Panagiotis Elefsiniotis

University of Auckland, Auckland, Auckland, New Zealand

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Publications (35)37.85 Total impact

  • Aparajita Boyle-Gotla, Panagiotis Elefsiniotis
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    ABSTRACT: This study addressed the removal of ammonia from recycled centrate via biological nitrification and denitrification in batch reactors. Nitrification was successful at ammonia feed concentrations up to 400 mg/L and carbon-to-nitrogen (C/N) ratios greater than 1. The use of pre-exposed biomass to ammonia-rich centrate reduced considerably the overall time required for nitrification, which was also reflected on the corresponding specific rates. The denitrification of naturally-generated nitrates proceeded smoothly, with methanol modestly outperforming acetate as external carbon source. Furthermore, simultaneous nitrification and denitrification (SND) was induced in the presence of readily biodegradable organic carbon (i.e., methanol or acetate) under aerobic conditions. Overall, total nitrogen removal from ammonia-rich centrate by biological methods was viable under the conditions investigated.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 01/2013; 48(3):331-7.
  • Prayoon Fongsatitkul, Panagiotis Elefsiniotis, David G Wareham
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    ABSTRACT: Energy generation from methane (CH(4)) is one of the primary targets of the anaerobic digestion process. Consequently, the focus of this study was to investigate the effect on CH(4) production of total solids (TS) loading (measured as % TS) and hydraulic residence time (HRT) during the treatment of the organic fraction of municipal solid waste (OFMSW). Laboratory-scale, two-phase anaerobic digestion systems were employed with each system consisting of an acidogenic reactor and a methanogenic reactor linked in series. The group A runs in the experiment explored the effect on digester performance of four variations in methanogenic HRT (15, 20, 25 and 30 days) at three different feed TS concentrations (8, 12 and 15%). The group B runs compared the actual methane yield (0.14 to 0.45 L g VSfeed−1)) to that predicted by the Chen-Hashimoto model. Results from the group A runs indicated that acidogenesis improved with an increase in % TS and a decrease in HRT; while, methanogenesis behaved inversely, achieving higher yields at the lower % TS and longer HRT values. In comparison with the group B runs, the Chen-Hashimoto model under-predicted (by an average of 16.5 ± 6.6%) the CH(4) yield obtained from the digestion of OFMSW.
    Waste management & research : the journal of the International Solid Wastes and Public Cleansing Association, ISWA. 01/2012; 30(7):720-6.
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    ABSTRACT: This study investigated the ability of an anaerobic/anoxic/oxic (A2/O) system to treat a slaughterhouse wastewater. The system employed two identical continuous-flow reactors (101 total liquid volume each) running in parallel with the main operational variable, being the internal recycle (IR) rate. The chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) performance was evaluated as the IR flowrate was increased from a Q of 151d(-1) to 4Q at a system hydraulic retention time of 16 h and a solids retention time of 10 d. The COD:TKN and COD:TP ratios were 8.2:1 and 54:1, which supported both nitrogen and phosphorus removal. For all IR multiples of Q, the COD removal was in excess of 90%. The TKN removal showed a modest improvement (a 4-5% increase, depending on the dissolved oxygen (DO)) as the IR doubled from Q to 2Q, but no further increase was observed at the 4Q IR rate. The TP removal reached its optimum (around 85%-89% (again depending on the DO)) at the 2Q rate.
    Environmental Technology 12/2011; 33(15-16):1755-9. · 1.61 Impact Factor
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    ABSTRACT: This laboratory-scale study explored the use of rice husk ash (RHA) as an admixture to stabilize and solidify the waste sludge from a chrome-tanning process. Various ratios of RHA and tannery sludge were used, ranging from 0.25 to 1.0 by weight of the cement content, resulting in an experimental matrix of 16 runs. It was observed that although the compressive strength of solidified sludge improved at longer curing times, the increase was moderate after 7days of curing. In addition, higher RHA and/or sludge ratios progressively reduced the strength of the samples. On the other hand, curing time had a positive effect on chromium leachability since the leaching concentration decreased considerably with an increase in curing time, up to 28days. Furthermore, both the RHA and/or sludge content affected leachability, producing acceptable results, from a Thai regulatory perspective, at ratios of 0.50 or lower. Finally, the solidified sludge can be disposed of in a secure landfill and/or used as a construction material in a number of applications. KeywordsChromium removal–Tannery waste sludge–Rice husk ash–Stabilization/solidification
    Water Air and Soil Pollution 01/2011; 220(1):81-88. · 1.75 Impact Factor
  • Prayoon Fongsatitkul, Panagiotis Elefsiniotis, David G Wareham
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    ABSTRACT: This paper describes how the degradation of the organic fraction of municipal solid waste (OFMSW) is affected through codigestion with varying amounts of return activated sludge (RAS). Solid waste that had its inorganic fraction selectively removed was mixed with RAS in ratios of 100% OFMSW, 50% OFMSW/50% RAS, and 25% OFMSW/75% RAS. The total solids (TS) concentration was held at 8% and three anaerobic digester systems treating the mixtures were held (for the first run) at a total hydraulic retention time (HRT) of 28 days. Increasing amounts of RAS did not however improve the mixture's digestability, as indicated by little change and/or a drop in the main performance indices [including percentage volatile solids (VS) removal and specific gas production]. The optimum ratio in this research therefore appeared to be 100% OFMSW with an associated 85.1 ± 0.6% VS removal and 0.72 ± 0.01 L total gas g(- 1) VS. In the second run, the effect of increasing percentage of TS (8, 12% and 15%) at a system HRT of 28 days was observed to yield no improvement in the main performance indices (i.e. percentage VS removal and specific gas production). Finally, during the third run, variations in the total system HRT were investigated at an 8% TS, again using 100% OFMSW. Of the HRTs explored (23, 28 and 33 days), the longest HRT yielded the best performance overall, particularly in terms of specific gas production (0.77 ± 0.01 L total gas g(-1) VS).
    Waste management & research : the journal of the International Solid Wastes and Public Cleansing Association, ISWA. 02/2010; 28(9):811-7.
  • Mohammad A Rahman, Panagiotis Elefsiniotis
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    ABSTRACT: This study investigated the effect of upper mesophilic temperature and feed-to-seed (F/S) ratio on anaerobic digestion using four 3.5 L batch-scale reactors. Initially, eight F/S ratios, ranging from 10/90 to 90/10, were explored at 37 degrees C, using a mixture of primary and secondary municipal sludge as feed. It was observed that the systems with low F/S ratios (40/60 and below) showed a stable performance while those with high ratios (50/50 and above) experienced the effect of organic overloading indicated by reduced removal of volatile solids (VS) in the feed, a drop in pH, volatile fatty acid (VFA) accumulation during the first 10 days of operation, and total gas production markedly lower than the corresponding theoretical values. Subsequently, the effect of temperature, in the 37 to 49 degrees C range, was studied at an F/S ratio of 20/80. Results revealed that an increase in temperature between 37 and 43 degrees C had a rather minimal effect on the process, with the exception of a moderate increase in total gas production. A further rise in the temperature in the 45 to 49 degrees C range however appeared to trigger an adverse effect evidenced by enhanced percent VSS reduction (possibly the result of cell lysis), VFA accumulation and an increase in the non-VFA total organic carbon (TOC) content. Therefore, it can be concluded that an operating temperature in the 37 to 43 degrees C range resulted in a stable and satisfactory reactor performance.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 01/2010; 45(9):1126-33.
  • D F Shams, N Singhal, P Elefsiniotis, A Johnson
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    ABSTRACT: Biological removal of nitrogen and carbon from farm dairy effluent (FDE) was studied with two laboratory-scale systems following nitrification and denitrification processes. Each system consisted of an upflow multilayer bioreactor (UMBR) as a pre-denitrification unit, an aeration tank (AT) as nitrification unit and a secondary clarifier. The optimization of two operational variables, total hydraulic retention time (HRT) and internal recycle (IR) rate with both real-FDE and a synthetic-wastewater were investigated. First, HRTs of 2, 3, 4 and 5 days were tested with synthetic-wastewater at uniform IR rate. The HRT of 4 days proved optimum with high efficiencies for nitrification (>90%), denitrification (>90%) and total chemical oxygen demand (COD) removal ( approximately 90%). The lowest efficiency was recorded at 2 days HRT with 7% nitrification efficiency. This was followed by experimentation with IR rates of 200%, 300% and 400% on both real-FDE and synthetic-wastewater at optimized HRT. The increase in IR to 300% improved the denitrification potential and overall performance with continuous high nitrification efficiency and COD removal whereas IR of 400% retarded the process. The application of combined UMBR and activated sludge system showed good potential for biological removal of nitrogen from FDE.
    Water Science & Technology 01/2010; 61(7):1683-90. · 1.10 Impact Factor
  • Y S Tam, P Elefsiniotis
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    ABSTRACT: This study explored the potential of lead and copper leaching from brass plumbing in the Auckland region of New Zealand. A five-month field investigation, at six representative locations, indicated that Auckland's water can be characterized as soft and potentially corrosive, having low alkalinity and hardness levels and a moderately alkaline pH. More than 90% of the unflushed samples contained lead above the maximum acceptable value (MAV) of 10 microg/L (New Zealand Standards). In contrast, the copper level of unflushed samples remained consistently below the corresponding MAV of 2 mg/L. Flushing however reduced sharply metal concentrations, with lead values well below the MAV limit. Generally, metal leaching patterns showed a limited degree of correlation with the variations in temperature, dissolved oxygen and free chlorine residual at all sampling locations. Furthermore, a series of bench-scale experiments was conducted to evaluate the effectiveness of pH and alkalinity adjustment, as well as orthophosphate addition as corrosion control tools regarding lead and copper dissolution. Results demonstrated that lead and copper leaching was predominant during the first 24 hr of stagnation, but reached an equilibrium state afterwards. Since the soluble fraction of both metals was small (12% for lead, 29% for copper), it is apparent that the non-soluble compounds play a predominant role in the dissolution process. The degree of leaching however was largely affected by the variations in pH and alkalinity. At pH around neutrality, an increase in alkalinity promoted metal dissolution, while at pH 9.0 the effect of alkalinity on leaching was marginal. Lastly, addition of orthophosphate as a corrosion inhibitor was more effective at pH 7.5 or higher, resulting in approximately 70% reduction in both lead and copper concentrations.
    Journal of Environmental Science and Health Part A 10/2009; 44(12):1251-60. · 1.25 Impact Factor
  • P. Elefsiniotis, E. R. Hall, R. M. Johnson
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    ABSTRACT: This study investigated the potential of ultrafiltration technology and/or biological treatment to remove contaminants such as total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), and resin and fatty acids (RFAs) from recirculated white water. Batch ultrafiltration experiments indicated that TDS, soluble COD, and TOC removal efficiencies were affected by membrane molecular weight (molar mass) cut-off, but were independent of the operating temperature, in the 20 to 60°C range. Except for fatty acids, where average removals exceeded 90%, the separation efficiency of the process for all other parameters (TDS, soluble COD, TOC, and resin acids) was moderate, ranging from 10 to 41%. Biological treatment using a sequencing batch reactor (SBR) unit was very effective in removing RFAs, TOC, total and soluble COD. Furthermore, ultrafiltration of the biologically treated process water resulted in significant additional TDS, soluble COD, and TOC removal.On évalue dans cette étude le potentiel de la technologie d'ultrafiltration et du traitement biologique pour retirer de l'eau blanche en recirculation des contaminants tels que la quantité totale de matières dissoutes (TDS), la demande chimique en oxygène (COD), le carbone organique total (TOC) et les acides gras et résineux (RFA). Des expériences d'ultrafiltration discontinues indiquent que les efficacités de retrait de TDS, COD soluble et TOC sont influencées par la coupure du poids moléculaire des membranes (masse molaire), mais qu'elles sont indépendantes de la température de fonctionnement, dans la gamme de 20 à 60°C. Sauf pour les acides gras, pour lesquels les retraits moyens excèdent 90%, l'efficacité de séparation du procédé pour tous les autres paramètres (TDS, COD soluble, TOC et acides résineux) est moyenne, allant de 10 à 41%. Le traitement biologique avec un réacteur discontinu séquence (SBR) s'est avéré très efficace pour le retrait des RFA, du TOC et de la COD totale et soluble. En outre, l'ultrafiltration de l'eau de procédé traitée biologiquement a permis un retrait supplémentaire significatif de la TDS, de la COD soluble et du TOC.
    The Canadian Journal of Chemical Engineering 03/2009; 75(1):88 - 94. · 1.00 Impact Factor
  • David G. Wareham, Panagiotis Elefsiniotis
    Environmental Engineering Science - ENVIRON ENG SCI. 01/2009; 26(3):673-678.
  • P Fongsatitkul, D G Wareham, P Elefsiniotis
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    ABSTRACT: This study investigated the ability of a sequencing batch reactor (SBR) system to treat four industrial wastewaters, namely, textile, landfill leachate, seafood and slaughterhouse effluents. The system employed three identical SBRs (10 l volume each) operating in parallel and each waste was treated one at a time. The operational variables examined included the length of the non-aerated period and the solids retention time (SRT). All four wastewaters experienced chemical oxyfen demand (COD) and total kjeldhal nitrogen (TKN) removals greater than 81%, while the TP removals were lower, ranging from 57 to 94%. The length of the non-aerated period appeared to have minimal effect on the SBR performance; however, increases in SRT reduced the percent TP removal for the textile and leachate wastes only. In addition, to investigate organic loading limits to the seafood SBR system, the COD was increased by three increments of 250 mg l(-1) starting from a baseline concentration of 1100 mg l(-1). This resulted in a reduction in both the TKN and TP removal at the higher concentrations. Finally, for the slaughterhouse wastewater, the COD:TKN ratio was tested at levels of 6:1, 8:1 and 9:1 with the result that only the TP removal was affected at the lowest ratio.
    Environmental Technology 12/2008; 29(11):1257-64. · 1.61 Impact Factor
  • E Celis, P Elefsiniotis, N Singhal
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    ABSTRACT: This study investigated the biodegradability of the herbicides isoproturon and 2,4-dichlorophenoxyacetic acid (2,4-D) in sequencing batch reactors (SBRs). Two laboratory-scale (2L liquid volume) SBRs were employed: one reactor performing under aerobic and the other under anaerobic conditions. The aerobic SBR was operated at an ambient temperature (22+/-2 degrees C), while the anaerobic SBR was run in the lower mesophilic range (30+/-2 degrees C). Each bioreactor was seeded with a 3:1 mixture (by weight) of fresh sludge and biomass that had been previously exposed to both herbicides. The effect of herbicide concentration on either treatment process was explored at a hydraulic retention time (HRT) of 48 h, using glucose as a supplemental carbon substrate. Although no isoproturon degradation was observed in either system during the study, complete 2,4-D removal occurred after an acclimation period of approximately 30 d (aerobic SBR) and 70 d (anaerobic SBR). The aerobic reactor achieved complete 2,4-D utilization at feed concentrations up to 500 mg/L. A further increase to 700 mg/L, however, proved to be inhibitory since 2,4-D biodegradation was negligible. On the other hand, the anaerobic SBR was able to degrade 120 mg/L of 2,4-D, which corresponds to 40% of the maximum feed concentration applied. Moreover, glucose was consumed first throughout the experiment in a sequential utilization pattern relating to 2,4-D, with biodegradation of both substrates following closely first-order kinetics.
    Water Research 07/2008; 42(12):3218-24. · 4.66 Impact Factor
  • P Fongsatitkul, D G Wareham, P Elefsiniotis
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    ABSTRACT: In this study, 10 L sequencing batch reactors (SBRs) were operated at a 12-h cycle length (four alternating anoxic/oxic conditions) to assess the biological nutrient removal potential of a domestic wastewater treated at the Huay Kwang plant, Bangkok, Thailand. The wastewater was found to be carbon-limited (chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) (i.e., COD:TKN) ratio of 6.4:1). This ratio was insufficient to support good phosphorus removal. Glucose was therefore added to increase the COD:TKN ratio ultimately to 10:1 and the COD, TKN and total phosphorus (TP) removals at this ratio were all in excess of 95%. An alternative carbon source from a local fruit canning industry was then added at the same COD:TKN ratio; and, in order to increase the throughput of the waste treated, the cycle length was simultaneously shortened to 8 h keeping approximately the same anoxic/oxic fractions. The COD removal remained high (> 95%), however the TKN and TP removals were substantially reduced (79% and 66%, respectively), indicating that the shortened cycle length was sub-optimum. The last phase of the research involved changing the anoxic/oxic fractions of the cycle time to maximize performance. It was found that for the conditions studied in this research, the performance improved in proportion to the increase in the first anoxic fraction, being most stable at the highest anoxic fraction of the cycle length (0.33).
    Journal of Environmental Science and Health Part A 07/2008; 43(7):725-30. · 1.25 Impact Factor
  • Panagiotis Elefsiniotis, Wei Li
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    ABSTRACT: This study explored the biodegradation potential of two agricultural pesticides (2,4-D and isoproturon) as well as their effect on the performance of the anaerobic digestion process. Three 3.5 L batch reactors were used, having the same initial isoproturon concentration (25 mg/L) and different 2,4-D concentrations (i.e. 0, 100, or 300 mg/L, respectively). All systems were fed with equal amounts of primary sludge and digested sludge and operated at the low mesophilic range (32 +/- 2 degrees C). Following an acclimation period of approximately 30 days, complete 2,4-D removal was achieved, whereas isoproturon biodegradation was practically negligible. The presence of 2,4-D did not have a direct effect on acidogenesis since soluble organic carbon [expressed either as volatile fatty acids (VFAs) or as total organic carbon (TOC)] peaked within the first 10 days of operation in all bioreactors. Utilization of VFAs however appeared to follow two distinct patterns: one pattern was represented by acetate and butyrate (i.e. no acid accumulation) while the other was followed by propionate, isobuturate, valerate and isovalerate (i.e. acid accumulation, duration of which was related to the initial 2,4-D concentration). On the whole, all reactors exhibited a successful digestion performance demonstrated by complete VFAs utilization, considerable gas production (containing 45 to 65% methane by volume), substantial volatile suspended solids (VSS) reduction (42 to 50%), as well as pH and alkalinity recovery.
    Journal of Environmental Science and Health Part B 03/2008; 43(2):172-8. · 1.21 Impact Factor
  • P. Elefsiniotis, D.G. Wareham
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    ABSTRACT: This research investigated the utilization pattern of volatile fatty acids (VFAs) in the denitrification process. To be thorough, both synthetically produced and naturally generated VFAs were considered with the synthetic compounds being acetate, propionate and a mixture of these acids. The natural VFAs (acetate, propionate, butyrate and valerate) were produced from a laboratory-scale, completely mixed anaerobic digester. The wastewater used was a 1:1 mixture of municipal sludge and a potato-processing wastewater diluted to 5000 mg L−1 of total solids (TS). Steady-state, acidogenic conditions produced net VFAs of approximately 780 mg L−1. In addition, 36 denitrification experiments were conducted in 0.6 L batch reactors (18 using natural VFAs (the N-series) and 18 using synthetic VFAs (the S-series)). Nitrates completely disappeared and the average specific denitrification rate (kN) for the N-series (0.0111 g NO3−-N g VSS−1 d−1) was close to the mixture of the S-series (0.0134 g NO3−-N g VSS−1 d−1). Within the S-series, the kN value for acetate was more than double that of propionate reflecting a preference for acetate. The average specific carbon consumption rate (kC) for the N-series (0.0252 g VFA-C g VSS−1 d−1) was similar to the kC for the S-series (0.0248 g VFA-C g VSS−1 d−1). A hierarchy (acetate followed by butyrate followed by propionate) was evident when the kC rate was calculated on the basis of individual acids within the natural mixture. This hierarchy was also supported by the carbon consumption profiles.
    Enzyme and Microbial Technology 01/2007; 41:92-97. · 2.59 Impact Factor
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    ABSTRACT: This study explored the effectiveness of an electrochemical process to treat a sulfur dye wastewater from a textile industry. The treatment system included a 4.0 L reactor equipped with five steel electrode plates, and a separate sedimentation tank of equal liquid volume. The experimental part involved two distinct, sequential stages. In the first stage, the effect of initial pH and electrical charge (i.e., current times reaction time) on the treatment process was explored. Experiments were conducted in a factorial mode, involving three initial pH values (3, 4 and 5), and six electrical charges (ranging from 150 to 1,350 coulomb), respectively. Results indicated that chemical oxygen demand (COD), total suspended solids (TSS), and color removal efficiency improved with a decrease in initial pH and an increase in electrical charge. Overall, high percent removal values were observed ranging from 63% to 80% for COD, 81% to 96% for TSS, and 93% to 99% for color. During the second stage, the electrode corrosion pattern was investigated for a period of 45 days. Under stable operating conditions, electrode consumption was found to conform to Faraday's law. Moreover, process performance regarding COD, TSS, and color reduction was comparable to that obtained in the first stage of the study.
    Journal of Environmental Science and Health Part A 02/2006; 41(7):1183-95. · 1.25 Impact Factor
  • P. Elefsiniotis, D. Li
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    ABSTRACT: This study explored the effect of temperature and carbon source on the denitrification process. Batch experiments were conducted within the 10–30°C range, using either acetic acid, propionic acid or an 1:1 mixture (by weight) of the same acids as an external carbon source. A 5M NaNO3 solution was added to yield nitrate-nitrogen concentrations of 50, 100 and 200mg/L, and carbon to nitrogen (C:N) ratios of 2:1 and 4:1, respectively. It was observed that denitrification was feasible under all conditions investigated, provided that the initial reactor pH was adjusted to approximately 6.5. Overall, a temperature change from 10 to 20°C exerted a greater effect on both the specific denitrification and carbon consumption rates than a further temperature increase from 20 to 30°C, which was also evident in the corresponding temperature coefficient values. At a given temperature, the specific denitrification rate appeared to depend on the initial nitrogen concentration, while the specific carbon consumption rate was a function of the initial carbon content. Furthermore, a C:N ratio of 2:1 was sufficient for complete denitrification at all temperatures and types of carbon investigated. During the mixed VFA experiments, acetic acid was utilized faster than propionic acid, indicating a preferential utilization pattern. Finally, substantial alkalinity recovery was also observed in all runs, in accordance with the theoretically calculated values.
    Biochemical Engineering Journal - BIOCHEM ENG J. 01/2006; 28(2):148-155.
  • Source
    P Elefsiniotis, D G Wareham
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    ABSTRACT: The aim of this study was to explore the link between sustainable development and the ISO 14000 Environmental Manage-ment Series of Standards, with particular reference to the ISO 14001 standard. In order to do this, it was decided to evaluate the ISO 14000 series in the context of a large engineering facility; namely, the Canadian provincial Crown Corporation of Manitoba Hydro. The ISO 14000 series is in principle an effective system to manage an organization's self-prescribed environmental goals; however, its main limitations are that it does not require the demonstration of environmental performance and it is sometimes difficult to interpret and apply due to ambiguous language. The paper closes with speculations that despite these shortcomings, the essence of the ISO 14000 series of standards is in sympathy with the notion of sustainability.
    Journal of Professional Issues in Engineering Education and Practice - J PROF ISSUE ENG EDUC PRACT. 01/2005; 131(3).
  • H. Chin, P. Elefsiniotis, N. Singhal
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    ABSTRACT: A bench-scale study was carried out to investigate the potential to biologically treat 2,4-dicholophenoxyacetic acid (2,4-D) contaminated wastewater in an anaerobic sequencing batch reactor (ASBR), operated in the acid-phase digestion mode. The effects of 2,4-D feed concentration (20 to 200 mg L-1) and temperature (ambient and 33 degrees C) on biodegradation were investigated at a hydraulic retention time of 48 h and a solids retention time of 10 d, using glucose as a supplemental substrate. Following a long acclimation period of about 100 d, complete 2,4-D degradation was observed at feed concentrations of 20 and 100 mg L-1. However, at a 2,4-D concentration of 200 mg L-1, only 65% removal was achieved. Overall, operation at an ambient temperature resulted in a slightly better performance than that at 33 degrees C. An adaptation period of approximately a week was required any time the 2,4-D concentration was increased, indicating a sensitive behavior towards shock loadings. On the other hand, glucose
    01/2005; 4:57-63.
  • P Elefsiniotis, D G Wareham, M O Smith
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    ABSTRACT: This study investigates the ability of naturally-produced volatile fatty acids (VFAs) to act as a carbon source for the removal of nitrate-Nitrogen concentrations in the range of 20 to 200 mg/L. The VFAs were generated from an anaerobic digester treating a 1:1 mixture of starch-rich industrial and municipal wastewater. The experiments were carried out at an ambient temperature of 22+/-2 degrees C using 600 mL batch reactors containing VFA-rich effluent from the digester and prepared primary sludge. Nitrates added in the form of a 1 M potassium nitrate solution were observed to completely disappear in conjunction with significant recovery of pH and alkalinity (i.e. biological denitrification). In all cases, denitrification followed zero-order kinetics with an average rate constant of 2.67 mg/[Lh] and a mean specific denitrification rate of 0.0111 g NOx-N/g volatile suspended solids (VSS) per day. The denitrifier population had a preference for acetic acid which occurred in the largest quantity and was exhausted the most rapidly. The next two most abundant VFAs were butyric acid and propionic acid, which were consumed only after acetate concentrations began to decline. The third "choice" of the denitrifiers was valeric acid, thus it appears that denitrifying bacteria have a sequential preference for VFAs. In addition, they prefer VFAs over other more complex soluble organic carbon forms.
    Journal of Biotechnology 12/2004; 114(3):289-97. · 3.18 Impact Factor

Publication Stats

349 Citations
37.85 Total Impact Points

Institutions

  • 2001–2013
    • University of Auckland
      • Department of Civil and Environmental Engineering
      Auckland, Auckland, New Zealand
  • 2008–2012
    • Mahidol University
      • Department of Sanitary Engineering
      Bangkok, Bangkok, Thailand
  • 1998–2009
    • University of Manitoba
      Winnipeg, Manitoba, Canada
  • 1994–2004
    • University of British Columbia - Vancouver
      • Department of Civil Engineering
      Vancouver, British Columbia, Canada
  • 2003
    • University of Canterbury
      Christchurch, Canterbury Region, New Zealand