBAs (DWS: SW: CPW: PA) equal 1: 0.2: 0.24: 0.28. Pile P1 with weighting ratio DWS: SW equal 1: 0.6, Pile P3 with weighting ratio DWS: PA equal 1: 0.84, Pile P2 with weighting ratio DWS: CPW equal 1: 0.73 and Pile P4 with weighting ratio DWS: SD equal 1: 0.57 were placed in the next rounds. The results showed that the class of DWS enhanced to Class A for about 80 to 97days and complementary stabilization of DWS by IBAs was done well and produced green manure in term of organic matter, potassium, germination index, PH, C/N and electrical conductivity had reached to the Grade 1 of Iran's manure 10716 standard and in term of phosphorus and moisture had reached to the Grade 2 of this standard. Also heavy metals were below the maximum permissible of standards. Using of IBAs, had a higher efficiency than the control bulking agent (sawdust) in enhancing sludge class and its stabilization, so that using of them in combination (mix of IBAs) had the highest efficiency and respectively, Saccharum Wastes (SW), Phragmites Australis (PA), Citrus pruning wastes (CPW) were placed in the next round, and sawdust was placed after them. By adding suitable IBAS, with an optimal ratio in turned windrow method, the class of DWS of sari WWTP enhanced to Class A and complementary stabilization of DWS has been well done and the produced green manure has been reached to agricultural standards and can be safely used in agriculture.

Biodegradation of oil tank bottom sludge using a new two-phase composting process: kinetics and effect of different bulking agents

In this study, the effect of adding various bulking agents on the performance of a two-phase composting method in bioremediation of petroleum compounds from oily sludge was surveyed. The utilized system included the primary stage composting (PSC) using 6 windrow piles and the secondary stage composting (SSC) using 6 in-vessel bioreactors. Various amounts and combinations of immature compost, mature compost, and green waste were blended with oil tank bottom sludge (OTBS). Then, the mixture was added to the PSC and SSC experiments and composted for a period of 12 and 6 weeks, respectively. The results showed that the degradation percentages of total petroleum hydrocarbons in the PSC and SSC experiments were 63.56–84.50% and 57.59–88.95%, respectively. The removal efficiency reached through the two-phase system was higher than that of the single-stage process. Biodegradation was fitted to the first- and second-order kinetic with the rate constants of 0.076–0.389 day−1 and 0.006–0.176 g kg−1 day−1, respectively. The bacteria identified from the composting mixtures were Bacillus sp., Pseudomonas sp., Staphylococcus sp., and Klebsiella sp. It was concluded that the two-stage composting system, as an inexpensive and efficient method, is practically applicable for remediation of OTBS.

Oily sludge biodegradation using a new two-phase composting method: Kinetics studies and effect of aeration rate and mode

Abstract In this research, the impact of active and passive aeration on the performance of a new two-phase composting process for biodegradation of storage tank oily sludge (STOS) was evaluated. The hyphenated method consisted of primary-stage composting (PSC) including three windrow piles and secondary-stage composting (SSC) including four in-vessel bioreactors. Various turning and aeration rates were tested in the PSC and SSC for 12 and 6 weeks, respectively. Results showed that the removal percentages of total petroleum hydrocarbons (TPH) in the PSC and SSC were in the range of 72.13–89.42 and 68.36–81.63%, respectively. An overall TPH removal of 90.07–94.23% reached through the two-stage system was higher than those of both the PSC and SSC alone. The turning and aeration rate of every 5 days and 1 l min−1 kg−1 were, respectively, determined as optimal values. TPH was degradation fitted to the first-order kinetics based on the rate constants and half-lives of 0.114–0.183 d−1 and 3.79–6.08 days for the PSC, and 0.191-0.296 d−1 and 2.34–3.63 days for the SSC, respectively. The bacteria of Staphylococcus sp., Pseudomonas sp., Proteus sp., and Bacillus sp. were isolated from the process. This study verified the effectiveness of the two-phase composting system in STOS bioremediation.

Monitoring of Composting Process Parameters: A Case Study in Jordan

This study aimed to monitor the composting process of the first small-scale segregated bio-waste composting scheme in Jordan to divert different types of organic wastes and to evaluate the final product quality, which can be recovered and used as compost. In this study, four experimental windrow piles were first initiated and temporally monitored. The composting process was monitored against temperature, moisture and oxygen content, indicating that the biological conditions were sufficiently developed. The monitored experimental process showed overall decreasing profiles versus composting time for moisture, organic carbon and carbon/nitrogen content, as well as overall increasing profiles for electrical conductivity and total nitrogen, which represented qualitative indications of progress in the process. The product quality was examined and assessed against the quality specifications of EU End of Waste Criteria for bio-waste, which has been subjected to composting, aiming to specify whether the different types of organic wastes that have undergone recovery cease to be waste and can be classified as high quality compost. More specifically, on the one hand the heavy metal concentrations (Cr, Cu, Ni, Cd, Pb, Zn and Hg) were within the set limits and much lower compared to the European standards. On the other hand, compost respiration in the samples varied from 3.6 to 15.3 mgO2/g dm, which, in turn, indicates that all the compost samples appeared to be stable and rated as class IV and V final products.

Bioremediation of storage tank bottom sludge by using a two-stage composting system: Effect of mixing ratio and nutrients addition

The effect of mixing ratio and nutrients addition on the efficiency of a two-stage composting system in removal of total petroleum hydrocarbons (TPH) from storage tank bottom sludge (STBS) was investigated. The system consisted of ten windrow piles as primary composting (PC) followed by four in-vessel reactors as secondary composting (SC). Various initial C/N/P and mixing ratios of STBS to immature compost (IC) were examined in the PC and SC for 12 and 6weeks, respectively. The removal rates of TPH in the two-stage system (93.72–95.24%) were higher than those in the single-stage one. Depending on the experiments, TPH biodegradation fitted to the first- and second-order kinetics with the rate constants of 0.051–0.334d−1 and 0.002–0.165gkg−1d−1, respectively. The bacteria identified were Pseudomonas sp., Bacillus sp., Klebsiella sp., Staphylococcus sp., and Proteus sp. The study verified that a two-stage composting system is effective in treating the STBS.

Resource Conservation by Effective Composting of Municipal Solid Waste in Sri Lanka – Optimum Moisture Range for the Bio-oxidative Phase

Waste is a resource. Municipal solid waste management is a great concern in Sri Lanka due to high water content and heterogeneity of the waste. Composting is one of the important, cost effective methods of management of biological waste in developing countries. This study was performed to determine the optimum moisture range for effective composting, which can be maintained throughout the bio-oxidative phase of the composting process to accelerate the decomposition rate and eventually get a better compost product. Four wind row piles were set up with moisture contents adjusted to 60% ± 10% (Control) for five weeks, 40% ± 10% (Pile A), 60% ± 10% (Pile B) and 80% ± 10% (Pile C) for 8 weeks. Moisture content of the control pile was lowered to a value of 40%± 10% during the last three weeks while other piles were maintained within the experimental moisture ranges for the eight weeks of composting cycle. According to the temperature profiles of the piles, pile B showed the best temperature level for microorganisms. Other physico-chemical parameters were not significantly different between piles. Therefore, moisture content of pile B (60% ± 10%) was selected as the optimum moisture range for the bio-oxidative phase in the composting process. Unskilled labourers can maintain that moisture level easily by performing the squeeze test for the moisture.

Physical covering for control of Escherichia coli O157:H7 and Salmonella spp. in static and windrow composting processes.

This study investigated the effect of a 30-cm covering of finished compost (FC) on survival of Escherichia coli O157:H7 and Salmonella spp. in active static and windrow composting systems. Feedstocks inoculated with E. coli O157:H7 (7.41 log CFU/g) and Salmonella (6.46 log CFU/g) were placed in biosentry tubes (7.5-cm diameter, 30-cm height) at three locations: (i and ii) two opposing sides at the interface between the FC cover layer (where present) and the feedstock material (each positioned approximately 10 cm below the pile's surface) and (iii) an internal location (top) (approximately 30 cm below the surface). On specific sampling days, surviving populations of inoculated E. coli O157:H7 and Salmonella, generic E. coli, and coliforms in compost samples were determined. Salmonella spp. were reduced significantly within 24 h in windrow piles and were below the detection limit after 3 and 7 days at internal locations of windrow and static piles containing FC covering, respectively. Likewise, E. coli O157:H7 was undetectable after 1 day in windrow piles covered with finished compost. Use of FC as a covering layer significantly increased the number of days that temperatures in the windrows remained ≥55°C at all locations and in static piles at internal locations. These time-temperature exposures resulted in rapid reduction of inoculated pathogens, and the rate of bacterial reduction was rapid in windrow piles. The sample location significantly influenced the survival of these pathogens at internal locations compared to that at interface locations of piles. Finished compost covering of compost piles aids in the reduction of pathogens during the composting process.

Effect of forced ventilation during composting on Agaricus bisporus substrate selectivity

The production of mushroom substrate with limited aeration in phase I composting was studied. A standard mushroom compost made in windrow piles with forced aeration was compared with the experimental compost prepared under limited aeration during part of phase I. Limited ventilation resulted in a product with chemical parameters similar to those produced with full aeration. Despite this, loss of compost selectivity was observed. When aeration was limited during part of the composting process, 50% mushroom yield losses caused by strong infestation of Trichoderma aggressivum were observed. Limited ventilation in part of phase I resulted in a reduction of redox potential, increase of pH, and concentration of free ammonia, and thus disturbed the transformation of compost into selective medium for Agaricus. Mushroom yield correlated with redox potential in the compost, and prolonged high concentration of free ammonia was the main factor in delayed but faster organic matter degradation in non-ventilated compost. The changes of redox potential and electrical conductivity in the course of composting can be useful tools for process control and evaluation of the compost quality potential and susceptibility to green mould infestation.

Spatial variability of heating profiles in windrowed poultry litter

SUMMARY In-house windrow composting of broiler litter has been suggested as a means to reduce microbial populations between flocks. Published time-temperature goals are used to determine the success of the composting process for microbial reductions. Spatial and temporal density of temperature measurement can influence the accuracy in determining what portion of a windrow section has achieved specified time-temperature goals. In this study, windrow section temperature was recorded every 2 min for 7 d on a 10 × 10-cm grid in 183 (width) × 91 cm (height) windrow sections. In 5 windrow sections, ordinary kriging was used to predict the mean portion of the windrow cross-sectional area reaching time-temperature goals of 40°C for 120 h, 50°C for 24 h, and 55°C for 4 h. Based on these results, 88.5 ± 2.0%, 80.8 ± 3.9%, and 38.4 ± 11.7% of the windrow cross-sectional area can be expected to reach published microbial reduction time-temperature goals of 40°C for 120 h, 50°C for 24 h, and 55°C for 4 h, respectively. This study illustrates the need to monitor temperature at multiple locations within windrowed litter to characterize heating profiles. Temporal and spatial sampling densities must be standardized to properly characterize temperature profiles in windrowed broiler litter. Additional research should be conducted to determine the degree of pathogen destruction achieved in the various time-temperature regions of the windrow pile. This study was useful in illustrating the efficacy (proportion of windrow cross-section) of windrow composting as a treatment method for reducing microbial populations as measured by time-temperature goals in used broiler litter.

Fuel quality changes in full tree logging residue during storage in roadside slash piles in Northwestern Ontario

The procurement of logging residue for energy production can be uneconomical due to high moisture content and low gross calorific value. High moisture content in biomass lowers the energy density and transportation becomes less efficient. Logging residue, from full tree logging operations stored in roadside beehive and windrow piles, were examined to determine the effect of storage method and duration on fuel quality in northwestern Ontario, Canada. The fuel attributes assessed were moisture content, gross calorific value and ash content. Windrows displayed lower moisture content than beehives. Softwoods generally displayed lower moisture content and higher gross calorific values than hardwoods. Smaller diameter stems displayed higher gross calorific value and ash content than larger diameter stems. The moisture content (green basis) reduced from a green state to 15.1% after two years of storage in roadside slash piles, whereas gross calorific value and ash content did not change significantly with storage time. The gross calorific values ranged from 19.5 to 23.1 MJ kg −1 and the ash content ranged from 0.4% to 8.4% for all species, components and storage years. The study demonstrates that the storage regime plays a significant role on the fuel quality of logging residue. Proper storage and drying techniques improve the fuel quality and net energy yield from logging residue biomass, thereby leading to an overall cost reduction of the biomass feedstock. ► Feasibility of using full tree logging residues for bioenergy investigated. ► Effect of storage duration, pile type, species and diameter effect on fuel quality. ► Fuel qualities measured were gross calorific value, ash and moisture content. ► Moisture reduced during storage, no effect on gross calorific value or ash content. ► Field storage for certain period can improve energy yield and transportation cost.