by Chung Ho Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 127-141). / Text in English; abstracts in English and Chinese. / by Chung Ho Yan. / Acknowledgments --- p.i / Abstract --- p.ii / Table of Contents --- p.v / List of Figures --- p.xi / List of Plates --- p.xiv / List of Tables --- p.xv / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Textile-Dyeing Industry in Hong Kong --- p.1 / Chapter 1.2 --- Processes Involved in Dyeing Industry --- p.3 / Chapter 1.2.1 --- Desizing --- p.3 / Chapter 1.2.2 --- Scouring --- p.3 / Chapter 1.2.3 --- Bleaching --- p.3 / Chapter 1.2.4 --- Mercerizing --- p.4 / Chapter 1.2.5 --- Dyeing and Printing --- p.4 / Chapter 1.2.6 --- Finishing --- p.4 / Chapter 1.3 --- Characterization of Wastewater of Dyeing Industry --- p.5 / Chapter 1.4 --- Toxicity of Effluent from Textile-Dyeing Industry --- p.9 / Chapter 1.5 --- Related Environmental Legislation --- p.9 / Chapter 1.6 --- Chemical Specific Approach and Toxicity Based Approach --- p.11 / Chapter 1.7 --- Whole-Effluent Toxicity (WET) Test --- p.13 / Chapter 1.8 --- Toxicity Identification Evaluation --- p.14 / Chapter 1.8.1 --- Phase I - Toxicity Characterization --- p.15 / Chapter 1.8.2 --- Phase II - Toxicity Identification --- p.15 / Chapter 1.8.3 --- Phase III - Toxicity Confirmation --- p.18 / Chapter 1.9 --- Toxicity Identification Evaluation on Effluent from Textile-Dyeing Industry --- p.19 / Chapter 1.10 --- Organisms Used for Toxicity Identification Evaluation --- p.20 / Chapter 1.11 --- Selection of Organisms for Bioassays --- p.20 / Chapter 2. --- OBJECTIVES --- p.24 / Chapter 3. --- MATERIALS AND METHODS --- p.25 / Chapter 3.1 --- Sources of Samples --- p.25 / Chapter 3.2 --- Whole Effluent Toxicity Test - Baseline Toxicity Test --- p.28 / Chapter 3.2.1 --- Microtox® test --- p.28 / Chapter 3.2.2 --- "Survival test of the marine amphipod, Hyale crassicornis" --- p.29 / Chapter 3.2.3 --- "Survival test of the brine shrimp, Artemia franciscana" --- p.33 / Chapter 3.2.4 --- "Survival test of the freshwater water flea, Daphnia magna" --- p.36 / Chapter 3.3 --- Toxicity Identification Evaluation ´ؤ Phase I Toxicity Characterization --- p.40 / Chapter 3.3.1 --- pH adjustment filtration test --- p.41 / Chapter 3.3.2 --- pH adjustment aeration test --- p.42 / Chapter 3.3.3 --- pH adjustment cation exchange test --- p.43 / Chapter 3.3.4 --- pH adjustment anion exchange test --- p.44 / Chapter 3.3.5 --- pH adjustment C18 solid phase extraction (C18 SPE) test --- p.45 / Chapter 3.3.6 --- pH adjustment XAD-2 solid phase extraction (XAD-2 SPE) test --- p.46 / Chapter 3.4 --- Toxicity Identification Evaluation - Phase II Toxicity Identification --- p.47 / Chapter 3.4.1 --- Determination of anions --- p.48 / Chapter 3.5 --- Toxicity Identification Evaluation ´ؤ Phase III Toxicity Confirmation --- p.50 / Chapter 3.5.1 --- Mase balance test --- p.50 / Chapter 3.5.2 --- Spiking test --- p.51 / Chapter 4. --- RESULTS --- p.52 / Chapter 4.1 --- Characteristics of Samples --- p.52 / Chapter 4.2 --- Whole Effluent Toxicity Test - Baseline Toxicity Test --- p.52 / Chapter 4.2.1 --- Toxicity of effluent sample determined by the Microtox® test --- p.52 / Chapter 4.2.2 --- Toxicity of effluent samples determined by Hyale crassicornis survival test --- p.52 / Chapter 4.2.3 --- Toxicity of effluent samples determined by Artemia franciscana survival test --- p.57 / Chapter 4.2.4 --- Toxicity of effluent samples determined by Daphnia magna survival test --- p.51 / Chapter 4.3 --- Toxicity Identification Evaluation - Phase I Toxicity Characterization --- p.57 / Chapter 4.3.1 --- Toxicity characterization of effluent samples determined by Hyale crassicornis survival test --- p.60 / Chapter 4.3.2 --- Toxicity characterization of effluent samples determined by Artemia franciscana survival test --- p.68 / Chapter 4.3.3 --- Toxicity characterization of effluent samples determined by Daphnia magna survival test --- p.68 / Chapter 4.4 --- Toxicity Identification Evaluation ´ؤ Phase II Toxicity Identification --- p.72 / Chapter 4.4.1 --- Baseline anion concentrations in effluent samples --- p.75 / Chapter 4.4.2 --- Sample1 --- p.75 / Chapter 4.4.3 --- Sample2 --- p.75 / Chapter 4.4.4 --- Sample3 --- p.75 / Chapter 4.4.5 --- Sample4 --- p.81 / Chapter 4.4.6 --- Sample5 --- p.81 / Chapter 4.4.7 --- Sample6 --- p.81 / Chapter 4.5 --- Toxicity Identification Evaluation 一 Phase III Toxicity Confirmation --- p.85 / Chapter 4.5.1 --- Mass balance test results --- p.85 / Chapter 4.5.2 --- Spiking test results --- p.96 / Chapter 5. --- DISCUSSION --- p.102 / Chapter 5.1 --- Whole Effluent Toxicity Test ´ؤ Baseline Toxicity Test --- p.102 / Chapter 5.1.1 --- Toxicity of effluent sample determined by the Microtox® test --- p.102 / Chapter 5.1.2 --- Toxicity of effluent samples determined by Hyale crassicornis survival test --- p.103 / Chapter 5.1.3 --- Toxicity of effluent samples determined by Artemia franciscana survival test --- p.104 / Chapter 5.1.4 --- Toxicity of effluent samples determined by Daphnia magna survival test --- p.104 / Chapter 5.2 --- Toxicity Identification Evaluation ´ؤ Phase I Toxicity Characterization --- p.105 / Chapter 5.2.1 --- pH adjustment filtration test --- p.105 / Chapter 5.2.2 --- pH adjustment aeration test --- p.106 / Chapter 5.2.3 --- pH adjustment cation exchange test --- p.106 / Chapter 5.2.4 --- pH adjustment anion exchange test --- p.106 / Chapter 5.2.5 --- pH adjustment C18 solid phase extraction (C18 SPE) test --- p.107 / Chapter 5.2.6 --- pH adjustment XAD-2 solid phase extraction (XAD-2 SPE) test --- p.107 / Chapter 5.3 --- Toxicity Identification Evaluation - Phase II Toxicity Identification --- p.107 / Chapter 5.3.1 --- Efficiency on chemical reduction of pH adjustment filtration test --- p.109 / Chapter 5.3.2 --- Efficiency on chemical reduction of pH adjustment aeration test --- p.109 / Chapter 5.3.3 --- Efficiency on chemical reduction of pH adjustment cation exchange test --- p.109 / Chapter 5.3.4 --- Efficiency on chemical reduction of pH adjustment anion exchange test --- p.109 / Chapter 5.3.5 --- Efficiency on chemical reduction of pH adjustment CI8 SPE test --- p.109 / Chapter 5.3.6 --- Efficiency on chemical reduction of pH adjustment XAD-2 SPE test --- p.110 / Chapter 5.4 --- Toxicity Identification Evaluation - Phase III Toxicity Confirmation --- p.110 / Chapter 5.4.1 --- Mass balance test results --- p.110 / Chapter 5.4.2 --- Spiking test results --- p.114 / Chapter 5.5 --- Comparison of Toxicant(s) Identified in the Six Dyeing Industrial Effluents --- p.117 / Chapter 5.6 --- Toxicant(s) Identified in Textile-Dyeing Industrial Effluent --- p.119 / Chapter 5.7 --- "Sources, Fate and Treatment of Sulfite Ion" --- p.120 / Chapter 5.8 --- Toxicity of Sulfite Ion --- p.121 / Chapter 5.9 --- Effect of Salinity on the Toxicity of Sulfite Ion --- p.122 / Chapter 5.10 --- Recommendation --- p.123 / Chapter 6. --- CONCLUSIONS / Chapter 7. --- REFERENCES / Chapter 8. --- APPENDICES

Thesis (LL. M.)--George Washington University, 1992. / Typescript. Includes bibliographical references.

Thesis (MSc Food Sc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The distillery industry produces large volumes of waste water with a high organic content throughout the year. These effluents must be treated in some manner before being discharged or recycled in the factory. Several treatment options are in use presently, but they all have disadvantages of some nature, such as long retention times, bad odours or the need for large areas of land. Considerable interest has been shown in the application of anaerobic digestion, especially the UASB design (upflow anaerobic sludge blanket), to treat this high strength waste water. Thus, the aim of this study was to investigate the efficiency of an upflow anaerobic sludge blanket (UASB) bioreactor using full-strength distillery effluent. The activity of the bacteria in the biogranules was also evaluated by developing an easy and reliable activity method to estimate the general biogas and methanogenic activity and to calibrate this method using different anaerobic granules from different sources. The influence of high strength distillery effluent on the anaerobic digestion process was investigated using a mesophilic lab-scale UASB bioreactor. During the experimental study, the organic loading rate (OLR) was gradually increased from 2.01 to 30.00 kgCOD.m-3.d-1, and simultaneously, the substrate pH was gradually lowered from 7.0 to 4.7. It was found that at an OLR of 30.00 kgCOD. m-3.d-1,the pH, alkalinity and biogas production stabilised to average values of 7.8, 6 000 mg.l-1 and 18.5 I.d-1 respectively. An average COD removal> 90% was found indicating excellent bioreactor stability. The low substrate pH holds considerable implications in terms of operational costs, as neutralisation of the biorector substrate is no longer necessary. The accumulation of fine solids present in the distillery substrate was found at the higher OLR's and resulted in the granular bed increasing with subsequent biomass washout and a lowering in efficiency parameters. However, a possible pre-treatment filtration of these fine solids would eliminate this problem. The success of the upflow anaerobic sludge bed (UASB) process is mainly due to the capability of retaining the active biomass in the reactor. Over the years, several methods have been developed to characterise and quantify sludge activity but each has advantages and disadvantages. There is thus an increasing need for a rapid method to evaluate the activity of the granular biomass. The activity method of Owen et al. (1979) as adapted by Lamb (1995), was thus evaluated in terms of efficiency and applicability in determining the activity of granular samples. The method was found to be inaccurate as well as time consuming and it was thus modified. Results obtained with the modified assay method were found to be more accurate and the impact of the different test substrates (glucose, lactate, acetate and formate) on activity, was more evident. The activity of seven different anaerobic granules, was subsequently evaluated. Biogas (Ss) and methanogenic (SM) activity was not measured in volume of gas produced per unit COD converted or volatile suspended solids (VSS), but as tempo of gas production (ml.h-1) in a standardised basic growth medium. The activity data obtained were also displayed as bar charts and "calibration scales". This illustrative depiction of activity data gave valuable information about population dynamics as well as possible substrate inhibition. The "calibration scales" can also be used to group the general biogas (Ss) and methanogenic activities (SM) of any new biogranule relative to active (O-type) and inactive (W-type) anaerobic granules, providing that the same method of activity testing is used. The "calibration scales" can thus be used to give a fast indication of how the activity value of one sample relates to the activity values of other granules, even when using different test substrates. / AFRIKAANSE OPSOMMING: Die stokery industrie produseer groot hoeveelhede afvalwater, wat hoë ladings van organiese materiaal gedurede die hele jaar bevat. Hierdie afvalwater moet op een of ander manier behandel word voordat dit gestort of vir hergebruik aangewend kan word. Daar is tans verskeie behandelingsmetodes wat gebruik kan word, maar elk het sy eie tekortkominge soos bv. lang retensie tye, onaangename reuke of die behoefte aan groot stukke oop grond. Groot belangstelling is getoon vir die gebruik van anaerobiese vertering, en meer spesifiek die "uflow anaerobic sludge blanket" UASB bioreaktor vir die behandeling van stokery uitvloeisels. Die doel van die studie was dus om die algehele effektiwiteit van 'n UASB bioreaktor, wat onverdunde stokery uitvloeisel behandel, te evalueer. Die methanogene- en algehele aktiwiteit van die bakterië in die biogranules was ook ge-evalueer deurdat 'n maklike en betroubare aktiwiteitsmetode omtwikkel is, waarna hierdie metode ook toegepas was op 'n reeks van verskillende tipe biogranules. Die invloed van volsterkte stokery uitvloeisel op die anaerobiese verteringsprosesse was ondersoek met die gebruik van 'n mesofiele laboratoriumskaal UASB bioreaktor. Gedurende die eksperimentele studie, was die organiese ladingstempo (OLT) verhoog van 2.01 na 30.00 kgCSB.m-3.d-1 (CSB = chemiese suurstof behoefte) met die gelyktydige verlaging in die pH van die bioreaktorsubstraat van 7.0 na 4.7. Dit was vasgestel dat met 'n OLT van 30.00 kgCSB.m-3.d-1, die pH, alkaliniteit en biogas geproduseer, gestabiliseer het na gemiddelde waardes van 7.8, 6000 mg.-1 en 18.5l.d-1 , respektiewelik, sowel as 'n gemiddelde CSB verwydering van> 90%. Al hierdie waardes dui uitstekende bioreaktor stabiliteit aan. Die lae bioreaktorsubstraat pH kan van groot waarde wees vir die industrie, aangesien neutralisering van die uitvloeisel nie meer nodig is nie en kan sodoende die operasionele koste van die proses verlaag. Die konsentrering van fyn opgeloste soliedes in die bioreaktor by hoë OLT's, kan egter problematies raak, aangesien dit die granule-bed kan vergroot en veroorsaak dat van die biomassa uitspoel en kan verlore gaan. Die verlies van aktiewe biomassa kan die effektiwiteitsparameters negatief beinvloed, maar die plasing van 'n filterings stap voor die verterings stap, behoort hierdie probleem op te los. The sukses van die UASB-stelsel rus op die versekering dat die aktiewe biomassa in die reaktor behoue bly. Oor die jare was daar 'n verskeidenheid van aktiwiteitstoetsings-metodes ontwikkel, elk met sy eie nadele. Daar bestaan dus nog steeds 'n groot behoefte vir die daarstelling van 'n aktiwiteitstoetsings-metode wat vinnig en maklik is om uittevoer. Die aktiwiteitstoetsings-metode van Owen et al. (1979) wat deur Lamb (1995) aangepas is, was in terme van sy effektiwiteit en toepaslikheid ten opsigte van die gebruik daarvan vir aktiwiteitstoetsing vir biogranules, ge-evalueer. Dit is bevind dat die metode onakkuraat sowel as tydsrowend was en gevolglik dus aangepas. Die aangepaste metode het meer akkurate resultate gelewer en die impak van die verskillende toetssubstrate (glukose, laktaat, asetaat en formaat) op die granules het ook meer duidelik na vore gekom. Gevolglik was die aktiwiteit van sewe verskillende anaerobiese biogranules ondersoek. Die eenheid waarin atiwiteitsresultate aangegee is, was nie in volume gas geproduseer per eenheid CSB verwyder of per hoeveelheid gesuspendeerde vlugtige vetsure in die biomassa nie, maar as tempo van biogas (S8)- of metaan (SM)produksie (ml.h-1). Die data wat op hierdie wyse bekom was, is gebruik om staafdiagramme sowel as "kalibrasie skale" daar te stel. Hierdie illustrerende wyse om aktiwiteitsdata uit te beeld verskaf waardevolle informasie ten opsigte van die interaksies tussen die verskillende populasies in die granule en kan ook die aanwesigheid van moontlike substraat inhibisie aandui. Die "Kalibrasie skale" kan ook gebruik word om die algehele (SB) en methanogene (SM)aktiwiteite van einge nuwe biogranule vinnig te klassifiseer ten op sigte van 'n aktiewe (O-tipe) en 'n minder aktiewe (W-tipe) anaerobiese granules, mits dieselfde metode gebruik word om die aktiwiteits data te bekom.

CAPES / As indústrias de celulose são caracterizadas pelo alto consumo de água em seus processos produtivos, gerando consequentemente grandes volumes de efluentes líquidos que apresentam na maior parte de sua composição compostos lignínicos, matéria orgânica, cor e toxicidade. O efluente de celulose, quando não tratado ou tratado de forma indevida, pode comprometer a qualidade da água dos corpos receptores, por conter substâncias tóxicas à comunidade aquática. O objetivo do trabalho foi avaliar a eficiência de tratamento de efluente de celulose e papel por reator MBBR, através da remoção de matéria orgânica (DQO e DBO5), compostos fenólicos, cor, compostos lignínicos e aromáticos. Para isso um reator MBBR em escala de bancada foi operado por 180 dias com diferentes velocidades de carga orgânica 0,2; 0,4; 1,2; 4,0; 9,0 kgDQO/L.d. Neste foi quantificada também a biomassa aderida e em suspensão na massa liquida. O efluente analisado apresentou 48 e 94% de remoção de DQO e DBO5 respectivamente, também houve remoção de compostos fenólicos e cor de 24 e 12% para VCO de 0,4 kgDQO/L.d, para mesma VCO a remoção de compostos lignínicos e aromáticos foi de 16 e 8,5 % respectivamente. / The pulp mills are characterized by high water consumption their production processes, thereby generating large volumes of effluents that present in most of composition lignínicos compounds, organic matter, color and toxicity. The wastewater from pulp, if left untreated or treated improperly, can compromise the water quality of receiving waters, which contain substances toxic to the aquatic community. The objective of this study was to evaluate the efficiency of wastewater treatment of pulp and paper by MBBR reactor, through the removal of organic matter (COD and BOD5), phenolic compounds, color, and aromatic compounds lignínicos. To this reactor MBBR bench scale was operated for 180 days with different speeds organic load 0.2, 0.4, 1.2, 4.0, 9.0 kgCOD / Ld This was also quantified and attached biomass in suspension in the liquid mass. The wastewater analysis showed 48 and 94% removal of COD and BOD5 respectively, were also removing phenolic compounds and color of 24 and 12% for 0.4 kgDQO VCO / Ld VCO same for removal of aromatic compounds and was lignínicos 16 and 8.5% respectively.

Submitted in partial fulfillment of academic requirements for the degree of Masters of Technology: Department of Chemical Engineering, Durban University of Technology, 2009. / The primary objective of this project was to establish a screening protocol which could be used to access high strength/toxic effluent for toxicity and degradability prior to being disposed in wastewater treatment works. The serum bottle method (materials and method section) is simple, makes use of small glass vials (125 mℓ-volume were used in this research) which do not require any stirring nor feeding device or other engineered tool: a serum bottle is sealed immediately after all components are poured inside and thereafter conducted in a batch mode and occasionally shaken to ensure adequate homogenisation of the components. The only variables which are regularly measured are the volume of biogas produced and gas composition. The two assays, originally developed by Owen et al. (1979) to address the toxicity and the biodegradability have been combined in a single test called AAT, Anaerobic Activity Test, which enables one to assess simultaneously the inhibitory effect on the methanogenic biomass and the biodegradability of the test material as well as the ability of the biomass to adapt to the test material and therefore to overcome the initial inhibition. The screening protocol is illustrated in Annexure A. The protocol consists of a sequence of assays which employ the serum bottle methodology. A first step of the procedure is aimed at rapidly estimating whether the effluent is potentially toxic to the methanogenic biomass and in what concentration. The second step is a more extensive screening, aimed at precisely characterising the toxicity of the effluent, the extent of biodegradation that can be achieved, as well as at establishing whether a potential for adaptation of the biomass exists upon exposure. If the sample passes the screening stage, the same serum bottle method will be used to conduct a series of batch co-digestion experiments aimed at evaluating a convenient volumetric ratio between the test material and the readily biodegradable substrate. Finally, a laboratory-scale codigestion trial could simulate the full-scale process, thus enabling the selection of appropriate operating conditions for the start-up of the full-scale implementation. This the protocol has been used to assess the amenability to be anaerobically (co)digested of four industrial effluents, i.e. size and distillery effluents which are classified as high strength and scour and synthetic dye effluents classified as toxic. From the biodegradability and toxicity assays the following conclusions were drawn. The size and distillery effluent were found to be ii degradable at 32 g COD/ℓ and 16 g COD /ℓ concentrations respectively. Concentrations higher than these stipulated above were found inhibitory. Scour effluent was found to be recalcitrant at all concentration tested and synthetic dye was 100 % degradable at 0.12 g COD/ℓ and lower and highly inhibitory at concentration higher than 1.1 g COD/ℓ. Co-digestion experiment using serum bottle AAT method were undertaken between effluents i.e. size + distillery, size + scour, distillery + synthetic dye in an attempt to verify whether the digestion performance benefits from simultaneous presence of the two substrates. The volumetric ratios between the effluents were 1:1, 1:2, 2:1. The presence of two mixtures in the case of size and distillery had better methane production compared to individual substrate i.e. size or distillery separate. The mixture with volumetric flow rate ratio of 2:1 (size: distillery) was preferable in terms of process performance as it had highest COD removal compared to the other mixtures /ratios and individual substrates. The mixture of size and scour (2:1) had highest degradation percentage compared to other ratios but not high enough to qualify as degradable (less than 50 %). The mixture of distillery and synthetic dye had the same pattern with ratio of 2:1 giving the best COD conversion. The pattern than can be drawn from the degradability of mixtures is: the degradability of mixtures increase with the increasing amount of the most biodegradable compound/effluent in the mixture. Serum bottle results provided the detailed information regarding the safe operating parameters which should be used during the starting point for the larger scale investigation i.e. lab-scale investigations. The lab scale investigations were conducted primarily to validate screening and monitor how the digestion progresses and also to provide data for future project i.e. pilot plant investigation. Other effluents i.e. scour and synthetic dye and their co-digestion mixture were excluded from the lab-scale investigations since they were found to be non- biodegradable i.e. their COD conversion was less the 50 % in the screening protocol. Due to time constrains and other technical difficulties in the laboratory, the co-digestion of size and distillery mixture trials we not conducted on the laboratory scale. Laboratory-scale digestion trials showed that the best organic loading rate for distillery effluent in terms of reactor performance and stability was 1.0g COD/ℓ with efficiency of about 45 %, and for size was 2.0g COD/ℓ with an efficiency of 40 %. The efficiencies obtained in both effluents trials could be greatly improved by acclimation; however these results showed that the digestion of these effluents on the bigger scale is possible. / Water Research Commission

Thesis (MScEng)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Can salts present in an aqueous industrial effluent be retained by the [me ash that is produced as a by-product of gasification or by power stations utilising coal as the raw material? In order to answer this question, the actual chemistry that occurs during the mixing and settling process, needs to be understood. At the Sasol Secunda petrochemical plants in South Africa, ash is produced as a byproduct from the gasification of coal, and by the coal-fired power stations (steam plants). The [me portion of the ash (± 50J.lm in diameter) is disposed of through the use of a closed loop wet ash disposal system. The ash is transported as a slurry to the disposal sites (ash darns). The industrial effluent used to transport the ash consists mainly of the recycled ash effluent, known as clear ash effluent (CAE), as well as a variety of process waste streams containing high concentrations of salts. This mixture of ash and water is pumped to ash dams, where the ash is allowed to settle and is therefore separated from the effluent. From the ash darns the effluent flows into evaporation dams, and finally into CAE dams before being returned to the ash plant in Sasol 2 and 3 to be mixed once again with the ash. During this contact time of the ash with the water certain chemical reactions may occur. If one understands what chemical reactions occur during this process, and under what conditions they occur, then it will be possible to utilise the ash disposal system to its full potential, possibly enhancing the salt retention ability. An investigation was thus conducted into what processes actually occurs during the entire ash water contact period. The overall aim of the project was to obtain an understanding of the functioning of the [me ash disposal system so that its efficiency can be improved upon, and furthermore, so that the ash darns can be utilised more effectively in retaining salts. This investigation focussed on the chemical reactions that occur when an industrial effluent is mixed with fine ash, and consisted of four main aspects: • A literature survey on related issues. • An analysis and evaluation of the changes that occur in the actual disposal system. • Laboratory column experiments to investigate, in more detail, the different chemical reactions, which occur during the different stages of the disposal process. • The drilling of boreholes into the ash dams to obtain core material at a variety of depths and locations for analysis purposes. From this investigation it was concluded that salts are retained in the ash dams; based on the results obtained from the laboratory column experiments and the production rate of the fine ash from Sasol 2 and Sasol 3, the potential amount of salts that can be removed from the system (either due to precipitation or water retention in the ash dams) is approximately 95 tons/day. The salts that were found to be most pertinent to the wet ash disposal system utilised at Sasol, Secunda, are Ca, S04, Na, and Cl. Of these, Ca, S04 and Na were identified in literature to be the components most commonly associated with fly ash leachate. The Ca chemistry, which occurs in the ash disposal system, was explored extensively. Is was found that Ca, which is initially present in the fresh fine ash as lime, is leached from the ash into the effluent, where it reacts with carbon dioxide in the atmosphere, and is therefore removed from the system due to the precipitation of calcite. Sodium, S04, and Cl were all found to be retained in the ash; the S04 appears to be retained in a stable form within the ash, not merely due to hydraulic retention, which suggests that the ash system has the potential to act as a salt sink for S04 ions. The mechanism of salt retention in the ash darns was found to be predominantly by means of hydraulic retention, and therefore the salts have the potential to be flushed out of the ash dams into the underlying soil material. However, results from the core drilling exercise revealed that there doesn't appear to be a significant seepage of elements from the ash fill material into the underlying vertisol material. Some components (AI, Fe, Na, K, Mg, Cr, P, Ti and V) from the older, and inactive ash dam, do appear to have percolated into the underlying material. However, a significant amount of water, and therefore salts, are still retained in the ash dam. In terms of the mineralogical composition of the ash dams, a significant difference was observed between the mineral phases present in the ash fill material of an active and an inactive ash dam. Ettringite was detected throughout the borehole drilled into the inactive ash darn, and was not evident at all in the core material from the two boreholes drilled into the active dam, which suggests that this mineral is formed in the ash darns over a long time period. The minerals quartz and mullite were found in the fresh [me ash as well as in most of the core material obtained from the drilling exercise. The mineralogical composition of the ash fill samples, from the boreholes drilled into the centre of the active and inactive ash darns, was found to be very consistent with depth. This finding, combined with the fact that the chemical composition of the core samples varied more significantly in the borehole located near the edge of the active fine ash darn, indicated that the lateral position of the ash in the ash dam influences the chemical reactions that occur. Overall, from this investigation it was concluded that although the chemistry, involved in the mixing of an industrial effluent with fine ash, is extremely complex and site-specific, it is possible to determine the most significant changes which occur within a wet ash disposal system. Besides providing one with a better understanding of the working of the Secunda ash disposal system, the results of this investigation have also provided the framework for future research on this topic and related issues, i.e. the construction of a pilot scale ash darn set-up; further column experiments to investigate the extent to which S04 ions can be removed from the system; the influence of the addition of CO2 to the system; and more extensive core drilling in the vicinity of the ash darns. / AFRIKAANSE OPSOMMING: Kan soute teenwoordig in 'n industriële uitvloeisel teruggehou word in fynas geproduseer as neweproduk van steenkoolkragsentrales? Om 'n antwoord op hierdie vraag te kry, moet die chemiese reaksies wat gebeur tydens die meng en wegdoening van die as en aswater verstaan word. By die Sasol petrochemiese aanlegte in Secunda, Suid Afrika, word fynas geproduseer as 'n neweproduk in die vergassing en die stoomopwekkingprosesse. Die fynas (50)lm diameter) word weggedoen deur 'n geslote nat asstelsel. Die industriële uitvloeisel wat gebruik word vir die vervoer van die as bestaan hoofsaaklik uit hergebruikte aswater (genoem CAE - clear ash effluent), asook 'n verskeidenheid ander prosesafvalstrome wat hoë konsentrasies soute bevat. Die mengsel van as en aswater word in 'n asflodder gepomp na die asdamme, waar die as besink en sodoende geskei word van die waterfase (aswater). Vanaf die asdamme vloei die aswater na verdampingsdamme, en daarna na die CAE damme, vanwaar die CAE weer na die Sasol aanleg teruggepomp word om weer met as gemeng te word. Gedurende die kontak tussen die CAE en as gebeur sekere chemiese reaksies. Indien hierdie reaksies verstaan word, en onder watter toestande dit plaasvind, kan die asdamstelsel tot volle kapasiteit benut word deur moontlik die soutretensie binne die asdam te verhoog. 'n Ondersoek is gedoen om te bepaal watter prosesse plaasvind gedurende kontak tussen die as en water. Die doel van die ondersoek was om 'n beter begrip te kry oor die funksionering van die fynas-wegdoeningstelsel en om te bepaal of die asdamme meer effektiefbedryfkan word om moontlik meer soute te akkommodeer. Die ondersoek het uit vier hoofaspekte bestaan: • Literatuuroorsig, • 'n Analise en evaluering van die veranderinge wat plaasvind oor die asdamstelsel, • Laboratoriumskaal kolomeksperimente om in meer besonderhede die chemiese reaksies wat 'n rol in die aswaterstelsel speel, te bepaal, en • Die boor van toetsgate op die bestaande asdamme om boorkerne te ontleed by bepaalde dieptes en liggings. Uit die ondersoek is bevind dat soute wel in die asdamme behou word. As die kolomtoetse as basis gebruik word, en die produksietempo van fynas vanaf Sasol 2 en 3, dan kan daar 'n potensiële 95 ton soute per dag deur die asstelsel verwyder word (deur hoofsaaklik waterretensie en presipitasie van soute). Die mees prominente soute wat in die Sasol asstelsel voorkom is Ca, S04, Na, en Cl. Vanhierdie soute, is Ca, S04, en Na deur die literatuur geïdentifiseer as komponente wat met vliegas loog geassosieer word. Die Ca chemie, wat in die asstelsel plaasvind, is in besonderhede ontleed. Dit is bevind dat Ca, teenwoordig in die vars fynas as kalk, vanuit die as in die aswater geloog word, waar dit dan met atmosferiese CO2 reageer en dan vanuit die stelselverwyder word deur die presipitasie van kalsiet. Natrium, S04 en Cl word in die as teruggehou. Dit wil voorkom asof die S04 in 'n stabiele vorm in die as teruugehou word, nie net deur die hidrouliese retensie nie en dat die asstelsel dalk as 'n potensiële sink vir S04 kan optree. Die meganisme van soutretensie in die asdamme is hoofsaaklik deur hidrouliese retensie, met die gevolg dat die soute potensieel in die onderliggende grond uitgewas kan word. Die resultate van die boorkernondersoek wys egter dat daar nie beduidende uitwassing van hierdie soute in die grond is nie. Dit wil voorkom of sekere komponente (Al, Fe, Na, K, Mg, Cr, P, Ti en V) van die ou en onaktiewe asdam in die grond geloog is. 'n Beduidende verskil was gevind tussen die minerale fases in die asmateriaal van die aktiewe en onaktiewe asdamme. Ettringiet was teenwoordig deur die hele diepte van die boorkern van die onaktiewe dam, maar was nie teenwoordig in beide boorkerns van die gate op die aktiewe asdam nie. Dit impliseer dat hierdie mineraaloor 'n langer tyd gevorm word. Kwarts en mulliet was deurentyd in al die boorkerne teenwoordig. Die mineralogie van die boorkern van die middel van die aktiewe asdam was baie konstant met diepte (in teenstelling met dié van die boorkern op die kant van die asdam) wat daarop dui dat die laterale posisie van die as in die asdam die chemiese reaksies wat mag plaasvind kan beïnvloed. Die ondersoek bevestig dat alhoewel die chemiese reaksies betrokke in die aswaterstelsel baie kompleks en liggingspesifiek is, die mees beduidende veranderinge wat in die asstelsel plaasvind, wel bepaal kan word. Die ondersoek het benewens 'n beter begrip van hoe die asdamme reageer, ook 'n raamwerk gegee vir verdere navorsing in hierdie veld, bv. die bou van 'n loodsskaal-asdam, verdere kolomtoetse om die vermoë van die asstelsel om S04 ione te verwyder te bepaal en die invloed van gemanipuleerde kalsiet presipitasie deur die byvoeging van CO2.

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Biological removal of sulphate from wastewater can be achieved by using a gas mixture consisting of 80% hydrogen and 20% carbon dioxide as energy and carbon sources. A novel reactor, including a venturi device for optimal hydrogen gas-liquid contact, and geotextile for immobilisation of the sulphate reducing bacterial community, was introduced. Efficient, relatively stable sulphate removal was obtained when the reactor was operated in continuous mode. The maximum sulphate removal rate obtained when the reactor was 8% packed with geotextile, was 1 g S04/(L.d) and 4 g S04/(L.d) when the reactor was 80% packed with geotextile. Kinetic batch studies showed that the highest sulphate removal rates were obtained at 29.5 °C; a pH of 7.5; initial sulphate concentration of 4000 mg/L; initial alkalinity of 1600 mg/L; cobalt concentration of 3 mg/L and when excess hydrogen gas was fed compared to what is stoichiometrically required (900 ml/min). Nickel addition showed inhibition at increased concentrations (>3 mg/L). The biofilm structure was observed on the geotextile with electron microscopy, while the viability of the biofilm was indicated with fluorescence microscopy. These observations indicated the suitability of the geotextile as a support material for biofilm formation in the sulphate reducing system. The stability of the sulphate reducing community was analysed, using the T-RFLP protocol. It was shown that the composition of the community changed after a period of 3 months, when the reactor was subjected to environmental changes. The reactor was also observed to be more efficient in terms of sulphate removal after the environmental changes, of which the temperature change from an average of 39 to 29.5 °C was the most prominent. Subsequently, it was speculated that the population shift was in favour of a more efficient system for sulphate removal. A dynamic, viable, mesophilic sulphate reducing community was therefore observed on the geotextile support, responsible for successful sulphate removal in a novel venturi-reactor. Defining optimal operating conditions, and a knowledge of biofilm structure and composition may contribute to the successful implementation of the biological sulphate removal component of the integrated chemical-biological process for the treatment of industrial wastewater, when hydrogen and carbon dioxide are supplied as the energy and carbon sources, respectively. / AFRIKAANSE OPSOMMING: Ongewenste industriële afval-water kan biologies behandel word deur 'n gasmengsel van 80% waterstof en 20% koolstofdioksied te gebruik vir sulfaat verwydering. 'n Reaktor wat 'n venturi apparaat bevat vir optimale waterstofgas-vloeistof kontak, asook geotekstiel vir die immobilisasie van die bakteriële sulfaatverwyderende gemeenskap, is bekend gestel. Effektiewe, relatief stabiele sulfaatverwydering is waargeneem sodra die reaktor op 'n kontinue basis gevoer is. Die optimale sulfaat verwyderingstempo wat bereik is as die reaktor 8% met geotekstiel gevul was, was 1 g S04/(L.d) en 4 g S04/(L.d) wanneer die reaktor 80% met geotekstiel gevul was. Kinetiese groepstudies het getoon dat die beste sulfaatverwydering bereik is by 'n gemiddelde temperatuur van 29.5 °C; pH van 7.5; aanvanklike sulfaatkonsentrasie van 4000 mg/L; aanvanklike sulfied konsentrasie van 268 mg/L; aanvanklike alkaliniteit van 1600 mg/L; kobalt konsentrasie van 3 mg/L, asook wanneer 'n oormaat waterstofgas gevoer is (900 ml/min), in vergelyking met wat stoichiometries benodig word. 'n Verhoogde byvoeging van nikkel by die voerwater (3 mg/L), het tekens van inhibisie getoon. Die biofilm struktuur is waargeneem op die geotekstiel met behulp van 'n elektronrnikroskoop, terwyl die lewensvatbaarheid van die biofilm aangedui is met behulp van fluoressensie mikroskopie. Hiermee is die bruikbaarheid van geotekstiel as 'n ondersteunings-matriks bevestig. Die stabiliteit van die sulfaatverwyderende gemeenskap is ondersoek deur die T-RFLP protokol te gebruik. Hiermee is aangedui dat die samestelling van die gemeenskap verander het na die 3 maande toets periode, toe die reaktor onderhewig was aan omgewings veranderinge. Die reaktor het ook 'n verbetering in sy sulfaatverwyderings vermoë getoon na hierdie tydperk van omgewingsveranderinge, waarvan 'n temperatuur verandering vanaf 'n gemiddeld van 39 na 29.5 °C die prominentste was. Dit is dus gespekuleer dat die populasie verskuiwing ten gunste was van 'n beter sisteem vir sulfaatverwydering. 'n Dinamiese, lewensvatbare, mesofiliese sulfaatreduserende gemeenskap, verantwoordelik vir die sulfaatverwydering in die venturi-reaktor, is dus waargeneem op die geotekstiel as 'n ondersteuningsmatriks. Met hierdie evaluasie kan die insig wat verkry is in die reaktor samestelling en die optimale kondisies vir die reaktor werking, bydra tot die suksesvolle implementasie van die biologiese komponent, in die geïntegreerde chemies-biologiese proses vir die behandeling van industriële afval water, wanneer 80% waterstof en 20% koolstofdioksied gas as energie en koolstofbron respektiewelik, gebruik word.

published_or_final_version / Urban Planning and Environmental Management / Doctoral / Doctor of Philosophy

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management