G.W. Price

Evaluation of three composting systems for the management of spent coffee grounds

This study was conducted to evaluate the optimum composting approach for the management of spent coffee grounds from the restaurant and ready-to-serve coffee industry. Three composting systems were assessed, including in-vessel composting, vermicomposting bins, and aerated static pile bin composting, over study periods ranging from 47 to 98 days. Total carbon content was reduced by 5-7% in the spent coffee ground treatments across the three composting systems. Nitrogen and other mineral nutrient contents were conserved or enhanced from the initial to the final composts in all the composting systems assessed. Earthworm growth and survival (15-80%) was reduced in all the treatments but mortality rates were lower in coffee treatments with cardboard additions. A decline in earthworm mortality with cardboard additions was the result of reduced exposure to organic compounds and chemicals released through the decomposition of spent coffee grounds.

Effects of Biochar Amendments on Soil Microbial Biomass and Activity

Environmental benefits reported in the literature of using biochar as a soil amendment are generally increased microbial activity and reduced greenhouse gas (GHG) emissions. This study determined the effects of amendment with biomass feedstocks (spent coffee grounds, wood pellets, and horse bedding compost) and that of biochars (700°C) produced from these feedstocks on soil microbial biomass (C and N) and activity. Soils were amended with these substrates at 0.75% by weight and incubated for up to 175 d under laboratory conditions. Biochar residual effects on soil microbial activity were also studied by amending these soils with either ammonium nitrate (NHNO, 35 mg N kg) or with glucose (864 mg C kg) plus NHNO. Soil microbial biomass C and N, net N mineralization, and CO, NO, and CH emissions were measured. Amendment with biomass feedstocks significantly increased soil microbial biomass and activity, whereas amendment with the biochars had no significant effect. Also, biochar amendment had no significant effect on either net N mineralization or NO and CH emissions from soil. These results indicate that production of biochars at this high temperature eliminated potential substrates. Microbial biomass C in biochar-amended and unamended soils was not significantly different following additions of NHNO or glucose plus NHNO, suggesting that microbial access to otherwise labile C and N was not affected. This study shows that biochars produced at 700°C, regardless of feedstock source, do not enhance soil microbial biomass or activity.

Effect of soil biochar concentration on the mitigation of emerging organic contaminant uptake in lettuce

Although crop uptake of emerging organic contaminants (EOC) from irrigation water and soils has been previously reported, successful mitigation strategies have not yet been established. In this study, soil was amended with a wood-based biochar (BC) at two rates (0, 2.5 and 5% w/w) to evaluate the effect on mitigation of EOC uptake (i.e. bisphenol A, caffeine, carbamazepine, clofibric acid, furosemide, ibuprofen, methyl dihydrojasmonate, tris(2-chloroethyl)phosphate, triclosan, and tonalide) in lettuce (Lactuca sativa L.). After 28 days of irrigation with water containing EOCs at 15μgL-1, the average EOC concentration in roots and leaves decreased by 20-76% in biochar amended soil relative to non BC-amended soil. In addition, the enantiomeric fractions (EF) of ibuprofen (IBU) in biochar amended soils (EF=0.58) and unamended soils (EF=0.76) suggest that the IBU sorbed fraction in BC is more recalcitrant to its biodegradation.

Inactivation of Aleutian mink disease virus through high temperature exposure in vitro and under field-based composting conditions

Disposal of manure contaminated with Aleutian mink disease virus (AMDV) is a significant concern to the mink industry. Inactivation of AMDV under field conditions has received limited attention in the scientific literature. We evaluated the thermal inactivation of AMDV in vitro and during composting of mink manure. Spleen homogenate containing AMDV was heated under controlled conditions at 45°C, 55°C, and 65°C for 3 days. Results of the in vitro study identified complete absence of viral replication in mink at 65°C only. Next, manure-mixed AMDV packed in polyester pouches was inserted in different layers of three replicate mink manure compost piles. The virus was retrieved after the compost piles had undergone a heating period and subsequently returned to ambient temperatures. Temperature regimes in the compost piles were categorized as ≥65°C, ≥60-64°C, and ≥55-59°C. Initially, layer-wise composite virus samples were assayed for virus replication in mink. Twenty-one-day post-inoculation (p.i.) plasma tested for AMDV and antibodies indicated infection in 40%, 80%, and 100% of mink inoculated from samples originating from the top, center and bottom layers of the piles, respectively. Subsequently, the virus was extracted from individual pouches in compost layers achieving thermal activity ≥65°C and was tested in mink. No antibodies or virus was detected in plasma taken weekly up to day 21 p.i. PCR data of bone marrow and lymph nodes collected on day 21 p.i. also showed no AMDV. However, mink that received virus from positive control manure indicated infection in their plasma as early as 1 week p.i.

Lethal and sub-lethal effects of triclosan toxicity to the earthworm Eisenia fetida assessed through GC-MS metabolomics.

Triclosan (TCS) is a ubiquitous contaminant in municipal biosolids, which has also been detected in soils and earthworms sampled from agricultural fields amended with biosolids. The goal of this study was to evaluate the toxicity of TCS to earthworms using a metabolomics-based approach for an improved interpretation of toxicity. Toxicity of TCS was assessed using the OECD Method 207 filter paper contact test measuring the endpoints of weight loss, mortality, and ten metabolites determined by GC-MS. Eight earthworms were exposed as individual replicates to six concentrations of triclosan (0, 0.0001, 0.001, 0.01, 0.1, and 1mg TCS cm-2) on filter paper, with mortality assessed after 6, 24 and 48h. Mortalities were first observed at 24h, with 100% mortality in the 1 and 0.1mgcm-2 treatments. Worms at 1mgcm-2 lost most of their coelomic fluid before they could be sampled. The 48h LC50 for triclosan was estimated to be 0.006 and 0.008mgcm-2 by a linear and logistic model, respectively. Based on the LC50, triclosan is relatively more toxic to earthworms than a number of other emerging contaminants, but is less toxic than other chlorophenols and many pesticides. Alanine, valine, leucine, serine, phenylalanine, putrescine, spermidine, mannitol, and inositol were significantly different between treatments, although changes were most often associated with mortality rather than triclosan exposure. An increase in putrescine and decrease in amino acids, polyols, and spermidine were associated with mortality, suggesting decomposition had begun. Principal components analysis did not reveal evidence of metabolic impacts at sub-lethal concentrations. However, there were changes in the pattern of correlations between metabolite pairs in surviving worms at both 0.0001 and 0.001mgcm-2 exposure compared to the control.

Fate and transport modeling of phthalate esters from biosolid amended soil under corn cultivation

Phthalate esters (PAEs) are prevalent in the environment due to the broad range of industrial, agriculture and domestic applications. The ubiquitous use of PAEs has resulted in their potential to reach groundwater sources through application of agri-chemicals and municipal biosolids. A study was conducted to monitor the fate and transport of seven commonly detected PAEs in the environment including: dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP), bis(di-ethyl hexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), dipentyl phthalate (DPP), and di-n-butyl phthalate (DnBP). Biosolids sourced from the Halifax Regional Municipality were applied at three rates on field-based lysimeter cells which were cropped to corn (Zea mays) for one growing season. In the present study, breakthrough curves (BTCs) were established for phthalates leaching from a corn-cultivated agricultural soil profile. The HYDRUS-1D model and a two-site sorption model were applied to predict transport parameters of PAEs using an inverse solution approach. Results of our research revealed that higher PAE adsorption was observed based on increasing carbon chain number. In addition, higher values of F (i.e. the fraction of type-1 sorption sites assumed to be in equilibrium with the solution phase) and lower values of D (i.e. dispersion coefficient) were observed for PAEs with large carbon chains which was validated both through the empirical dataset and the model simulations.

Evaluation of an aerobic composting process for the management of Specified Risk Materials (SRM)

In Nova Scotia (NS), approximately 2700 tonnes of Specified Risk Materials (SRM) are produced annually. SRM disposal is a serious concern for abattoirs and the beef industry. Composting offers a low risk and simple means to transform raw SRM into a more stable and easily managed material. In this project, wheat straw and sawdust were used to compost with SRM on a pilot scale. The study evaluated changes over time in total carbon, total nitrogen, pH, temperature, moisture content and electrical conductivity. Compost temperatures in all treatments met the Canadian Council of Ministers of the Environment (CCME) guidelines for pathogen kill. The compost maturity tests showed that the evolution of CO(2)-C in all the final compost products was less than 1 mg g(-1) organic matter day(-1). Wheat straw performed well as a composting feedstock for raw SRM as sawdust. While the wheat straw has advantages including greater availability, lower cost and easily decomposable carbon compounds more management is required to maintain adequate compost temperatures. The influences of seasonal variations due to temperate climatic conditions on SRM composting were also studied with wheat straw. The results suggest no significant differences in composting effectiveness between the two seasons.

Crop performance on soils receiving annual papermill biosolid amendments with and without supplementary nitrogen

Nitrogen availability is often a limiting factor for optimum crop growth on agricultural soils amended with papermill biosolids (PB). The objective of our study was to evaluate the effect on corn (Zea mays L.) and soybean (Glycine max L.) production of adding supplementary nitrogen fertilizer to soils amended with increasing rates of PB. Papermill biosolids were applied annually on four agricultural soils in southern Ontario, Canada. Treatments included three rates of PB (50, 100, and 150 Mg ha-1), combined with four levels of nitrogen fertilizer [crop recommended [CR], [CR] + 0.5 kg N Mg-1 PB, [CR] + 1.0 kg N Mg-1 PB, and [CR] + 1.5 kg N Mg-1 PB]. In addition, non-amended plots were also established receiving either (a) zero PB and zero nitrogen fertilizer or (b) zero PB and [CR] nitrogen fertilizer only. All the plots received the same treatment combinations, i.e., PB × N, each year for the duration of the study. In corn, [CR] nitrogen fertilizer was insufficient to satisfy plant growth and PB decomposi...

Effects of Temperature and Activation on Biochar Chemical Properties and Their Impact on Ammonium, Nitrate, and Phosphate Sorption

There have been limited studies of how pyrolysis temperature and activation processes alter the chemical properties of biochar and how these changes influence ammonium (NH), nitrate (NO), and phosphate (PO) sorption. This study compared the chemical properties of biochars and activated biochars (ActBC with steam and CO activation) produced by slow pyrolysis at 200 (BC200), 400 (BC400), 600 (BC600), 800 (ActBC200, ActBC400, ActBC600), and 850°C (sulfachar-S enriched biochar with steam activation). Quantitative solid-state C nuclear magnetic resonance spectroscopy and elemental analysis were used to study temperature and activation on biochar chemical properties. The sorption capacity of biochars for NH, NO, and PO were measured by batch sorption experiments. Nuclear magnetic resonance spectroscopy data showed that BC200 contained mainly aliphatic C compounds (86% of O-alkyl) belonging to cellulose and hemicellulose, whereas BC400 and BC600 composition was dominated by fused aromatic C structures, containing 81 and 97% aromatic C, respectively. Increasing pyrolysis temperatures decreased biochar total C but increased its cation exchange capacity, pH, and contents of total N and P, calcium, potassium, and magnesium. The BC200 released NO and PO, whereas sulfachar and ActBC200 sorbed significantly higher amounts NO and PO than BC600 by 83 and 96%, respectively, across aqueous solutions. Sulfachar and BC400 sorbed significantly greater amounts NH than did the other biochars. This study shows that production temperature significantly affects biochar chemical properties and that activation increases NO and PO sorption. These results suggest that activated biochar could be useful for sorbing soil N and P, thereby reducing leaching losses.