Angus Chu

Finding Knowledge Gaps in Aerobic Granulation Technology

This review identifies the knowledge gaps in aerobic granulation technology and defines some problems for future studies. In particular, extracellular polymeric substances (EPSs) should be further characterized to understand the intermolecular interactions among these polymers, the role of chelating agents in destabilizing EPS ionic bridges needs further elucidation, and early detection of the quorum-quenching enzymes should be considered to avoid granule segregation and process failure. Furthermore, the process should be supplemented with volatile fatty acids as electron donors/carbon sources, and appropriate anoxic/anaerobic conditions should be provided for enhanced nitrogen and phosphorus removal. Finally, the biodegradation, bioaccumulation, biosorption, and mass transfer behaviors of the emerging contaminants within the granules need further investigation.

Anaerobic digestion of specified risk materials with cattle manure for biogas production.

Biogas production from anaerobic digestion (AD) of specified risk materials (SRM) co-digested with cattle manure was assessed in a 3 x 2 factorial design. SRM replaced manure at 0 (control), 10% or 25% (w/w) as the substrate fed to six 2-L biodigesters maintained at 37 degrees C or 55 degrees C. Digesters were fed substrate (30 g L(-1) total volatile solids) at 6-d intervals for 90 d, with a retention time of 30 d. Keratin (<20mg) was added to each digester to model the degradation of beta-sheet rich proteins. Methane production was measured daily, and effluent was collected at feeding to monitor SRM degradation using real-time PCR analysis of bovine-specific DNA fragments. Compared with control, methane production increased by 83% or 161% (P<0.05) with 10% or 25% SRM at 37 degrees C, and by 45% and 87%, respectively, at 55 degrees C (P<0.05). Bovine DNA degradation over 6d was higher (P<0.05) at 37 degrees C as compared to 55 degrees C. Dry matter degradation of keratin at 37 degrees C decreased with increasing SRM concentration (P<0.05), whereas at 55 degrees C no difference between treatments was observed (P>0.05). Inclusion of SRM increases the production of methane during the anaerobic digestion of manure and may offer a means of deriving economic value from the disposal of SRM.

Leachability and Toxicity of Hydrocarbons, Metals and Salt Contamination from Flare Pit Soil

Although composite chemical analyses, such as total petroleumhydrocarbons and total metals, are often used to assess theextent of contamination at an industrial site, it is difficultto relate chemical analyses to the environmental andtoxicological effects of soil contamination. Since toxicity isrelated to contaminant bioavailability and solubility,identification and quantification of leachable contaminantsshould provide an indication of the environmental hazard of the site contaminants. Experiments were performed to determine theleachability and toxicity of contaminants from a flare pit soilwhich was extensively contaminated with hydrocarbons, metals andsalt. Toxicity bioassays included earthworm mortality(Lumbricus terrestris), seed germination and root elongation(Lactuca sativa and Panicum miliaceum L.),algal growth inhibition (Selenastrum capricornutum) andbacterial luminescence inhibition (Pseudomonasfluorescens). Although this soil would require remediationaccording to chemically based soil criteria, neither the contaminated soil nor leachate generated from the contaminated soil were particularly toxic.

Determination of ethanolamine, ethylene glycol and triethylene glycol by ion chromatography for laboratory and field biodegradation studies.

The determination of alkanolamines and glycols in groundwater and subsurface environments is essential for environmental assessment, remediation and monitoring for selected industrial sites. Monoethanolamine (MEA), ammonium, sodium, magnesium and calcium detection was performed using cation exchange chromatography (IC) with suppressed conductivity detection. Acetate, chloride, nitrite, nitrate, phosphate, sulfate and oxalate were monitored employing anion exchange chromatography with suppressed conductivity. Detection of ethylene glycol (MEG) and triethylene glycol (TEG) and ethanol was carried out using ion exclusion chromatography with pulsed amperometric detection. Effective determination of MEA, MEG and TEG in complex groundwater matrices without compound transformation offered improved monitoring capabilities. This study presents robust analytical tools for MEA, MEG and TEG determination in biodegradation studies. Using ion chromatography offered significant advantages for the analyses of groundwater samples and laboratory bioreactor monitoring.

Characterizing Physicochemical Quality of Storm-Water Runoff from an Urban Area in Calgary, Alberta

Understanding storm-water runoff quality is required to develop effective urban storm-water runoff management for regions of semiarid climate. In this study, the quality of storm-water runoff from a semiarid, urban residential catchment, draining through separated storm-water sewers was investigated in 2006 and 2007. Water temperature, conductivity, pH, dissolved oxygen, and turbidity were continuously measured during 16 storm events. Storm-water runoff quality was characterized in terms of event mean values (EMVs), loads, and first flush (FF) loads and their relationships with rainfall characteristics. Discharge of total suspended solids (TSSs) is in general governed by the flow magnitude in storms and no significant relationships exist between the FF loads of TSS and rainfall intensity. The discharge of dissolved solids is independent of the flow magnitude. Strong FF effect for dissolved solids and weak FF effect for TSS were observed. This semiarid region provided no relationship between the EMVs of both TSS and conductivity and the antecedent dry period. This raises doubts on storm-water runoff being more heavily loaded with pollutants after a longer dry period in semiarid regions.

Characteristics of suspended solids, microorganisms, and chemical water quality in event-based stormwater runoff from an urban residential area.

Temporal evolution of microbiological, physical, and chemical quality of stormwater runoff from a stormwater drain in an urban residential area in Calgary, Canada, was investigated from May to September, 2006 and 2007. Investigating event mean concentrations and their correlations with rainfall characteristics revealed that intensive rainfall events produced highly polluted stormwater runoff when pollutant source limitation did not occur. Inconsistent event-based correlations between total suspended solids (TSS) concentrations and water quality parameters were observed. During storms, the loading of TSS exhibited a flow-dependent nature, whereas microorganism discharge appeared to be governed by a flow-independent mechanism. No strong first-flush effect was observed in either TSS or microorganisms, on average. No correlations of first-flush loads of TSS with rainfall characteristics were identified. Moderate negative correlations between first-flush loads of microorganisms and rainfall depth and intensity indicated that first flush of microorganisms tended to occur in small storms.

The effects of macromolecular substrates and a metabolic inhibitor on volatile fatty acid metabolism in thermophilic aerobic digestion

The effects of spiking macromolecular substrates and an inhibitor on the metabolic behavioral patterns of thermophilic aerobic digestion (TAD) biomass, from a pilot scale system, were studied. The 3 macromolecules examined were linoleic acid (lipid), peptone (protein) and dextrin (carbohydrates). Linoleic acid did very little in terms of volatile fatty acid (VFA) stimulation in either anaerobic or microaerobic environments. Dextrin stimulated propionate and acetate production in a rough 2 propionate to 1 acetate molar ratio under anaerobic conditions. Peptone was the only one of the three tested substrates that stimulated only acetate production under fermentative conditions. Under microaerobic conditions (oxygen demand exceeds oxygen supply), both peptone and dextrin stimulated the production of acetate. The results seen under both anaerobic and microaerobic experimental conditions, with the exception of linoleic acid, in so far as redox balance is concerned, are consistent with the hypothesized biochemical mechanisms describing substrate metabolism in TAD proposed by Chu et al . (1996). Since fermentative reactions do not utilize oxidative phosphorylation to produce energy, 2,4-dinitrophenol had no measurable effect on VFA metabolism in an anaerobic environment. The effect of this agent under microaerobic conditions, was to induce the process biomass to switch from generating energy via oxidative means to using substrate level phosphorylation reactions. This results in the accumulation of large amounts of acetate in excess of the control condition that was not treated with 2,4-dinitrophenol, since acetate production from acetyl-Coenzyme A yields energy.

Three Types of Permeable Pavements in Cold Climates: Hydraulic and Environmental Performance

AbstractThis paper examined and compared the hydraulic and environmental performance of permeable interlocking pavers (PICPs), porous asphalt (PA), and porous concrete (PC) under cold climate conditions in Calgary, Alberta, Canada. Assessments were made of their hydraulic performance in terms of storm runoff reduction and surface infiltration capacity, and environmental performance in terms of the removal of several pollutants including total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP) and, heavy metals: copper (Cu), lead (Pb), and zinc (Zn). Results from this paper demonstrated that PA, PC, and PICPs are all effective in mitigating storm runoff under cold climate conditions. Surface infiltration rate was substantially affected by winter sanding materials for PA, PC, and PICPs. Pressure washing was demonstrated to be able to partially restore surface infiltration rates for all three types of pavements. All pavement types in general have the same level of performance in removing TSS...

Response of green roof performance to multiple hydrologic and design variables: a laboratory investigation

Multiple factors affect green roof performance and their effects might vary at different stages of operation. This paper aimed to link green roof performance to hydrologic variables (antecedent moisture condition (AMC) and rainfall intensity) and design variables (growing medium (GM) type and depth) under multiple dimensions at the early stage of operation using laboratory experiment data. The results showed that the AMC is the most influential factor of hydrologic performance, whereas the GM type appeared to primarily affect the nutrient levels of the outflow. The significant main effects of other variables and interaction effects between two variables point to challenges in green roof design.

Bioenergy feasibility study of a raw corn and peas processing facility in Lethbridge, Alberta

ABSTRACT A bioenergy feasibility study was conducted for Canada Safeway on their Lucerne vegetable processing plant located in Lethbridge, Alberta. An energy load profile for the plant was estimated using utility records from the years 2005 to 2007, inclusive. Organic load was calculated from the wastewater utility records for the same period. The study used a common energy unit (the kilowatt, kW) to compare plant energy load with a theoretical biogas yield, and proposes a bioenergy system. Based on two existing cogeneration plants of similar size located in Alberta, a system size of 800 to 1000 kW is proposed. The proposed system assumes wastewater ‘peak shaving’ and the establishment of ‘feedstock co-digestion’. An estimated cost for the facility is CCanadian Dollar (AD) 7M to CAD 8M (2002 dollars), with an assumed return on investment of 8 to 9 years.