M.Sc. (Chemistry) / Volatile fatty acids (VFAs) play a pivotal in the process of nutrient removal by biological processes particularly the enhanced biological nutrient removal process with a side-stream elutriation process using activated sludge. These acids are said to act as intermediates which provide feed for the organisms in a biological phosphorus and nitrogen removal (BNPR) system, such as phosphorus-accumulating organisms (PAOs) and nitrate-accumulating bacteria (NABs). In wastewater treatment plants, VFAs play a vital role as intermediate organic compounds during the fermentation processes which generate methane gas and when present at elevated levels they are known to cause microbial stress, acidification as well as the poor performance of anaerobic digesters. For these reasons, the routine monitoring of VFA levels in wastewater treatment plants is crucial as they will act as indicators of the efficiency and optimal operation performance of the anaerobic digesters. Normally the VFAs that are commonly produced during the anaerobic fermentation process include acetic acid, propionic acid, butyric acid, and valeric acid and of these, acetic and propionic acids form the major VFAs that are generated, thus the yields of these two compounds provide a useful measure of the anaerobic digester performance. For example, the ratio of propionic acid to acetic acid is always used as an indicator of digester imbalance while high concentrations of acetic acid (e.g. > 800 mg/ℓ) or a propionic acid to acetic acid ratio greater than 1.4 is an indication of digester failure. This study was thus aimed at establishing the complete VFA profile at the Johannesburg Water (JW) Northern Works Wastewater Treatment Plant in Johannesburg, South Africa, by developing analytical methods to quantify the VFAs in the wastewater treatment plant. In addition, the level of VFAs quantified was used to evaluate the efficiency of the fermentation treatment process in wastewater treatment systems in order to give an indication of the bacterial activities in the systems; to determine the ratios of the VFAs, especially the propionic acid to acetic acid ratio, to establish the performance and efficiency of various wastewater treatment plants; and to determine whether there is any imbalance in the anaerobic digesters. Two analytical methods for the determination of VFAs were successfully developed and applied to real wastewater samples. The first method developed was a liquid-liquid extraction method using gas chromatography time-of-flight mass spectrometry (GC-TOF-MS. The method involved two extracting solvents, namely dichloromethane (DCM) and methyl-tert-butyl ether (MTBE). The extraction capacity of these two solvents was compared. The second method successfully developed and optimised headspace-solid phase microextraction (HS-SPME) using GC-TOF-MS. The microextraction fibre used was a polydimethylsiloxane (PDMS) fibre. Studies to validate the developed methods were also carried out by calculating the limit of detection (LOD) and limit of quantification (LOQ). Ratios of propionic acid to acetic acids were determined as well as the concentrations of acetic acid for both developed methods in order to evaluate the performance and efficiency of the treatment process. The results of the study show that the extraction procedure using solvents DCM and MTBE showed that exhaustive extraction was achieved by MTBE. Higher concentrations of acetic acid and propionic acid were obtained by MTBE. The overall fermentation performance for all three units in the period when the samples were collected, which was measured by the ratio of propionic to acetic acid was good since the ratio did not exceed 1.4. The acetic acid concentration in mg/ℓ was < 800 mg/ℓ for all units thus it can be said that the reactor balance was maintained for the period studied. The method LOD ranged from 0.034 mg/ℓ to 0.21 mg/ℓ and the method LOQ ranged from 0.11 mg/ℓ to 0.70 mg/ℓ. Optimisation of extraction parameters was achieved for headspace solid-phase microextraction using the PDMS fibre method. The extraction method was conducted for 60 min using a sample volume of 4 mℓ and the amount of sodium salt added was 1.50 g. The desorption temperature and time was 210ºC and 5 min, respectively. The LOD values ranged from 0.079 to 2.07. The PDMS fibre was found to be suitable for extracting higher carbon chain fatty acids as compared to lower carbon chain fatty acids. The plant performance for the period studied was on par as indicated by ratios of propionic acid to acetic acid which all fell below 1.4. There were no digester failures for the period studied. The acetic acid concentration in mg/ℓ was < 800 mg/ℓ for all 3 units.

This study documents that external and internal forces were causes of change at VCWTP. External forces caused. Fort Worth to reorganize and introduce new management at VCWTP after 1982. These improvements led to VCWTP being selected best managed wastewater treatment plant in the nation by EPA in 1988. This study first analyzes external and internal forces responsible for changes at VCWTP. A history of plant operations also is reviewed. Personnel interviews were conducted of perceptions of employees. Finally, statistics obtained of the plant operation from 1969 to 1988 are compared with personal interviews. Five forces effect change at VCWTP; population, regulatory requirements, political conflicts, an organizational and managerial factors. Turnaround occurred as external and internal corrections were made.

The discharge of point- and non-point source pollutants into surface waters resulting from industrial and/or municipal activities is a major focus of environmental regulation in the United States. As a result, the National Pollutant Discharge Elimination System (NPDES) permit program was established in 1972 in an effort to regulate discharges from industrial or municipal sources, including wastewater treatment plants (WWTP). To further protect Florida water quality, in 1978, State legislation enacted the Grizzle-Figg Act for Tampa Bay, which requires advanced wastewater treatment for any discharge into sensitive water bodies. A common use of wastewater effluent in the Tampa Bay area is for reclaimed water for irrigation. This leads to an estimated 90% reduction of total nitrogen (TN) load to the bay in comparison to direct discharge (TBEP, 2016). One type of wastewater treatment process that has been shown to have low aeration and chemical requirements is simultaneous nitrification denitrification (SND), which can be carried out in an oxidation ditch. SND is a biological process for nitrogen removal where nitrification and denitrification occur at the same time within the same reactor. An oxidation ditch is a race-track type reactor that promotes the occurrence biological conversion of reactive nitrogen to nitrogen gas (N2) and additionally can provide enhanced biological phosphorus removal (EBPR). Many theories exist as to the mechanisms that allow SND to occur, but the literature is inconclusive as to whether the presence of different zones within the floc, within the reactor itself, a combination of the two or unique microorganisms are responsible for SND. Advantages of SND include efficient (80-96%) nitrogen removal, with significant reductions in energy, chemical, equipment and spatial requirements. Specifically, oxygen requirements are reduced and dedicated aerobic/anoxic zones, internal recirculation and supplemental carbon and alkalinity are not required. Despite these advantages, widespread use of SND is limited because of a lack of understanding of SND kinetics as well as interactions between factors affecting SND performance. This research was carried out at the Falkenburg Advanced Wastewater Treatment Plant (AWWTP) in Hillsborough County Florida, which carries out SND, biological and chemical phosphorous removal in an oxidation ditch system. Although this facility continually meets and exceeds its permit requirements, improvements in process control strategies have the potential to improve energy efficiency, as well as decrease chemical use, sludge production, greenhouse gasses (GHG) emissions and costs. Therefore, the overall goal of this research was to investigate mechanisms of nitrogen and phosphorus removal at the Falkenburg AWWTP. These goals were achieved through bench scale SND studies carried out at varying temperatures. Kinetic parameters were determined using a simple kinetic model of nitrification/denitrification. Additionally, carrying out sampling campaigns completed the investigation of the fate of phosphorus in the Falkenburg AWWTP. The results were combined with information on alum dosing and sludge wasting to determine the overall fate of phosphorus in the system and make additional recommendations regarding the addition of alum. To mimic an oxidation ditch at Falkenburg AWWTP, bench scale bioreactor experiments were set up in glass beakers at 22°C and 29.5 C. Influent wastewater and return activated sludge (RAS) for these experiments were collected from the Falkenburg AWWTP. Bioreactors were constantly mixed and aeration was controlled to maintain a target dissolved oxygen (DO) concentration based on measurements of DO at the facility. Three phosphorous sampling campaigns (October, November and December) were also carried out to understand the fate of phosphorous, nitrogen and organic carbon at the facility. In these campaigns, samples were taken at six locations at Falkenburg AWWTP and samples were analyzed for filtered and unfiltered total phosphorus, orthophosphate and polyphosphates, filtered and unfiltered total nitrogen, soluble, total and readily biodegradable COD (rbCOD), volatile acids, cations, anions, alkalinity, total suspended solids (TSS) and volatile suspended solids (VSS). pH and DO were also measured on site. In the nitrification batch reactors, in four hours, 50% of ammonia was successfully removed at a rate of 6.31 mg-N/L/hr indicating that four hours is not sufficient time to achieve complete removal. In the denitrification batch reactors, in six hours, there was successful removal of nitrate and nitrite at a rate of 23.70 mg-NO3-/L/hr and 3.6 mg-NO2-/L/hr. In an SND batch reactor experiments at 22° C, ammonia oxidation successfully occurred in 12 hours but denitrification was inhibited due to insufficient rbCOD in the reactor. In an SND batch reactor at 29.5° C, no accumulation of nitrate or nitrite was observed, indicating successful SND. At a higher temperature, sludge bulking occurred in the reactor resulting in variations in TSS and VSS concentrations. Results from the sampling campaigns at the treatment plant indicate that successful phosphorus removal was achieved. Alum addition varied before each sampling and a relationship between alum addition and sulfate can be made. rbCOD was consumed throughout the treatment process as expected and noticeable results can be noted when rbCOD was low in terms of phosphorus removal. The results of the bench-scale experiments showed that the SND was successfully achieved at the Falkenburg facility and that temperature, DO and rbCOD are all important factors controlling biological nutrient removal at SND facilities. DO is much more difficult to maintain and control at a higher temperature further supporting the idea that stricter operator control is needed in warmer months. Additionally, because SND removal still occurred with poor DO control at 29.5°C, it further supports the idea that SND occurs because of zones within the floc, the reactor or that novel microorganisms exist that allow denitrification to occur above ideal DO concentration and nitrification to occur below ideal concentrations of DO. A variation in rbCOD in the influent wastewater at the treatment plant caused nitrification and denitrification to be inhibited in different trials. With too much rbCOD, nitrification was inhibited and with too little rbCOD, denitrification was inhibited. Additionally, alkalinity consumption was minimal which supports the idea that supplemental alkalinity is not needed in SND processes. The results from the phosphorous sampling campaign show how important influent COD is for successful phosphorus removal in the system. The objectives were achieved and overall, the plant is achieving SND and EBPR and the plant is performing as designed. The addition of alum should continue to be studied to determine a better dose and save the county ratepayers money while still meeting permit regulations. Jar tests should be used to determine the proper dosing that will not hinder the settling properties further in the treatment train. Additionally, alum feed pipe sizes should be investigated at the plant to ensure no clogging occurs with a decrease in alum flow and automated aeration based on ammonia concentrations should be considered to remove the manual operation of aerators.

Zeolites were used in this study to remove two types of non-radioactive ions (Cobalt-59 and Strontium-89) from wastewater. This was designed to model the use of ion-exchange technique to remove radioactive Co-60 and Sr-90 from low level wastewater from Al-Tuwaitha site. Al-Tuwaitha site is a nuclear research in Iraq was used for radio-medical and radio-chemical purposes before 1990. In this study, hierarchical microporous/macroporous structures were developed to overcome the diffusivity problem using zeolite. Diatomite and carbon were used to prepare the composite adsorbents by incorporating them with three types of zeolites (A, Y and clinoptilolite). From the XRD, SEM and EDAX measurement it was confirmed that successfully prepared of Iraqi palm tree leafs-Clinoptlolite (IPClinp) and Tamarind stones-Clinoptilolite (TSClinp) composites were obtained in this study as there is no evidence in literature of this being carried out before. The carbons were prepared successfully through the Pyrolysis method for 2h at 900°C in an inert atmosphere from two types of raw waste plant materials of Iraqi Palm Tree leafs (IP) and Tamarind stones (TS). For both types of carbons, the SEM images show organised porosities in different shapes. A third material used as a zeolite scaffold was diatomite (Celatom FW-14) a readily available natural material (dead algae).A hydrothermal treatment was used to build the hierarchical structure of zeolite onto carbon and diatomite materials, the scaffolds were seeded with nano-zeolite crystals prior to the treatment and thereafter mixed with the zeolite gel composition mixture in a stainless steel autoclave. Zeolite seeds were prepared using ball mill method to reduce the particle size of the commercial zeolite to sub-micron range for each type of zeolite. The surface area, morphology, element compositions and structure for each type of zeolite and composite material were characterised using BET method, SEM, EDAX and XRD. The amounts of each type of zeolite on the carbon composites were determined using TGA while that of the diatomite composite was determined by gravimetric analysis. The results show that each type of zeolite was successfully deposited and uniformly organised onto the surface of all support materials. All pure zeolites and composite materials were successfully tested to remove Co2+ and Sr2+ ions from aqueous solutions. It was found that the composite materials had higher ability to remove both ions relative to the pure zeolites. This increase is attributed to the deposition of zeolite (microporous) onto the macroporous structure (carbon and diatomite) which increased the flow accessibility within zeolite in the hierarchical structured composites. Comparison of the removal between the two metal ions indicates that all of the materials had higher uptake for Sr2+ than Co2+ ions. The highest adsorption capacities were realised with Tamarind Stone–ZeoliteA (TSA) in the order 120mg.gz-1and 290mg.gz-1 for Co2+ and Sr2+ ions, respectively. The effect of the experimental variables shows increasing uptake with increasing pH and initial ion concentrations while it decreased with increasing the solution temperature. The Co2+ loaded composites was subjected to vitrification process at 12000C for 2h. The encapsulated composites were leached for 90 and 120 days and no significant Co2+ was recorded in the leached solution. The results show that the composite materials can be used effectively to remove the radioactive ion of Co-60 and Sr-90 ion as they display the same chemical behaviour as Co-59 and Sr-89 studied in this work.

Visible light-driven photocatalysis has shown considerable potential in the area of clean and renewable energy, as well as in wastewater treatment. This thesis describes the synthesis, characterization and applicability of a visible-light active photocatalyst, bismuth oxybromide (BiOBr). The photocatalytic activity of BiOBr was investigated through its preparation via hydrothermal and solvothermal synthesis routes under various conditions. Hydrothermal catalyst was prepared using non template based method while for solvothermal synthesis CTAB was used as a template. Parameters of temperature and time of thermal treatment were optimized for each synthesis method and overall tests for catalyst dosage and recyclability were performed. An overall optimal route leading to high photocatalytic performance was also proposed based on the obtained results. Studies were also conducted to examine the applicability of optimally synthesized BiOBr in drinking water applications by studying catalyst-mediated disinfection of E. coli and degradation of phenol. Favourable results were obtained, confirming the prospective application of BiOBr as a viable photocatalyst for disinfection. Furthermore, the potential of enhancing BiOBr to further improve its performance is described through synthesis of a novel PdCl2/BiOBr based photocatalyst. Overall, the performance of BiOBr under various conditions in this study establishes its potential as a holistic photocatalyst and merits further development.

Le but ultime de cette recherche était d'élaborer un cadre qui intègre les efforts expérimentaux et de calcul pour évaluer l'exposition des IP en métal et métal - oxyde libérés de stations d'épuration et d'autres implications sur Laus où les biosolides peuvent être appliquées. La fondation de l'effort de calcul est composée de modèles de bilan de masse de Monte Carlo qui représentent les processus uniques qui affectent NP sort et le transport à travers les différents compartiments techniques d'une station d'épuration et LAU. Analyse fonctionnelle et des expériences de bioréacteurs dans les milieux naturels ont été utilisés pour déterminer les paramètres permettant de décrire les processus critiques qui ont un impact sur ​​le sort des infirmières praticiennes dans les eaux usées. Les résultats de cette recherche indiquent que simplifiée, mais l'évaluation de l'exposition toujours d'actualité de l'environnement spécifique nano est possible grâce à l'expérimentation de paramétrer des modèles adaptés. Boîte noire efforts de modélisation, qui ont été indiquées dans les études précédentes, ne montrent pas de désavantage par rapport à la discrétisation des compartiments techniques aussi longtemps que tous les mécanismes de transport et de devenir les principaux sont pris en compte. Le coefficient de distribution (γ), peut être utilisée pour prédire la distribution des NPs. Pour les NPs de métal et d'oxyde métallique étudiés, association globale préférentiel d'environ 90% ou plus avec la phase solide des eaux usées a été observé et prédit. En outre, les réactions d'oxydo-réduction auront une incidence sur l'exposition et doivent être pris en compte. / The ultimate goal of this research was to develop a framework that incorporates experimental and computational efforts to assess and better understand the exposure of metal and metal-oxide NPs released to WWTPs and further implications on LAUs where biosolids can be applied. The foundation of the computational effort is comprised of Monte Carlo mass balance models that account for the unique processes affecting NP fate and transport through the different technical compartments of a WWTP and LAU. Functional assay and bioreactor experiments in environmental media were used to determine parameters capable of describing the critical processes that impact the fate of NPs in wastewater. The results of this research indicate that a simplified, but still environmentally relevant nano-specific exposure assessment is possible through experimentation to parameterize adapted models. Black box modeling efforts, which have been shown in previous studies, show no disadvantage relative to discretization of technical compartments as long as all key transport and fate mechanisms are considered. The distribution coefficient (γ), an experimentally determined, time-dependent parameter, can be used to predict the distribution of NPs between the liquid and solid phase in WWTPs. For the metal and metal-oxide NPs studied, preferential overall association of approximately 90% or greater with the solid phase of wastewater was observed and predicted. Furthermore, NP transformations including dissolution, redox reactions, and adsorption will impact exposure and must be accounted for.

Due to their potential health impact on human beings and ecosystems, persistent trace organic compounds (TOrCs) have aroused concern from both the public and professionals. In particular, the discharge of pharmaceuticals, endocrine disrupters, disinfection byproducts and other TOrCs from wastewater treatment plants into the environment is an area of extensive current research. This work studies the fate and treatments of TOrCs, with emphases on advanced oxidation processes (AOPs). This work presents predicted removal efficiencies of a variety of engineered and natural processes for 55 frequently encountered TOrCs in treated wastewater, based on previously reported data and using existing predictive models. Correlations between physicochemical and biological properties of TOrCs and treatment performance were explored. Removal of TOrCs in all processes investigated in this study was found to be sensitive to matrix effects. Heuristic guidelines for selection of sequenced treatment processes for TOrCs management were established. A field reconnaissance of natural process of TOrCs was conducted by analyzing the occurrence and fate of a suite of TOrCs, as well as estrogenic activity in water and sediments in the Santa Cruz River, an effluent-dependent stream in Tucson, Arizona. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. TOrCs that have low biodegradability and low octanolwater partitioning coefficients were less removed. Results of independent experiments indicated potential indirect photodegradation of estrogenic compound by reactive species generated from photolysis of effluent organic matter. Utilizing advanced oxidation processes (AOPs) as tertiary water and wastewater treatment is an option to prevent discharge of TOrCs into the environment. Compared to conventional AOPs, the ability of generating hydroxyl radicals (•OH) without additional doses of hydrogen peroxide (H2O2) or ozone makes ultraviolet (UV) photolysis of ferric hydroxo complexes a novel AOP, especially in acidic environments. A Fe(III)/UV254 kinetic model, which combines Fenton-like mechanism, and photolyses of Fe3+, FeOH2+ and H2O2 was proposed and experimentally validated to predict Fenton-like and H2O2 direct UV254 photolysis scenarios, individually. Nevertheless, the model underestimated the ferrous ion development during Fe(III)/UV254 photolysis, perhaps due to the overprediction of the oxidation of Fe2+ by •OH. The UV/H2O2 AOP was also studied in this work. A predictive kinetic model was developed to evaluate process efficiency of oxidation of p-cresol by UV/H2O2 photolysis based on a complete reaction mechanism, including reactions of intermediates with •OH. Results of this study highlight the significance of consideration of radical scavenging effects by the byproducts from oxidation of organic matter in model prediction performance.

Les objectifs de ce travail étaient de déterminer les sources et le devenir de l’arsenic dans une papeterie vosgienne, et en particulier dans sa station d’épuration, afin de comprendre les variations de la concentration en arsenic dans l’effluent traité par la station et rejeté dans la Moselle.Les papiers récupérés utilisés pour la production de pâte désencrée représentent la source majoritaire d’arsenic pour la papeterie, puis les combustibles incinérés dans le secteur énergie. Les sorties majoritaires sont les cendres produites par le secteur énergie, puis le papier produit. Le devenir de l’arsenic dans le procédé de désencrage est complexe et implique des phénomènes de transfert entre le circuit de la pâte à papier et le circuit des eaux. L’arsenic présent dans les eaux blanches semble provenir des matières en suspension. Des dysfonctionnements dans le secteur énergie ont causé le départ de cendres produites dans la chaudière à la station d’épuration via les eaux de lavage du laveur de fumées. Ces cendres peuvent avoir une concentration en arsenic très importante et pourraient être l’une des causes des dépassements de la limite de rejet en arsenic. La station d’épuration peut éliminer de la phase aqueuse jusqu’à 50 % de l’arsenic entrant à la station après neutralisation/décantation et traitement par boues activées. Un traitement tertiaire par coagulation (par des sels d’aluminium) / floculation / flottation permet de diminuer encore la concentration en arsenic dans le rejet en fonction des conditions de fonctionnement / This study was about the sources and the fate of arsenic in a pulp and paper mill located in the Vosges, and particularly in the wastewater treatment plant, in order to understand the variations of the arsenic concentration in the treated effluent discharged in the Moselle River.The recovered papers used for the production of deinked pulp are the main source of arsenic for the pulp and paper mill, followed by the solid fuels incinerated in the boiler of the energy area of the mill. The main outputs are the ashes produced by the boiler, then the produced paper. The fate of the arsenic in the deinking process is complex and involves transfer phenomena between the pulp and the white water of the process. Arsenic present in white water could come from the suspended solids. Malfunctions in the energy area have caused the departure of ashes to the wastewater treatment plant via the washing water of the flue gas washer. Those ashes may contain a high arsenic concentration and could be one of the sources of the large variations of the arsenic concentration in the effluent of the wastewater treatment plant. This wastewater treatment plant is able to eliminate up to 50% of arsenic of the effluent thanks to neutralization/decantation and biotreatment by activated sludge. A tertiary treatment by coagulation (with aluminum salts) / flocculation / flotation permits to decrease the arsenic concentration in the effluent according to the operating conditions

The diploma´s thesis deals with possibilities and limits of export of Czech goods with a specific focus on facilities for wastewater treatment plants in the Russian Federation. In compliance with the theory of internationalization, the first chapter introduces individual forms of entry to foreign markets. Choosing some of the entry modes including export, the thesis mentions specifics of their application on the Russian market. The following chapter outlines current Czech-Russian trade relations which result from valid bilateral, regional and multilateral agreements so as from the crucial political-economic events. In the case study the thesis deals with the very specific opportunities and barriers for the export of Czech facilities for wastewater treatment plants. Therefore, in the particular subchapters the thesis analyzes the current condition of wastewater treatment management in Russia and the legislative and program documents, which stimulate the development and modernization of existing infrastructure. Moreover, the thesis discusses factors that make it difficult to enter the Russian market by Czech companies. Since one of the problems is project financing in Russia, the last chapter deals with the possibilities of financing and insuring export with state support. Overall, the thesis aims to cover the stimuli for export of given goods to Russia, the problems which the exporters might face and their possible solutions as well.

A carepa é um resíduo da produção de aço gerado principalmente nas etapas de lingotamento e laminação. O objetivo do presente trabalho foi a produção do coagulante cloreto férrico a partir da carepa oriunda da indústria siderúrgica. Em termos experimentais, foram realizados ensaios de solubilização da carepa avaliando-se o efeito da concentração de ácido clorídrico, tempo de reação e temperatura. Ainda, avaliou-se a oxidação do Fe2+, presente no liquor, para Fe3+ por dois métodos distintos, sendo adição de peróxido de hidrogênio e injeção de ozônio. A solução de cloreto férrico produzido a partir da carepa foi caracterizada e aplicada no tratamento de esgoto doméstico sanitário de uma instituição universitária. Como resultado, a melhor condição para a dissolução da carepa foi com o uso de uma solução de HCl 90%, tempo de reação de 2 horas a uma temperatura de 80oC. Nesta condição, a eficiência de dissolução da carepa foi de 90%. A completa oxidação do Fe2+ dissolvido no liquor para Fe3+ foi possível tanto com a adição de H2O2 como com O3. Contudo, o processo de ozonização apresenta vantagens, pois estequiometricamente é mais eficiente e não dilui a solução rica em cloreto férrico. A análise físico-química do coagulante produzido com a digestão da carepa com HCl 90% e oxidada com ozônio, após evaporação, atendeu ao critério de concentração de Fe de no mínimo 12% em volume. A aplicação do reagente no tratamento de um esgoto doméstico sanitário mostrou que é eficiente na remoção de sólidos suspensos e fósforo. Por fim o estudo mostrou que é possível produzir um coagulante a partir da carepa gerada na indústria siderúrgica. A prática sugerida neste trabalho pode reduzir a quantidade de resíduos deslocados para aterros industriais pela indústria siderúrgica. / Mill scale is a residue of steel production generated mainly in casting and lamination phases. The objective of this work was the production of the ferric chloride coagulant from the mill scale which comes from the steel industry. In experimental terms, trials of mill scale solubility were carried out in order to evaluate the effect of hydrochloric acid concentration, reaction time and temperature. After that, the oxidation of Fe2 +, present in the liquor, to Fe3 + was evaluated by two distinct methods, addition of hydrogen peroxide and ozone injection. The ferric chloride solution produced from mill scale was characterized and applied in the sewage treatment of a university campus. As a result, a good condition for the dissolution of mill scale was with the use of 90% HCl solution, reaction time of 2 hours, at a temperature of 80ºC. In this condition, the efficiency of mill scale dissolution was of 90%. The complete oxidation of Fe2+ dissolved in the liquor for Fe3+ was possible both with the addition of H2O2 as well as with O3. However, the ozonation process has advantages because it is stoichiometrically more efficient and does not dilute the solution rich in ferric chloride. Physico-chemical analysis of the coagulant produced with the dissolution of mill scale with 90% HCl and oxidized with ozone, after evaporation, answered to the criterion of Fe concentration of, at least, 12% in volume. The use of the reagent in the treatment of a sewer showed that it is effective in removing suspended solids and phosphorus. Finally, it is possible to produce a coagulant from mill scale produced in the steel industry. The practice suggested in this work can reduce the amount of waste sent to industrial landfills by the steel industry.