Peter Havard

Review of biosolids management options and co-incineration of a biosolid-derived fuel

This paper reviews current biosolids management options, and identifies incineration as a promising technology. Incineration is attractive both for volume reduction and energy recovery. Reported emissions from the incineration of biosolids were compared to various regulations to identify the challenges and future direction of biosolids incineration research. Most of the gaseous and metal emissions were lower than existing regulations, or could be met by existing technologies. This paper also presents the results of an experimental study to investigate the potential use of biosolids for co-incineration with wood pellets in a conventional wood pellet stove. Pilot scale combustion tests revealed that co-incineration of 10% biosolids with 90% premium grade wood pellets resulted in successful combustion without any significant degradation of efficiency and emissions.

Modeling Sediment and Nitrogen Export from a Rural Watershed in Eastern Canada Using the Soil and Water Assessment Tool

Watershed simulation models can be used to assess agricultural nonpoint-source pollution and for environmental planning and improvement projects. However, before application of any process-based watershed model, the model performance and reliability must be tested with measured data. The Soil and Water Assessment Tool version 2005 (SWAT2005) was used to model sediment and nitrogen loads from the Thomas Brook Watershed, which drains a 7.84 km rural landscape in the Annapolis Valley of Nova Scotia, Canada. The Thomas Brook SWAT model was comprised of 28 subbasins and 265 hydrologic response units, most of them containing agricultural land use, which is the main nonpoint nitrogen source in the watershed. Crop rotation schedules were incorporated into the model using field data collected within Agriculture and Agri-Food Canadas Watershed Evaluation of Beneficial Management Practices program. Model calibration (2004-2006) and validation (2007-2008) were performed on a monthly basis using continuous stream flow, sediment, and nitrogen export measurements. Model performance was evaluated using the coefficient of determination, Nash-Sutcliff efficiency (NSE), and percent bias (PBIAS) statistics. Study results show that the model performance was satisfactory (NSE > 0.4; > 0.5) for stream flow, sediment, nitrate-nitrogen, and total nitrogen simulations. Annual corn, barley, and wheat yields were also simulated well, with PBIAS values ranging from 0.3 to 7.2%. This evaluation of SWAT demonstrated that the model has the potential to be used as a decision support tool for agricultural watershed management in Nova Scotia.

Regenerative trait and cold hardiness in highly productive cultivars of alfalfa and red clover

SummaryIn earlier work on improvement of persistance in forage legumes, we selected genotypes from highly productive cultivars of alfalfa, Algonquin and Apica (Euphytica 45: 105–112, 1990) and cv. Florex red clover (Plant Cell Reports 8: 395–398, 1989) capable of in vitro regeneration from callus and cell culture. The alfalfa germplasm and its F1 progeny as well as an F2 red clover population were tested for cold stress tolerance. Plantlets were hardened in culture tubes at 2 or 5°C, 8h photoperiod, for at least four weeks and then subjected to freezing temperatures, −16 or −10°C for alfalfa and red clover, respectively. Survival of regenerative genotypes was significantly higher than of the non-regenerative ones in both species. A strong oositive correlation (r=0.78) between the regenerative trait and plant survival was found in alfalfa. The experiments indicate that in vitro selection for regenerative trait may improve cold stress tolerance of alfalfa and red clover.

Effects of Hydraulic Loading Rate and Filter Length on the Performance of Lateral Flow Sand Filters for On-Site Wastewater Treatment

On-site treatment of residential wastewater is important for rural and remote regions where centralized wastewater treatment may not be feasible. Sand filtration is a proven method for secondary treatment of septic tank effluent (STE) and can be an economical option where soil conditions do not favor the installation of a typical disposal field. This study investigates the hydraulics and treatment performance of eight lateral flow sand filters (LFSFs) receiving domestic STE at the Bio-Environmental Engineering Centre (BEEC) in Truro, Nova Scotia, Canada. The main objectives of this study were to evaluate the long-term treatment performance associated with the LFSFs and to investigate the effects of filter length and wastewater loading on performance. Previous research conducted at the BEEC indicated that current technical guidelines used in Nova Scotia for the design of LFSFs may be conservative and that the design of these systems could be optimized. The hydraulics and treatment performance associated wi...

Co-liquefaction of spent coffee grounds and lignocellulosic feedstocks

Co-liquefaction of spent coffee grounds (SCG) with paper filter (PF), corn stalk (CS) and white pine bark (WPB) respectively, was examined in subcritical water for bio-crude oil production. The optimum reaction temperature was 250°C, and the mixing biomass ratio was 1:1. SCG and CS was identified to be the best feedstock combination with a significant positive synergetic effect in the co-liquefaction process with 5% NaOH as a catalyst. The yield of bio-crude oil was increased by 20.9% compared to the mass averaged yield from two feedstocks, and the oil quality was also improved in terms of viscosity and relative molecular mass. A negative effect presented in the co-liquefaction of SCG/WPB. The resulting bio-crude oils were characterized by elemental analyzer, GC-MS, GPC and viscometer, indicating that mixing feedstock in the co-liquefaction process also influenced the higher heating value (HHV), viscosity, molecular mass and chemical composition of bio-crude oil.

Electromagnetic Induction Methods for Water Management Enhancement

Electromagnetic induction (EMI) methods are gaining popularity due to their non-destructive nature, rapid response and ease of integration into mobile platforms. Observation wells, of 2.5m length x 0.05 m diameter were installed to calibrate the DualEM for predicting the groundwater depths within a field in central Nova Scotia. The user interface program was developed in Delphi 5.0 software to store the data from sensor and differential global positioning system (DGPS). The regression model showed significant correlation between the actual groundwater table depths and ground conductivity measured with DualEM with co-efficient of determination (R2 = 0.88; n=15, p<0.01). Surveys were conducted using DualEM and DGPS to map ground conductivity in selected field. The predicted groundwater table maps were generated in ArcView 2.3 GIS software. This information could be used for scheduling irrigation and designing drainage systems within fields.

An Initial Assessment of a Wetland-Reservoir Drainage Water Treatment and Reuse System in Nova Scotia

Nutrient and pathogen export from agricultural drainage water is a major source of surface water quality degradation. Wetland-reservoir drainage water treatment and reuse systems have the potential to mitigate this pollution, as well as conserve water, improve crop yields, and increase bio-diversity. This study will assess the viability of this type of system in a colder climate. Specific objectives are to assess (i) system hydraulics and water balances; (ii) wetland treatment efficiencies; and (iii) reservoir water quality.

Development and Performance Testing of a Light Source System on a Smart Sprayer for Spot-Application of Agrochemical in Wild Blueberry Fields

Abstract. Wild blueberry producers occasionally are required to apply agrochemicals during the early morning, evening or after dark with low wind conditions. The objective of this study was to develop an artificial light source system that could be added to a smart sprayer to allow cameras to detect target areas in the field with low ambient light conditions. The design requirements were a rugged construction that gave an even light distribution under an entire 12.2 m machine vision sensor boom. Polystyrene diffuser sheets were used to eliminate the hot spots created by the lights. A lux light meter was used to determine the light intensity at 0.3 m spacing on the ground under the camera boom with zero ambient light. A field test was completed in a wild blueberry field in central Nova Scotia, Canada to test the developed light source system with low natural light conditions. A real-time kinematics-global positioning system was used to map the boundary of the test track, selected bare soil areas, weed areas and wild blueberry plant areas in the field. The smart sprayer and light source system was driven across the test track several times using different combinations of camera and image processing settings to determine the optimum values for use with the developed light source. Spray percent area coverage on water sensitive papers placed in bare soil and blueberry patches were 22.34% and 25.79% lower than in weed patches, respectively. Spray savings of 65% was obtained using the smart sprayer for spot-application on weeds.