Browsing by Author "Hettiaratchi, J. P. A."

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Application of Aerobic Granular Sludge (AGS) Technology for the Treatment of Pulp Mill Effluent
    (2019-04-30) Vashi, Harsh; Tay, Joo Hwa‏; Bergerson, Joule; Hettiaratchi, J. P. A.
    The pulp and paper industry produces a significant amount of wastewater with toxic and recalcitrant compounds. Pulp and paper wastewater (PPW) requires a special treatment method that is diverse enough to deal with the complexities of this type of wastewater. The present study was aimed primarily at the removal of tannin/lignin from PPW using aerobic granular sludge (AGS) technology. Aerobic granules were cultivated in a sequencing batch reactor (SBR) with tannin/lignin present in the range of 50-200 mg/L. Granules were cultivated within 9 days of operation of the sequencing batch reactor (SBR), with SVI30 of 51.6 mL/g, achieving steady-state within the first three weeks of operation. On average, the COD removal efficiency for synthetic PPW was 90%. Tannin/lignin were removed up to 80% during the initial stages, but slowly decreased to an average removal of 70%. The mature granules were then transferred to a real PPW wastewater system containing tannin/lignin concentration up to 500 mg/L. Biodegradation and biosorption were observed to be the two pathways for the removal tannin/lignin. Biosorption was a primary form of removal at lower concentrations, achieving 74% removal at 50 mg/L. The biosorption ability reduced to 58% removal at 200 mg/L. This reveals that biodegradation prevails at these higher concentrations. The Haldane kinetic parameters were: Vmax = 0.93 (g tannin/lignin/g VSS· day), Ks = 1910 mg/L, and Ki = 27 mg/L. Various adsorption kinetic models and isotherms were fitted to the system. The Langmuir isotherm coefficients were: (x/m) max = 21.5 (mg tannin/lignin/g SS), b = 0.00386 L/mg. The Freundlich isotherm had coefficients of n = 1.172, K = 0.1174. COD removal of 79% and a tannin/lignin removal of 56% were achieved with real PPW. Furthermore, experimental runs in warmer and more humid temperature conditions revealed higher removal efficiencies, achieving about 80% tannin/lignin degradation at a concentration of 130 mg/L. The most prominent species responsible for the degradation of these toxic substances were Pseudomonas, Corynebacteriaceae and Flavobacterium.
  • Thumbnail Image
    ItemOpen Access
    Development of a Landfill Model to Prioritize Design and Operating Objectives
    (Springer, 2007) Ohman, K. V. H.; Hettiaratchi, J. P. A.; Ruwanpura, J.; Balakrishnan, Jaydeep; Achari, G.
  • Thumbnail Image
    ItemOpen Access
    A Framework for Enhancing Engineering Deliverables to Improve Construction Performance in Oil and Gas Projects
    (2018-12-20) Gholami Bavil Olyai, Farshid; Jergeas, George Farage‏; Jugdev, Kam; Dann, Markus R.; Hettiaratchi, J. P. A.; Ruwanpura, Janaka Y.
    Alberta’s oil industry is one of the largest constituents of Canada’s economy, and will remain a key determinant of the nation’s economic growth for the foreseeable future. Existing research conducted on the performance of Alberta’s oil industry capital projects reveals that construction cost overruns and schedule delays are among the leading contributors to capital expenditure in oil and gas projects. The significance of project cost and schedule growth has motivated industry and academia to initiate a great amount of research identifying the factors affecting construction performance in oil and gas construction projects. Problems in the project engineering phase, along with many other factors, have been identified as a root cause leading to cost and schedule slippage in construction within oil and gas projects. The current study aims at bridging the existing knowledge gap of: (a) what factors in engineering deliverables are actually contributing to poor cost and schedule performance, and (b) how those factors can be mitigated during the process of projects. This research has been conducted in two phases to address those objectives. A quantitative research approach was adopted in the first phase to detect the issues in engineering deliverables, and a qualitative method was used in the second phase to identify the root causes that contribute to those issues, and the measures to mitigate them. In the first phase, the research data were collected through a questionnaire survey, and were quantitatively analysed to rank the identified issues by their impact on construction performance. In the second phase, interviewing was the main instrument for collection of data, which were then analysed using qualitative research techniques. Three major groups of issues were identified as the top-rank contributors to poor construction performance: engineering design issues, engineering schedule issues, and design changes after IFC (Issued for Construction) revision. The qualitative study in the second phase of the research revealed communications as the root of what needs to be improved to enhance engineering deliverables. Built on the foundations of the findings in the two phases of the research, a framework was developed for enhancing engineering deliverables to improve construction performance. The outcomes of this study can be used by oil industry project officials at different levels, to prevent construction cost and schedule growth, through implementing the findings of the research in project process, procedures, and other activities.