published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy

Water treatment residues (WTRs) are the by-product from the production of potable water. They consist mainly of the precipitated hydrous oxides of the treatment chemicals, and materials removed from the raw water. This study investigated the range of treatment processes and residues produced in South Africa, and two WTRs were selected for testing on selected soils and mine materials. A questionnaire was developed and sent to water treatment authorities across South Africa. Information on the treatment chemicals, dosages, volumes and current disposal practices, and a sample of WTR from each treatment plant were requested. Eleven, of 21 authorities, returned completed questionnaires, representing 37 water treatment facilities. Organic polymers were the most commonly used treatment chemical, with most plants also using lime. Other less frequently used chemicals and additives were Alz(S04)3.14I-hO, Fe2(S04)3, FeC!), sodium aluminate, activated silica, activated charcoal, CO2 and bentonite. Information given regarding residue thickening and disposal was poor. Samples from Rand Water, Umgeni Water (Midmar), Midvaal Water Company, Amatola Water and Cape Metropolitan Council (Faure) were received or collected. An additional sample from Faure was also received, representing a change in the treatment process. These samples were analysed for a range of chemical and physical characteristics. These analyses showed that the WTRs had the potential to supply some plant nutrients (Ca, Mg, Fe, S) but that metal toxicity may be a problem, in particular Mn in the Faure WTR, and that P adsorption may be severe. The samples selected to test the potential for land disposal were from Rand Water and Faure. A pot experiment tested the growth of Eragrostis tefJ, Cenchrus ciliaris and Digitaria eriantha in mixtures of Rand WTR and material from a coal mine i.e., a sandy soil material, spoil material and coal combustion ash, at rates of 0, 50, 100, 200 and 400 g kg" with a uniform fertiliser treatment applied to all mixtures. The grass was harvested on three occasions and the mean total yield (dry mass) determined, as well as nutrient uptake. The pots were leached after each harvest and the pH and electrical conductivity determined. The soil, spoil and ash were characterised and pH, EC and water retention characteristics of the mixtures determined. Growth of the grasses in the ash treatments was poor and these were terminated. Eragrostis tefJ grown in the soil showed a decrease in mean total yield with increasing WTR application rate, but yield was good up to the 200 g kg" treatment at the first harvest, declining substantially by the second harvest. In general C. ciliaris and D. eriantha grown in the soil showed a decrease in mean total yield for all harvests with increasing WTR application. The yield of E. /ejJ, grown in the spoil, increased up to 100 g kg,l WTR addition, but decreased thereafter. Digitaria eriantha showed a decrease in yield, and C. ciliaris an increase, with increasing WTR application rate , but for all treatments the differences were non-significant. The pH and EC of the leachates generally increased with increasing WTR addition. The concentration of nutrients in the grasses did not indicate any deficiencies or toxicities. As the growth of grass was poor in the ash treatments, another pot experiment was established to test the growth of two creeping grass species grown in the Rand WTR as a cover over the ash material. Cynodon dactylon and Stenotaphrum secundatum were grown in 20, 40 and 60 mm layers of Rand WTR, with and without a fertiliser treatment. Both species performed best in the 60 mm layer with fertiliser, and C. dactylon performed better than S. secundatum. The former species was more tolerant of the high pH, but both have potential as cover vegetation on the ash dumps when these are covered with Rand WTR. A further glasshouse study investigated the effect of Faure WTR mixed with a nutrient poor sandy soil on the nutrient uptake and seed yield of common dry beans (Phaseolus vulgaris). The WTR was added to the soil at 0, 50, 100, 200 and 400 g kg" each with five levels of fertiliser (0, 25, 50, 100 (recommended optimum) and 150 %). Bean pods were harvested once the plants had senesced. The number of pods and mass and number of seeds per treatment were determined. The seeds were analysed for nutrient uptake. Interveinal chlorosis and necrotic lesions were evident on cotylendonous and new leaves in the WTR treated soils, the severity of the symptoms increasing with increasing rate of WTR. Additional pots were established at the 400 g kg" rate (without fertiliser) and leaf material collected for chemical analysis. This showed that Mn toxicity was the cause, with leaf concentrations about 12 times the recommended 100 mg kg" upper limit. However, mass of bean seed was highest in the 400 g kg" Faure WTR treatment with 150 % fertiliser. Nutrient translocation to the seed seemed to be relatively consistent regardless of treatment, with little accumulation ofMn. The data collected illustrated the range of conditions and types of WTRs produced in South Africa, and that in some instances these residues have favourable characteristics for land application. The use of the Rand WTR showed that it could be applied to the spoil medium at relatively high concentrations without severely negatively impacting on grass growth, but more caution should be used when applying this material to the soil medium. While the grass did not grow in the ash treatments, it would seem that with suitable species the Rand WTR could be beneficially applied to ash material as a cover layer. The use of the Faure WTR on a sandy soil seemed to potentially improve the yield of the indicator crop, but caution should be exercised due to the possibility of Mn toxicity. The use of additional fertiliser would seem to be essential. Further research would require that field scale investigation of both WTRs be conducted, as well as further studies of applicat ion rates and techniques in laboratory and glasshouse investigations. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

Water treatment residues (WTRs) are the by-product from the production of potable water. They consist mainly of the precipitated hydrous oxides of the treatment chemicals, and materials removed from the raw water. This study investigated the range of treatment processes and residues produced in South Africa, and two WTRs were selected for testing on selected soils and mine materials. A questionnaire was developed and sent to water treatment authorities across South Africa. Information on the treatment chemicals, dosages, volumes and current disposal practices, and a sample of WTR from each treatment plant were requested. Eleven, of 21 authorities, returned completed questionnaires, representing 37 water treatment facilities. Organic polymers were the most commonly used treatment chemical, with most plants also using lime. Other less frequently used chemicals and additives were A12(SO4)3.14H2O, Fe2(SO4)3, FeC1), sodium aluminate, activated silica, activated charcoal, CO2 and bentonite. Information given regarding residue thickening and disposal was poor. Samples from Rand Water, Umgeni Water (Midmar), Midvaal Water Company, Amatola Water and Cape Metropolitan Council (Faure) were received or collected. An additional sample from Faure was also received, representing a change in the treatment process. These samples were analysed for a range of chemical and physical characteristics. These analyses showed that the WTRs had the potential to supply some plant nutrients (Ca, Mg, Fe, S) but that metal toxicity may be a problem, in particular Mn in the Faure WTR, and that P adsorption may be severe. The samples selected to test the potential for land disposal were from Rand Water and Faure. A pot experiment tested the growth of Eragrostis teff, Cenchrus ciliaris and Digitaria eriantha in mixtures of Rand WTR and material from a coal mine i.e., a sandy soil material, spoil material and coal combustion ash, at rates of 0, 50, 100, 200 and 400 g kg-1 with a uniform fertiliser treatment applied to all mixtures. The grass was harvested on three occasions and the mean total yield (dry mass) determined, as well as nutrient uptake. The pots were leached after each harvest and the pH and electrical conductivity determined. The soil, spoil and ash were characterised and pH, EC and water retention characteristics of the mixtures determined. Growth of the grasses in the ash treatments was poor and these were terminated. Eragrostis teff grown in the soil showed a decrease in mean total yield with increasing WTR application rate, but yield was good up to the 200 g kg-1 treatment at the first harvest, declining substantially by the second harvest. In general C. ciliaris and D. eriantha grown in the soil showed a decrease in mean total yield for all harvests with increasing WTR application. The yield of E. teff, grown in the spoil, increased up to 100 g kg-1 WTR addition, but decreased thereafter. Digitaria eriantha showed a decrease in yield, and C.ciliaris an increase, with increasing WTR application rate, but for all treatments the differences were non-significant. The pH and EC of the leachates generally increased with increasing WTR addition. The concentration of nutrients in the grasses did not indicate any deficiencies or toxicities. As the growth of grass was poor in the ash treatments, another pot experiment was established to test the growth of two creeping grass species grown in the Rand WTR as a cover over the ash material. Cynodon dactylon and Stenotaphrum secundatum were grown in 20, 40 and 60 mm layers of Rand WTR, with and without a fertiliser treatment. Both species performed best in the 60 mm layer with fertiliser, and C. dactylon performed better than S. secundatum. The former species was more tolerant of the high pH, but both have potential as cover vegetation on the ash dumps when these are covered with Rand WTR. A further glasshouse study investigated the effect of Faure WTR mixed with a nutrient poor sandy soil on the nutrient uptake and seed yield of common dry beans (Phaseolus vulgaris). The WTR was added to the soil at 0, 50, 100, 200 and 400 g kg-1 each with five levels of fertiliser (0, 25, 50, 100 (recommended optimum) and 150 %). Bean pods were harvested once the plants had senesced. The number of pods and mass and number of seeds per treatment were determined. The seeds were analysed for nutrient uptake. Interveinal chlorosis and necrotic lesions were evident on cotylendonous and new leaves in the WTR treated soils, the severity of the symptoms increasing with increasing rate of WTR. Additional pots were established at the 400 g kg-1 rate (without fertiliser) and leaf material collected for chemical analysis. This showed that Mn toxicity was the cause, with leaf concentrations about 12 times the recommended 100 mg kg-1 upper limit. However, mass of bean seed was highest in the 400 g kg-1 Faure WTR treatment with 150 % fertiliser. Nutrient translocation to the seed seemed to be relatively consistent regardless of treatment, with little accumulation of Mn. The data collected illustrated the range of conditions and types of WTRs produced in South Africa, and that in some instances these residues have favourable characteristics for land application. The use of the Rand WTR showed that it could be applied to the spoil medium at relatively high concentrations without severely negatively impacting on grass growth, but that more caution should be used when applying this material to the soil medium. While the grass did not grow in the ash treatments, it would seem that with suitable species the Rand WTR could be beneficially applied to ash material as a cover layer. The use of the Faure WTR on a sandy soil seemed to potentially improve the yield of the indicator crop, but caution should be exercised due to the possibility of Mn toxicity. The use of additional fertiliser would seem to be essential. Further research would require that field scale investigation of both WTRs be conducted, as well as further studies of application rates and techniques in laboratory and glasshouse investigations. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

The biological treatment of wastewater has evolved significantly from simple single sludge systems practicing organic carbon removal to ones which now include either nitrification/denitrification (N/DN) and / or phosphorus (P) removal. The inclusion of more biological processes have increased the complexity of current wastewater systems which has subsequently led to the development of more complex mathematical models. The operation of plants can be assessed and improved by the use of mathematical modelling tools which require accurate input data. Thus, knowledge of the wastewater characteristics is an important step towards the optimum modelling, design and operation of present and future plants. However, for these tools to be effective, the input data needs to be accurate which is dependent on the current methods used to determine them. Wastewater is a complex substrate consisting of compounds of differing biodegradability. Biokinetically, these compounds have been divided into readily biodegradable (RBCOD), slowly biodegradable (SBCOD) and unbiodegradable substrate groups. Compounds with intermediate biodegradability i.e. compounds which fall between the RBCOD and SBCOD groups, have been termed readily hydrolyzable organic substrates (RHCOD). The organic matter is discussed in terms of chemical oxygen demand (COD). The readily biodegradable and readily hydrolyzable COD fractions of wastewater can be determined by respirometric tests such as the oxygen utilization rate (OUR) and nitrate-N utilization rate (NUR) tests. The principal aim of this project was to investigate the NUR test as a tool for wastewater characterization and to study denitrification kinetics in batch reactors. In addition, an experimental readily biodegradable substrate, acetate, was used to determine the reliability of the NUR tests. Acetate was also used to ascertain utilization profiles and rates of a typical readily biodegradable substrate during denitrification. Biodegradable COD characterizations with enhanced biological phosphorus removal (EBPR) sludges were also investigated to determine the impact of anoxic phosphorus removal on NUR tests. The results obtained from the numerous NUR tests added to the undestanding of the NUR test. Samples from 22 wastewater treatment plants were tested, most of which were located in France. Four South African plants were also tested. Data obtained from the NUR tests were used to calculate the RBCOD and RHCOD fractions. The SBCOD, however, could not be determined directly from the 6 h NUR batch tests. The readily biodegradable COD (RBCOD) fractions ranged between 7 and 25 % of the total COD concentration of raw wastewater, with majority of those results falling within the 10-20 % (of the total COD) range. The results also showed that the initial rapid rate associated with readily biodegradable COD utilization was sometimes followed by a short intermediate phase (i.e. short duration, 2 to 3 h). The intermediate fraction was found to range between 5 and 29 % of the total COD concentration and was classed as a readily hydrolyzable COD component of raw wastewater since the magnitude of the RHCOD fraction was too small to be classed as slowly biodegradable COD which comprises approximately 30 to 60 % of the total COD found in raw wastewaters. The variability of the RHCOD fractions suggests that this fraction is either very variable or that the NUR test does adequately or accurately characterize it. Another possibility is that the RHCOD (or second biodegradable fraction) calculated from the NUR test is a component of the RBCOD of the influent wastewater. In this case, the bacteria may have used some of the RBCOD directly for energy and accumulated or stored the rest as part of a survival mechanism which allows them to be more competitive under dynamic operating conditions. Once the readily biodegradable COD becomes limiting, the bacteria will use the accumulated or stored compounds. This hypothesis is substantiated by tests done with acetate as substrate. An intermediate phase was also observed when acetate was the sole substrate. Thus, it was possible with the 3-phase profiles to calculate a second biodegradable fraction. Results suggest that a significant part of the added acetate (as COD) was stored and the second phase is in fact an 'apparent or residual' phase brought about by the consumption of the stored or accumulated acetate products. This is suggested in two ways: (1) the calculation of the yield coefficient is lower and closer to the 0.5 mg/l values, cited in the literature, when the COD calculated from phases 1 and 2 are considered, and (2) the acetate mass balances were found to be approximately 100 % when phases 1 and 2 were used to calculate the amount of acetate utilized under anoxic conditions. The results obtained with sodium acetate as a readily biodegradable substrate were used to formulate several conclusions on acetate utilization during denitrification. Firstly, from acetate mass balances it was found that acetate may be used exclusively for denitrification (100 % acetate was accounted for). In this case, the sludge contains a significant proportion of denitrifiers and little or no polyphosphate accumulating organisms. This observation was made only when non-EBPR (enhanced biological phosphorus removal) sludges were used. Secondly, acetate mass balances which were found to be < 100 % suggest that acetate could be used for denitrification and the production of storage products like polyhydroxyalkanoates (PHA's). These sludges probably contained a higher proportion of polyphosphate accumulating organisms which competed for the available acetate in the bulk liquid. This observation was made for both EBPR and non-EBPR sludges. Thirdly, acetate could be used for denitrification by denitrifiers and for polyhydroxyalkanoate synthesis by denitrifying polyphosphate accumulating organisms. The stored PHA's in the denitrifying polyphosphate accumulating organisms are subsequently utilized during denitrification. This secondary utilization is manifested in the second denitrification phase and is supported by the observation of phosphorus uptake. These results showed that wastewaters high in volatile fatty acids (VFA's) were also subject to denitrifying polyphosphate accumulating organism activity even though the sludge was sampled from non enhanced biological phosphorus removal systems (non EBPR). Several of the NOx profiles revealed either 2 or 3 rates due to the control of the substrate to biomass ratio (S/X: :<_0.1 mgO2 / mgO2). Majority of the samples (i.e. 85%) tested produced initial maximum specific denitrification rates (k1) between 3 and 6 mgN/gVSS.h. The intermediate denitrification rate (k2) was found to vary between 2 and 3 mgN/gVSS.h. Denitrification rates (k3) obtained from utilization of influent and. endogenous slowly biodegradable COD (SBCOD) varied between 1.0 and 1.5 mgN/gVSS.h. This latter rate is significantly higher than the endogenous denitrification rates cited in the literature. One of the reasons for these higher rates could be be linked to the the reuse of stored or accumulated products by the microorganisms. In addition, a comparative study on RBCOD determination of wastewaters with enhanced biological phosphorus removal and non-EBPR sludges. It was found that the RBCOD values derived by NUR tests with EBPR sludge were consistently lower (4 to 5 %) than those with non-EBPR sludge. Thus, the NUR tests with EBPR sludge resulted in a 4 to 5 % underestimation of the RBCOD fraction of raw wastewaters. This loss in RBCOD to polyphosphate accumulating organisms appears to be linked to the influent raw wastewater acetate concentration. These tests showed that the RBCOD fraction could be adequately characterized using the NUR method. The accuracy of the tests appears to be compromised when enhanced biological phosphorus removal sludges are used in the NUR tests. Moreover, it was found that non-EBPR sludges can also consume some of the acetate that is present in the system for the production and replenishment of storage compounds. Fortunately, for the wastewaters tested, the acetate component of the RBCOD fraction was small and therefore, did not significantly affect the results. Mechanisms such as substrate accumulation and storage may also impact on substrate removal and hence, the determination of the readily biodegradable COD concentration of municipal wastewaters. Thus, while the results showed that the NUR is a useful characterization tool for wastewaters, it will continue to be a more tedious characterization tool than the oxygen utilization rate test, until a suitable nitrate/nitrite electrode is developed to automate the test. / Thesis (Ph.D.)-University of Natal, Durban, 1999.

Baigiamajame magistriniame darbe tirta Utenos nuotekų valymo įrenginių pirminio ir perteklinio veikliojo dumblo mišinio skirtingų polimerų ir geležies druskų anaerobiniam puvimo procesui įtaka. Analizėje nagrinėjama proceso metu išsiskiriančių biodujų tūris ir metano dujų koncentracija. Tyrime naudojamas anaerobinio pūdymo modelis „W8 Armfield Ltd“, kuris dirba kaip vienalaipsniai anaerobiniai reaktoriai su mezofiliniu režimu. Išbuvimo trukmė – 20 dienų, apkrova bepelenėmis sausomis medžiagomis (BSM) nuo 0,61–0,96 gBSM/l/d, tiekiamo dumblo mišinio sausų medžiagų kiekis (SM) – 4 %. Baigiamuoju darbu siekiama išanalizuoti dumblo tirštinimui naudojamo sintetinio arba natūralaus polimero ir dozuojamos druskos (geležies sulfato (Fe2(SO4)3) bei geležies chlorido (FeCl3)) įtaką anaerobiniam pūdymo procesui. Panaudojus anaerobinio pūdymo modelį buvo sukurtos anaerobinės sąlygos ir pūdomas iš Utenos nuotekų valyklos tiekiamas pirminio ir perteklinio dumblo mišinys. Naudojantis įrenginiu INCA 4000 T100 buvo kaupiamos biodujos ir analizuojama jų sudėtis. Darbe taip pat nagrinėjamas SM sumažėjimas ir BSM suskaidymas. Įvertinus visus analizuojamus kriterijus nustatomas efektyviausias metodas išsiskiriančių dujų efektyvumui ir kokybei pagerinti. Išanalizavus tyrimo rezultatus pateiktos išvados. Darbą sudaro šios dalys: įvadas, 4 skyriai, išvados, rekomendacijos, literatūros sąrašas. Darbo apimtis – 63 p. teksto be priedų, 32 paveikslai, 8 lentelės, 42 bibliografiniai šaltiniai. / Objective of this work was to investigate impact of different iron and polymer doses on anaerobic digestion process. Primary and waste activated sludge was obtained from Utena Wastewater treatment plant. Analysis shows the volume of biogas produced and percentage of methane. The work was carried out using high-rate anaerobic digestion model W8 (Armfied Ltd. UK) which operates in the mesophilic range. The solids retention time was 20 days. The volatile suspended solids loading rate ranged from 0.61 to 0.96 g VSS/l d.Sludge mixture feed concentration – 4%. The Purpose of this work is to analyse impact of synthetic and organic polymer also iron (III) sulphate (Fe2(SO4)3) and iron (III) chloride (FeCl3) on anaerobic digestion process. Primary and waste activated sludge was obtained from Utena Wastewater treatment plant. The biogas was collected and components were analysed using INCA 4000 T100 analyser. Analysis of TS reduction and VS destruction is also presented. The most effective method of improving off-gas efficiency and quality was determined considering all the criteria determined by analysis. Having analyzed the results of the research, conclusions have been made. This work consists of the following parts: pre-face, 3 sections, conculsions, recommendations, reference list. There are 63 pages of text without appendices, 32 figures, 8 tables and 42 bibliographical sources in this work.

Bioflocculation, which can be defined as aggregation of bacterial flocs, has important implications on the physical characteristics of sludge. It is especially critical to settling and dewatering systems which impacts the overall economy of the process greatly. One of the most common problems in activated sludge systems to negatively influence the settleability is sludge bulking which can be defined as non-settling situation of microbial mass. The first objective of this research is to investigate the effect of calcium ion on sludge bulking in a phosphorus deficient medium and the second objective is to improve the settling, dewatering, and pumping of activated sludge by adjusting the calcium (Ca) ion concentration of the feed. For this purpose, 7 semi-continuous laboratory scale activated sludge reactors were operated with a mixed aerobic culture. The reactors had 8 days of sludge residence time and aerated with air pumps to provide a dissolved oxygen concentration of at least 3 mg/L. All the analyses were conducted after the reactors reached steady state condition. In the first part of the research, the effect of strictly phosphorus-limited medium on bulking of activated sludge was studied at different calcium ion concentration. Three reactors were set up having 5, 10 and 20 meq/L calcium concentrations. From the results it was observed that, phosphorus deficiency caused viscous bulking independent from the calcium ion concentration. It was found out that bulking of activated sludges due to phosphorus deficiency could be cured by the addition of phosphorus. Furhermore, microorganisms starved for phosphorus, seemed to accumulate polyphosphate granules when they were exposed to a phosphorus source. In the second part of the study, the effect of calcium ion on physical, chemical and surface chemical properties of activated sludge was investigated at 4 different concentrations (0.27, 5, 10 and 20 meq/L) under sufficient phosphorus concentration. Calcium addition resulted in significant changes in the quantity and quality of extracellular polymeric substances (EPS). Total EPS increased depending on the calcium concentration. Carbohydrate content of EPS dominated over the protein content for calcium concentration of 5 meq/L and above. The amount of calcium ions incorporated into the sludge floc matrix also increased with the dose of calcium added. Settleability and dewaterability of sludge improved significantly at 5 meq/L dose of calcium. However, settleability did not change any further with increasing calcium dose, whereas dewaterability increased for all increasing calcium concentrations. Sludge viscosity also decreased considerably at 5 meq/L concentration indicating better pumpability but it did not change further above 10 meq/L calcium addition.

Activated sludge systems are the most widely used biological wastewater treatment processes all over the world. The main working principles of an activated sludge system are the oxidation of biologically degradable wastes by microorganisms and the subsequent separation of the newly formed biomass from the treated effluent. Separation by settling is the most troublesome stage of an activated sludge process. A decrease in the efficiency of the separation of microbial biomass from the treated effluent causes a decrease in the overall efficiency of the treatment plant. The efficiency of the separation process is related to the bioflocculation, which can be briefly defined as the aggregation of the bacteria into flocs through flocculation. Bioflocculation depends on the extracellular polymers (EPS) that are produced by microorganisms. The operating conditions of the activated sludge system is a key determinant of the synthesis of EPS and bioflocculation. The main objective of this study is to find out the effect of magnesium ions on the bioflocculation process under phosphorus deficient and sufficient conditions. In order to achieve this aim, the effects of magnesium ion in 4 different concentrations (0.9, 5, 10 and 20 meq/L) are investigated in semi continuous reactors. The reactors are operated at a mean cell residence time of 8 days and 20&ordm / C temperature. When reactors are confirmed to be at steady state, several sets of analysis are conducted. In particular, the surface chemical parameters including EPS and its components, electrical charge, and hydrophobicity as well as physical properties such as settlability, filterability, viscosity, floc strength, and turbidity are examined. It has been understood that phosphorus deficiency causes severe filamentous bulking under magnesium rich conditions. Increasing the phosphorus concentration in the influent can cure this problem. After the sludges are cured some granular structures were observed in the microscopic investigations and they are thought to be polyphosphate granules in which microorganisms tend to accumulate phosphorus when they find the adequate source after a starvation period. To consider the reactors operated at phosphate present conditions, it has been found that EPS increases with increasing influent magnesium concentration. However, protein type EPS (EPSP) exhibits a sharper increase when compared to the carbohydrate type EPS (EPSC) indicating the selective attitude of magnesium ions to protein type of polymers. It has been understood that the increase in the influent magnesium concentration results in an increase in dewaterability and zone settling velocity, and a decrease in the viscosity. Hydrophobicity was found to exhibit a maximum value at 10 meq/L magnesium fed sludge and then it dropped back. Surface charge values also made a minimum at 10 meq/L reactor and then no change occurred at the increase of the magnesium concentration to 20 meq/L. Finally, COD values were found to increase with the increasing magnesium concentration due to the increasing EPS.

Thesis (MSc Food Sc )--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The potential use of the upflow anaerobic sludge blanket (UASB) bioreactor is limited by the extended start-up periods due to the time-consuming granulation process and the fact that seeding inoculum is not freely available in most developing countries like South Africa. The mass cultivation of granules would provide the waste water treatment industry with suitable seeding inoculum and, therefore, an efficient waste water treatment option would be more easily available. By applying 'stress' conditions on a bioreactor system seeded with raw anaerobic sludge, the population dynamics of the anaerobic community change and the acidogens start to produce extracellular polymers, which in turn enhance the granulation process by providing a matrix for the bacterial cells to adhere to. These "environmental stress" conditions include changes in the C:P:N ratio's. The aim of this study was, therefore, to assess the impact of different carbon and nitrogen sources on the enhancement of granulation in a batch system, and to determine the best preservation technique in terms of retainment of activity. It was found that the carbon source and concentration had a significant influence on batch granule enhancement. Low concentrations (2.g.l ̄ ¹) of glucose gave the best granule enhancement over a 14 day incubation period. Fruit cocktail effluent was found to be a cheap and effective carbon source for batch granule cultivation. It was found that different nitrogen sources did not have the same impact on granule enhancement, however, urea, at all concentrations tested, gave the best granule enhancement. A major problem encountered during the study was the standardisation of the inoculum. Significant granule enhancement comparisons between the different carbon sources were impeded by the lack of a suitable and reliable form of sludge standardisation. Future research needs to address this problem of the standardisation of the sludge inoculum as this would lead to more kinetically comparable results. Mass granule culturing will require granule preservation without risking the loss of activity. In the second study, six different preservation techniques and storage periods were evaluated in terms of the retainment of activity. These involved freeze-drying, vacuum freeze-drying, vacuum-drying, freezing, cold storage and room temperature preservation. Activity testing was used for comparing the efficiency of the different preservation techniques in terms of the tempo of biogas and methane production. Freeze-drying the granules, with storage for up to 90 days was found to give the best retainment of activity, followed by vacuum freeze-drying. The room temperature preserved samples showed a sudden increase in activity by day 120, which could possibly be explained by cell hydrolysis of the granules after day 90. The highest activity was achieved after 10 h of incubation, and it was, therefore, suggested that activity testing for evaluation purposes should use an incubation time of only 10 h. Furthermore, only the basic test medium with added glucose should be used for activity testing as it was observed that the addition of lactate and acetic acid played no decisive role in determining the level of activity of the granules. This study recommends the use of low concentrations of glucose for optimum granule enhancement during the mass cultivation of granules, and the addition of low concentrations of lactate to ensure a stable system with no acidification. It is also advisable to use a standardised sludge inoculum, as this will allow more efficient comparisons. Freeze-drying is recommended as preservationtechnique as this technique showed the best retainment of activity. A storage period of 90 days is, however, too short to be of much use for the industry. This will have to be investigated, together with the phenomenon of increased activity after 90 days as shown by the room temperature preserved granules. / AFRIKAANSE OPSOMMING: Die potensiële gebruik van die "uptflow anaerobic sludge blanket" (UASB) bioreaktor word beperk deur verlengde aansitprosedure as gevolg van die tydsame granulasieproses en die feit dat geskikte inokulums nie vrylik beskikbaar is in die meeste ontwikkelende lande, bv. Suid-Afrika nie. Die massa-kweking van granules sal die afvalwater-industrie voorsien van 'n geskikte inokulum, en sodoende 'n effektiewe opsie vir die behandeling van afvalwater beskikbaar stel. Deur die aanwending van "stres" toestande op 'n reaktor, wat geinokuleer is met rou anaerobe slyk, vind daar 'n verandering in die samestelling van die anaerobe populasie plaas. Die laktaat-benuttende asidogene begin om ekstrasellulêre polisakkariede te produseer wat die granulasieproses versnel deur 'n matriks te voorsien waaraan die bakteriële selle kan heg. Hierdie "omgewings stres" toestande sluit veranderinge in die C:P:N verhoudings in. Die doel van hierdie studie was om die invloed van verskillende koolstof- en stikstofbronne op die vermeerdering van granules te bepaal, asook om die beste preserveringstegniek in terme van die behoud van aktiwiteit te bepaal. Daar is gevind dat die koolstofbron en konsentrasie 'n betekenisvolle invloed op granule-vermeerdering het. Lae konsentrasies glukose (2 g.I ̄ ¹) het tot die grootste vermeerdering in granules oor 'n 14 dae inkubasieperiode gelei. Vrugtekelkie-afvalwater is geidentifiseer as 'n goedkoop en effektiewe koolstofbron wat ook gebruik kan word vir die kweking van granules. Voorts is gevind dat die stikstofbron en konsentrasie nie so 'n groot invloed op granule-vermeerdering het nie. Urea het nietemin die beste granule-vermeerdering vir al die konsentrasies wat getoets is, gegee. Standaardisasie van die inokulum was 'n groot probleem gedurende die studie. Betekenisvolle vergelykings tussen die granule-vermeerderings verkry met die verskeie groeimedia is bemoeilik deur die afwesigheid van 'n geskikte en betroubare standaardisasie-metode. Toekomstige navorsing moet hierdie probleem aanspreek aangesien dit sal lei tot meer kineties vergelykbare resultate. Massa-kweking van granule sal 'n metode van granule-preservering vereis sonder enige verlies van aktiwiteit. In die tweede studie is ses verskillende preserverings-tegnieke en opbergings-periodes in terme van die behoud van aktiwiteit geëvalueer. Die tegnieke sluit in: vriesdroging; vakuum-vriesdroging; vakuumdroging; bevriesing; koelopberging en kamertemperatuur-preservering. Aktiwiteitstoetsing is gebruik vir die vergelyking van die effektiwiteit tussen die verskillende preserverings-tegnieke in terme van die tempo van biogas- en metaanproduksie. Die granules wat met behulp van die vriesdroogtegniek gepreserveer is, het die beste behoud van aktiwiteit getoon, gevolg deur die vakuum-gevriesdroogde granules. Die monsters wat by kamertemperatuur gepreserveer is, het 'n skielike toename in aktiwiteit na 120 dae van opberging getoon en 'n moontlike verklaring vir hierdie verskynsel kan sel-hidrolise van die granules na 90 dae van opberging wees. Die meeste aktiwiteit is behaal na 'n 10 h inkubasietyd, en dus word hierdie inkubasietyd aanbeveel indien aktiwiteitstoetse vir evaluerings-doeleindes gedoen word. Verder word aanbeveel dat slegs die glukose-verrykte basiese toetsmedia vir aktiwiteitstoetsing gebruik word aangesien die byvoeging van laktaat en asynsuur geen noemenswaardige rol speel in die bepaling van die vlak van aktiwiteit van die granules nie. Hierdie studie beveel die gebruik van lae glukosekonsentrasies aan vir optimale vermeerdering van granules tydens die massakweking daarvan, asook die byvoeging van lae konsentrasies laktaat om 'n stabiele sisteem met geen versuring te verseker. Die gebruik van 'n gestandaardiseerde slyk-inokulum word sterk aanbeveel aangesien dit meer vergelykbare resultate lewer. Vriesdroging (as preserveringstegniek) het die beste behoud van aktiwiteit in die granules getoon en word dus as preserveringstegniek aanbeveel. 'n Opbergingsperiode van 90 dae is egter te kort om van veel waarde vir die industrie te wees. Hierdie probleem, asook die verskynsel van 'n verhoging in aktiwiteit na 90 dae van die granules wat by kamertemperatuur gepreserveer is, moet verder ondersoek word.

Made available in DSpace on 2016-06-02T20:00:45Z (GMT). No. of bitstreams: 1 4632.pdf: 8984815 bytes, checksum: 8d68f51689a782923b2bcfbb5000f4a3 (MD5) Previous issue date: 2012-05-21 / Financiadora de Estudos e Projetos / Substances in Sewage Sanitary exert deleterious effects on bodies of water; the organic matter which is present may cause a decrease in concentration of dissolved oxygen, killing fish and other aquatic organisms, eutrophication by the presence of nutrients causing an accelerated growth of algae that give odor, taste and biotoxins to the water,darkening and siltation of the watercourse. In this scenario, it is of great importance the need for sewage treatment. However, in the treatment process, occurs the production of sludge rich in organic matter and nutrients, known as sewage sludge. This residue at the end of the treatment process should receive special attention, requiring proper disposal. Moreover, it is found that several sewage treatment projects do not include the final destination of the sludge that is produced, which results in the partial annulment of the benefits of collecting and treating collected wastewater. Therefore, this study presents results of analyzes performed on sludge from sewage treatment contained in BAG's of Geotextile Blanket of ETE-Limoeiro / SABESP, located in the city of Presidente Prudente, SP. The objective of this work was to characterize the physico-chemical and microbiological parameters in accordance with Resolution N° 375/06 of Conselho Nacional do Meio Ambiente CONAMA, and evaluate the efficiency of dewatering of sludge. Based on this, the analysis of identification and quantification of heavy metals showed values below the maximum allowed concentrations in sludge. Regarding the assessment of macro and micronutrients, analysis showed that the sludge has significant amounts of essential nutrients to the soil and plants and it can be used for this purpose after specific treatment. Regarding the biological tests for quantification of fecal coliforms, the obtained concentrations showed values that were established for the sludge Class B. The sludge was also evaluated for stability using the relation between volatile solids and total solids. This relation presented results for SV/ST below 0.70 which allowed defining the sludge as stable according to Resolution 375/06. However, the evaluation of the water removal process showed commitment of the dewatering efficiency according to the characteristics of the sludge generated in the Sewage Treatment Plant. Geotêxtil da ETE-Limoeiro / SABESP, localizada no Município de Presidente Prudente-SP. O objetivo central desta pesquisa foi à caracterização dos parâmetros físico-químicos e microbiológicos em conformidade com a Resolução Nº 375/06 do Conselho Nacional do Meio Ambiente CONAMA, e a avaliação da eficiência do processo de remoção de água dos lodos. Ante o exposto, as análises para identificação e quantificação de metais pesados apresentaram valores abaixo das concentrações máximas permitidas em lodos. Em relação à avaliação de macro e micronutrientes, as análises demonstraram que o lodo possui quantidades significativas de nutrientes essenciais aos solos e plantas, podendo ser utilizado para esta finalidade após tratamento específico. Referente às análises biológicas para quantificação de coliformes termotolerantes, as concentrações obtidas apresentaram valores estabelecidos para lodos Classe B. Os lodos também foram avaliados quanto à estabilidade através da relação entre sólidos voláteis e sólidos totais. Esta relação apresentou resultados para SV/ST inferiores a 0,70 permitindo definir os lodos como estáveis de acordo com a Resolução 375/06. Entretanto, avaliação do processo de remoção de água, demonstrou comprometimento da eficiência do desaguamento em função das características do lodo gerado na Estação de Tratamento de Esgotos. / As substâncias presentes nos esgotos sanitários exercem ação deletéria nos corpos de água, a matéria orgânica presente pode causar a diminuição da concentração de oxigênio dissolvido provocando a morte de peixes e outros organismos aquáticos, eutrofização pela presença de nutrientes provocando o crescimento acelerado de algas que conferem odor, gosto e biotoxinas á água, escurecimento e assoreamento do curso d água. Diante deste cenário, é de suma importância a necessidade do tratamento dos esgotos. Porem no processo de tratamento ocorre à produção de um lodo rico em matéria orgânica e nutriente, denominado lodo de esgoto. Este resíduo ao final do processo de tratamento deve receber uma atenção especial, necessitando de adequada disposição final. Contudo, constata-se que geralmente vários projetos de tratamento de esgotos não contemplam o destino final do lodo produzido, acarretando assim na anulação parcial dos benefícios da coleta e do tratamento dos efluentes coletados. Neste sentido, esta pesquisa apresenta resultados de análises realizadas em lodos de estação de tratamento de esgoto contidos em BAG´s de Manta Geotêxtil da ETE-Limoeiro / SABESP, localizada no Município de Presidente Prudente-SP. O objetivo central desta pesquisa foi à caracterização dos parâmetros físico-químicos e microbiológicos em conformidade com a Resolução Nº 375/06 do Conselho Nacional do Meio Ambiente CONAMA, e a avaliação da eficiência do processo de remoção de água dos lodos. Ante o exposto, as análises para identificação e quantificação de metais pesados apresentaram valores abaixo das concentrações máximas permitidas em lodos. Em relação à avaliação de macro e micronutrientes, as análises demonstraram que o lodo possui quantidades significativas de nutrientes essenciais aos solos e plantas, podendo ser utilizado para esta finalidade após tratamento específico. Referente às análises biológicas para quantificação de coliformes termotolerantes, as concentrações obtidas apresentaram valores estabelecidos para lodos Classe B. Os lodos também foram avaliados quanto à estabilidade através da relação entre sólidos voláteis e sólidos totais. Esta relação apresentou resultados para SV/ST inferiores a 0,70 permitindo definir os lodos como estáveis de acordo com a Resolução 375/06. Entretanto, avaliação do processo de remoção de água, demonstrou comprometimento da eficiência do desaguamento em função das características do lodo gerado na Estação de Tratamento de Esgotos.

Orientador: Roberto Alves de Oliveira / Banca: Wanderley José de Melo / Banca: Marco Antonio Penalva Reali / Resumo: Nas estações de tratamento de água (ETA), as impurezas retiradas da água juntamente com os produtos hidrolisados dos coagulantes dão origem aos resíduos dos decantadores e das águas de lavagem dos filtros, denominados lodo de ETA. Neste experimento, foi avaliado a disposição de lodo de ETA em reatores anaeróbios de fluxo ascendente com manta de lodo (UASB), com volume de 18 L e 38 L, visando o tratamento para destinação adequada do efluente e do lodo excedente dos reatores. Tal experimento foi dividido em quatro ensaios, com tempo de detenção hidráulica de 24 h nos reatores UASB, previamente inoculados com lodo granulado e floculento. Foram observadas condições em que foram aplicadas ao reator UASB, lodo de ETA, com DQOtotal de 161 mg/L e ST de 1.948 mg/L, e misturas de lodo de ETA com esgoto sanitário nas seguintes proporções, em volume, de 1:1 (lodo de ETA : esgoto sanitário) com DQOtotal de 458 mg/L e ST de 3.039 mg/L; 1:3, com DQOtotal de 519 mg/L e ST de 1.562 mg/L e 1:7, com DQOtotal de 1.174 mg/L e ST de 3.502 mg/L. Os valores médios de eficiência de remoção da DQOtotal foram de 75 a 83% e de ST de 73 a 87%. A maior remoção de P foi de 90% e de N de 41%. As eficiências de remoção de Ca, Co, Fe, Mn, Ni, Cu, Pb, Cr e Zn foram superiores a 70%, confirmando a alta capacidade de bioadsorção de metais do lodo anaeróbio. As concentrações de N-am, Fe, Mn, Ni, Cd, Pb, Cu, Cr e Zn atenderam aos padrões de lançamento de efluentes da legislação federal. Ocorreram remoções de E. coli acima de 90%, resultando contagens do efluente de 1,5x10 UFC/100 mL, apresentando qualidade microbiológica correspondente à água doce de classe 1, conforme os padrões estabelecidos na Resolução CONAMA 357/2005 . O lodo do reator UASB apresentou valores de relação SV/ST e E. coli que permitiram o seu uso na agricultura. / Abstract: In water treatment plants (WTP), impurities removed from water mixed with coagulative hydrolytic product create waste of decanters and launderings water filters residues called WTP sludge. In this experiment the WTP sludge disposal in an Upflow Anaerobic Sludge Blanket Reactor (UASB) were evaluated, with a volume of 18 L and 38 L, aiming treatment for appropriate disposal of effluent and excess sludge reactors. Such experiment was divided into four assays, with hydraulic detention time of 24 h in UASB reactors by being inoculated previously with flocculent and granular sludge. It was observed conditions in wich it was added to the UASB reactor WTP sludge with CODtotal of 161 mg/L and TS of 1,948 mg/L, and mixtures of WTP sludge and wastewater in the following amounts, in volume, 1:1 (WTP sludge : wastewater) with CODtotal of 458 mg/L and TS of 3,039 mg/L; 1:3 with CODtotal of 519 mg/L and TS of 3,382 mg/L and 1:7 with CODtotal of 1,174 mg/L and TS 3,501 mg/L. The average values of removal efficiency of CODtotal were 75 the 83% and TS 73 the 87%. The highest P removal was 90% and the highest one of N was 41%. Removal efficiencies of Ca, Co, Fe, Mn, Ni, Cu, Pb, Cr and Zn were higher than 70% wich confirmed the high capacity of biosorption and bioaccumulation of metals from anaerobic sludge. Concentrations of Nam, Fe, Mn, Ni, Cd, Pb, Cu, Cr and Zn fit the quality standards of effluent discharge required by federal legislation. There were removals of E. coli higher than 90% which resulted in counts for effluent of 1.5x10 CFU/100 mL and it showed microbiological quality corresponding to freshwater class 1, according to the standards established in CONAMA Resolution 357/2005. Sludge from the reactor showed ratios of VS /TS and E. coli which allows agricultural use. / Mestre