Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A poluição dos corpos dágua proveniente dos efluentes têxteis provoca alterações em ciclos biológicos afetando principalmente a fotossíntese. Além disso, algumas classes de corantes podem ser carcinogênicos e/ou mutagênicos. Devido à dificuldade em se tratar estes efluentes, novas tecnologias têm sido investigadas. Neste contexto, a eletrofloculação surge com uma técnica promissora, devido à sua eficiência e possibilidade de reuso da água. O presente trabalho tem como objetivo estudar a aplicação do processo de eletrofloculação no tratamento de efluentes de uma indústria têxtil. O processo de eletrofloculação foi realizado em um reator de batelada utilizando eletrodos de ferro e alumínio. A influência dos seguintes parâmetros foi avaliada: natureza e distância do eletrodo, variação de pH, potencial elétrico aplicado e tempo de operação. Os resultados obtidos indicaram que o processo de eletrofloculação nas condições operacionais estudadas é uma alternativa tecnicamente viável para a remoção de DQO, cor e turbidez, a qual foi, respectivamente, de 87%, 95% e 100%. / The pollution of the stream waters through textille effluents causes alterations in biological cycles affecting the photosynthesis mainly. Moreover, some class of dyes can be carcinogenic and/or mutagenic. Due to difficulty in treating these effluents new technologies have been investigated. In the present work, electrofloculation appears to be a very promising technique, due to relatively high efficiency and possibility of water reuse. The present work emend has objective to study the application of electrofloculation in the treatment of effluents of a textile industry. The process was carried out in a batch reactor using electrodes either iron or aluminum. The influence of the following parameters was evaluated: nature and distance between electrodes, pH, electric potential applied and operation time. The results indicated that the process of electrofloculation in these operational conditions is a technical viable alternative for the removal of COD, color and turbidity, which were, respectively, of 87%, 95% and 100%.

WATREX is an expert system used to aid in potable water treatment plant design and was developed several years ago by the Water Research Commission. More recently, this system was tested and a number of deficiencies identified. Amongst these deficiencies were the list of possible chemicals that should be additionally included in the system, as well as the prediction of turbidity removal. The objectives of this project were to investigate and improve these deficiencies. This was achieved in two ways. The chemical addition deficiency was improved through the introduction of new chemicals as separate processes and via improved formulation to model the effects of these chemicals using a spreadsheet with automated calculation abilities. Turbidity removal prediction was improved by the mathematical modelling using data obtained from existing water treatment plants throughout South Africa. The results obtained from the chemical addition improvements were compared to those obtained from other models and found to be correct. The modelling of the turbidity removal data resulted in a series of equations that predict turbidity removal based on plant performance and incoming turbidity values, a first of its kind. Though complete, these models have yet to be incorporated into the existing WATREX system. / Prof. J. Haarhoff

A critical review of the mechanisms of present water treatment systems including, chlorination, coagulation, filtration, granular and powdered activated carbon adsorption, ozonation and ultraviolet radiation for the removal of herbicides is presented. Rapid selective and sensitive HPLC methods were developed and rigorously validated for the analysis of the selected herbicides. Analysis of atrazine was made using Cl8 cartridges. For raw water containing interferences, extraction of the compound was made on SCX cartridges, followed by solvent exchange on C18 cartridges. A quantitative recovery of virtually 100% of the compound was achieved using C18. While the double cartridge extraction of the compound gave a recovery of about 89%. Previously developed methods for 2,4-D and MCPA were rigorously validated for the extraction and analysis of 2,4-D and MCPA. A quantitative recovery of usually greater than 90% was achieved for both compounds using Cl8 cartridges. For the extraction of paraquat different extraction systems including, reversed phase on C8 and C18, ion-paired reversed phase on C18, and cation exchange on SCX, CBA, and CN were investigated. A quantitative recovery, usually greater than 90%, of the compound was obtained using CN and CBA cartridges. The methods were then successfully used for the evaluation of the removal efficiency and establishment of mechanisms of removal of herbicides by biological filters at bench and pilot scale. Four herbicides belonging to three broad chemical categories were studied. The data presented in this study demonstrated that biological filters are very efficient in removing certain classes of herbicides. 2,4-D and MCPA were consistently removed to below a detection limit of 0.1 mug/1 for an influent concentration of 3-11 mug/1. Process variables such as flow rate, bed depth and contact time were investigated for the efficient removal of these herbicides. Seasonal variations in performance were observed and possible explanations proposed. A series of experiments was undertaken to establish .mechanisms of removal. Quantitative recovery of the herbicides from the river water proved that the processes in the filter bed as opposed to the processes in the water were responsible for removal of the herbicides. It was clear from the investigation of the adsorption of the herbicides both on the sand and organic and inorganic dirt that adsorption on these surfaces was not the main reason for removal. Filter maturation experiment showed that the presence of microorganisms in the bed is a precondition for the removal of herbicides. A depth experiment for the removal of 2,4-D showed that superficial efficient zone of removal imitates the distribution of microbial density. This evidence confirms the significance of microorganisms for the removal of herbicides by the filter bed. The ultimate proof of the biodegradation of 2,4-D by microorganisms in the filter bed was the identification of the biodegradation product 2-chlorophenol as predicted by the metabolic pathways of the compound. Filter design modifications using activated carbon were made to accommodate the removal of 'non-biodegradable' herbicides. A sandwich sand / GAC / sand filter was investigated. Filter efficiency for this arrangement was determined and short-comings were identified and a possible solution in the form of a double GAC sandwich is suggested.

Reliable sensor values are important for resource-efficient control and operations of wastewater treatment processes. Automatic fault detection methods are necessary to monitor the increasing amount of data produced in any modern water resource recovery facility (WRRF). Most on-line measurements exhibit large variations under normal conditions, due to considerable variations in the influent flow. The work reported in this licentiate thesis deals with fault detection in WRRFs. In the first paper, we studied how Gaussian process regression (GPR), a probabilistic machine learning method, could be applied for fault detection in WRRFs. The results showed that the standard parameter estimation method for GPR suffered from local optima which could be solved by instead estimating the distribution of the parameters with a sequential Monte Carlo algorithm (GPR-SMC). The GPR-SMC allowed for automatic estimation of missing data in a simulated influent flow signal with high noise, which is a representative signal for on-line sensors in WRRFs. In addition, the GPR-SMC provided uncertainty predictions for the estimated data and accurate sensor noise estimates. Care should be taken in selecting a suitable kernel for GPR, since the results were in contrast to the general assumption that prior knowledge can easily be encoded by means of selecting a proper kernel. Here, the autocorrelation graph was found useful as diagnostic tool for selecting a proper kernel. In the second paper, we studied how active fault detection (AFD) could be used to reveal information about the sensor status. The AFD was implemented by evaluating the change in a dissolved oxygen (DO)-signal caused by the sensor's automatic cleaning system. Fault signatures were obtained for fouling and several other sensor faults such as a worn out or mechanically damaged membrane. This demonstrates the potential of AFD, not only for fault detection, but also for fault diagnosis. Interestingly, the progression of the sensor bias due to organic biofilm fouling differed depending on the measurement technique used within the DO-sensor. This is new knowledge that is valuable for process control and should be further studied. The AFD was implemented on a full scale system to demonstrate its applicability, which is rarely done in research papers in the field of WRRFs.

M. Ing.

Empirical observation of filter beds at South African water treatment plants showed that the filters were insufficiently cleaned by the backwash system and that media losses were unexpectedly high. Specific deposit tests developed by the RAU Water Research Group indicated that the dirtiness correlated with the organic content of the water being treated. This led to the hypothesis that biofilm is present on the media, somehow causing both the media loss and the difficulty to attain efficient backwashing. Biofilm consists of organisms surrounded by a sticky, gelatinous polysaccharide matrix. This matrix, also known as extra-cellular polymeric substances (EPS), is the bulk (50-90%) of the biofilm. Biofilm plays an important role in the establishment and maintenance of organisms in a hostile environment. From the above it doesn¡¦t make sense trying to measure biofilm from the numeration of the organisms. A more reliable direct but tedious measure is quantifying the EPS. A new alternative method developed by the RAU Water Research Group is to mechanically strip the specific deposit off the filter media and then determine the organic fraction by combusting the sample at 500¢XC. Two aspects of mechanical behaviour are deemed important in this study. First, headloss, because an under prediction in headloss will result in a higher than expected backwash frequency. Second, bed expansion, because an under prediction in bed expansion will lead to media washout. Literature indicates that both headloss and bed expansion increase with increasing biofilm growth. However, all those studies were conducted at waste water treatment plants with high organic and solids loading. With the exception of one reference which only discusses headloss, nothing on this topic is available in the literature for potable water treatment. Mathematical models were used to reduce the data from multiple headloss and bed expansion experiments. For the headloss data the Ergun equation was used and the sphericity (ƒÚ) was retained as the only unmeasured calibration constant. For the bed expansion data the Dharmarajah equation was used and the sphericity was retained as the only unmeasured calibration constant. Calibration of the mathematical models was done with least square fitting. The two values of sphericity as determined by Ergun and Dharmarajah are not necessarily the same for the same media sample. The sphericity was used as a calibration constant without any physical meaning, which accounts for different sets of complex unknowns. Samples for experimental work were drawn from full scale operating water treatment plants. The treatment plants were spread over four provincesof South Africa with different raw water sources, but using approximately the same media. The sampling was done on three occasions, Winter 2003, Summer 2003 and Winter 2004, to cover the extreme temperatures experienced in South Africa. Samples collected at the plants were tested for headloss and bed expansion, then transported back to the laboratory and placed in the oven for 24 hours at 110¢XC. The sample was then sieved and the density determined. The headloss and bed expansion tests were then repeated in the laboratory. Parallel to these tests, EPS and volatile fraction quantification tests were done. Direct methods of measuring biofilm, namely EPS and volatile fraction, yielded measurable results, thereby confirming the presence of biofilm. Plants that had large quantities of EPS also had a high volatile fraction, thereby confirming the expectation that the volatile fraction is an excellent method to rapidly quantify biofilm presence. EPS made up 41% of the volatile fraction, which is roughly comparable with the 50-90% quoted in literature. Where large quantities of EPS were found at a plant, a high TOC reduction also occurred through the filters. The indirect methods of measuring biofilm, namely headloss and bed expansion, also yielded measurable results. The filter media with biofilm as sampled from the treatment plants had a higher headloss and bed expansion than the same sample after drying and sieving, which resembles virgin filter media. The sphericity values for headloss decrease by as much as 26% which translates to a headloss gradient increase of 150mm/m at typical filtration rates. The sphericity values for bed expansion decrease by as much as 18% which translates to a bed expansion increase of 17% at normal backwash rates. The conditions at the treatment plants sampled suggest that biofilm growth is stimulated by eutrophic raw water and the presence of pre-ozonation and inhibited when the high pH lime process is used. The mechanism which causes the increased headloss and bed expansion with increased biofilm is hypothesised to be media grains sticking together causing clumping, and not grains which are individually and uniformly covered with a smooth, uniform layer of biofilm. Designers can compensate for this increase in headloss and bed expansion in two ways. They could either apply a correction factor after application of the models to allow for more headloss or bed expansion during eventual plant operation, or they could adjust parameters within the models to account for the larger headloss or bed expansion. As the surface area sphericity was used as a calibration factor in this study and could account for different sets of complex unknowns, it is suggested that this factor is used for adjustment of the model. Operational practice in South Africa often includes in-situ chlorine or acid treatment to alleviate the problem of dirty filter beds. In this study, however, where high and efficient backwash rates were used during tests, no significant improvements in media cleanliness could be attributed to the use of either chlorine or acid. It seems that a good backwash system doesn¡¦t need such remediation, but plants with a backwash system which underperforms might find such remediation useful. / Prof. J. Haarhoff

>Magister Scientiae - MSc / In the Otjozondjupa Region, Namibia, water is transferred from Swakoppoort and Omatako Dams into Von Bach Dam to limit evaporation losses and bring water closer to the purification plant. There is a gap in the knowledge about the effects on water quality in Von Bach Dam due to water transfer from Swakoppoort and Omatako Dams, as previous studies on such aspects in the area do not exist. The study objective was to; (a) characterise water quality of the three dams, (b) determine whether water transfers affect the water quality of Von Bach Dam, (c) determine if the treatment of water abstracted from Von Bach Dam for potable water supply has been influenced by water quality changes arising from water transfers. Four sampling locations were established in Von Bach Dam, one in Swakoppoort Dam, and one in Omatako Dam. Water samples were collected in these three dams weekly. Two senior officers responsible for water treatment were interviewed about possible water treatment problems arising from the water transfer. Descriptive statistics, ANOVA and correlation were carried out to analyse the data. The results showed that, secchi disk depths, total phosphorus, orthophosphate, ammonia, dissolved organic carbon, chlorophyll a and microcystis were statistically different in the three dams at a 5% significance level. Upstream land uses, geology of the catchment and water stratification are likely to influence the water quality in the three dams. During water transfers into Von Bach Dam, secchi disk depths, turbidity, dissolved oxygen, iron, total phosphorus, ammonia (NH₄-N) and chlorophyll a were statistically different at a 5% significance level at all the four sampling locations within this dam. These differences are due to the influence of water transfers. The influence of water transfers on water quality was localised at the discharge points SL4 (at the inflow of Von Bach Dam) and SL1 (at the outflow of Von Bach Dam). Water treatment problems due to high ammonia, dissolved organic carbon, and turbidity in the water abstracted from Von Bach Dam occurred during water transfers and runoff from the catchment. This view was supported by the study findings.

To minimize membrane fouling many water treatment plants pre-treat water prior to microfiltration (MF) or ultrafiltration (UF). Coagulation/flocculation/sedimentation is a common form of pre-treatment, but little research has been conducted on floatation as a part of the pre-treatment. The objective of this thesis is to compare pre-treatment with floatation and with sedimentation for Ottawa River water, a typical Northern Canadian water with a high natural organic matter (NOM) content and a large hydrophobic (HPO) NOM fraction. Fouling tests consisted of multiple filtration/backwashing cycles performed by an automated bench-scale UF hollow fiber membrane system. Test were conducted with Ottawa River water (ORW) and ORW subjected to three different types of pre-treatment conducted at closely-located full-scale water treatment plants, including one using floatation. Both Alum pre-treatments resulted in decreases in NOM (63% and 68% TOC) and HPO NOM (56% and 68%TOC) which helped to reduce fouling. However, the remaining NOM and HPO NOM still caused significant hydraulically and chemical irreversible fouling. The water pre-treated with floatation produced the least severe hydraulically irreversible fouling for all experiments while Raw ORW produced the highest. During the early stages of membrane filtration (~10 hours), the TMP sharply increases which may imply that adsorption is dominant. Statistical analysis during the initial stages of filtration showed that the HPO fraction of NOM was linked to hydraulically irreversible fouling, which may be attributed to adsorption. Raw ORW also had the highest hydraulically reversible fouling while all pre-treatments were able to reduce this type of fouling. Statistical analysis suggested that the transphilic (TPI) fraction of NOM and particulate organic carbon (POC) were responsible for hydraulically reversible fouling during subcritical flux experiments, which may be attributed to cake formation on the membrane surface. It was found that for all waters and experiments, hydraulically irreversible fouling was greater than hydraulically reversible fouling. This may be because of the high HPO concentrations in the ORW. Hydraulically reversible fouling and backwash efficiencies were found to fluctuate with time. It is hypothesised that the cake formation adheres to the membrane surface and is not fully removed until enough backwash pressure has developed. Further investigation into alternative cleaning procedures is required as the NaOH cleaning was not very effective for some of the pre-treated waters.

Dissolved organic nitrogen (DON) represents a significant portion (25-80%) of total dissolved nitrogen in the final effluent of wastewater treatment plants (WWTPs). DON in treated wastewater, once degraded, causes oxygen depletion and/or eutrophication in receiving waters and should be reduced prior to discharge. Biodegradability, bioavailability, and photodegradability are important characteristics of wastewater derived DON and are subjects of research in this dissertation. Four research tasks were performed. In the first task, laboratory-scale chemostat experiments were conducted to examine whether solids retention time (SRT) could be used to control DON and biodegradable DON (BDON) in treated wastewater. Nine different SRTs from 0.3 to 13 were studied. There was no correlation between effluent DON and SRTs. However, BDONs at SRTs of 0.3 to 4 days were comparable and had a decreasing trend with SRTs after that. These results indicate the benefit of high SRTs in term of producing effluent with less BDON. The second task was a comprehensive year-round data collection to study the fate of DON and BDON through the treatment train of a trickling filter (TF) WWTP. The plant removed substantial amounts of DON (62%) and BDON (76%) mainly through the biological process. However, the discharged concentrations in the effluent were still high enough to be critical for a stringent total nitrogen discharge limit (below 5 mg-N/L). Evolution of bioavailable DON (ABDON) along the treatment trains of activated sludge (AS) and TF WWTPs and relationship between ABDON and BDON were examined in the third task. ABDON exerted from a combination of bacteria and algae inocula was higher than algae inoculated ABDON and bacteria inoculated BDON suggesting the use of algae as a treatment organism along with bacteria to minimize effluent DON. The TF and AS WWTPs removed 88% and 64% of ABDON, respectively. In the last task, photodegradable DON (PDON) in primary wastewater and final effluent from TF and AS WWTPs was studied. PDON and BDON fractions of DON data in the final effluent of TF and AS WWTP samples elucidate that photodegradation is as critically important as biodegradation when mineralization of effluent DON is a concern in receiving waters.

Kläder och textilier produceras och konsumeras i allt högre grad med stor påverkan på miljö, klimat och jordens resurser som följd. En attraktiv lösning på det är återvinning av kläder, vilket företaget re:newcell gör. Detta är en förstudie med syfte att undersöka vilka reningsmetoder re:newcell skulle kunna implementera för att förbättra sin vattenreningsprocess i framtiden. Tre ämnen vars halter i nuläget inte reduceras i reningen valdes ut till studien: nonylfenol, bromerade flamskyddsmedel och sulfat. En litteraturstudie kring dessa ämnen och möjliga reningsmetoder resulterade i att tre lämpliga reningsmetoder valdes ut till studien: ozonering, biologisk rening och jonbyte. En försöksplan utformades med målen att ta reda på (1) hur tidigare rapporterade ozondoser påverkade nonylfenolhalten i re:newcells vatten, (2) hur stor andel TOC (Total Organic Carbon) en MBBR (moving body bioreactor) kunde reducera och (3) ifall PBDE (bromerade flamskyddsmedel) och sulfat var möjliga att bryta ner med i en MBBR, (4) hur stort jonbytarfilter som skulle krävas i re:newcells process för att reducera sulfathalten samt (5) i vilken ordning reningsstegen bör implementeras i framtida reningsprocesser. Ozoneringsförsök utfördes på re:newcells laboratorium i Kristinehamn med totalt fem olika ozondoser. En biologisk MBBR utformades i laboratorium på Karlstad Universitet, där två olika uppehållstider testades för reducering av flamskyddsmedel, sulfat och TOC. Beräkningar på jonbytarfilter utfördes teoretiskt. En ozondos på 0,45 mgO3/mgCOD gav en reducering på ca 31 % och 0,75 mgO3/mgCOD gav 78 % reducering vid en nonylfenolhalt på 1100 mg/L. Resultaten från MBBR visar att bakterier trivs i re:newcells vatten och att de kunde reducera TOC med ca 50 %. Däremot kunde ingen reducering av sulfat uppmätas, vilket tyder på att ingen anaerob zon har uppstått. Halten av PBDE reducerades med ca 90 % med en uppehållstid på 45 h i MBBR, men om det beror på nedbrytning eller adsorption till slammet är inte fastställt. Resultaten från beräkningen på jonbytarfiltret visade att filtret behöver vara 5,7-15 m3 vid regenerering en gång per dygn i re:newcells nuvarande pilotskaliga process. Denna metod anses därmed inte vara en lämplig för sulfatreducering. Den framtida reningsprocessen föreslås starta med MBBR och efterföljande sedimentering, följt av kemfällning, sedimentering/flotation, sandfilter, ozonering och sist aktivkolfilter, men vidare studier rekommenderas rörande vilken ordning reningsstegen bör implementeras för optimal effekt. Vidare studier kring vilken ozondos som krävs och vilken uppehållstid som är optimal i MBBR föreslås också. / Clothes and textiles are increasingly produced and consumed causing a major impact on the environment, the climate and the earth's resources. One solution to the problem is to recycle clothes that are no longer used, which is what the company re:newcell does. This is a feasibility study aimed at investigating what purification methods re:newcell could implement to improve their water purification process in the future. Three substances not currently purified sufficiently were selected for the study: nonylphenol, brominated flame retardants and sulfate. A literature review on these substances and possible purification methods for them resulted in that the following methods were selected for the study: ozonation, biological purification and ion exchange. An experimental plan was developed with the aim of finding out (1) how previously reported ozone doses affected the nonylphenol content in re:newcell's water, (2) how much TOC an MBBR (moving body bioreactor) could reduce, (3) and whether the levels of brominated flame retardants and sulphate were possible to reduce in it,  (4) the required size of the ion exchange filter in re:newcells process to reduce sulfateand (5) the order in which the purification steps should be implemented in future purification processes. Ozonation experiments were carried out at re:newcell's laboratory in Kristinehamn with a total of five different ozone doses tested. A biological MBBR was designed in a laboratory at Karlstad University, where two different hydraulic retention times were tested for reducing flame retardants, sulfate and TOC. Calculations on ion exchange filters were performed theoretically. An ozone dose of 0.45 mgO3/mgCOD produced a reduction of about 31% and 0.75 mgO3/mgCOD produced a 78% reduction at a nonylphenol content of 1100 µg / L The results from MBBR showed that bacteria thrived in re:newcell´s water and that they can reduce TOC by about 50 %. However, reduction of sulfate could be measured, suggesting that no anaerobic zone has occured. The content of PBDE was reduced by about 90% with a hydraulic retention time of 45 hours in MBBR, but whether it is due to degradation or adsorbation to the sludge is not determined. The calculation regarding the ion exchange filter show that the filter needs to be 5,7-15 m3 when regenerated once a day in re:newcell's current pilot scale process this method is therefore not considered appropriate  for sulfate reduction for re:newcell. The future purification process is proposed to start with MBBR and subsequent sedimentation, followed by chemical precipitation, sedimentation / flotation, sand filter, ozonation and last activated carbon filter, but further studies are recommended regarding which order the purification steps should be implemented for optimal effect. Further studies on which ozone dose is required and which residence time is optimal in MBBR are also suggested.