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Dewatered sludges and biosolids generated from wastewater treatment facilities are known to emit malodorous odors causing public inconvenience. The odors typically comprise of reduced organo sulfur based compounds and nitrogen containing compounds. Lime stabilization is a technique which is commonly used in the wastewater industry to produce biosolids having reduced odors that can be safely land disposed. In this research, odors produced from dewatered sludges and lime stabilized biosolids were investigated. Lime dosing and incorporation in sludge play an important role in generation of reduced sulfur and trimethylamine (TMA) odor compounds. Results revealed that poor lime dosing can lead to an increase in odors due to biological generation of volatile sulfur compounds (VSCs) during storage. In this study, a belt filter press gave a higher production of sulfur and TMA odors compared to a vacuum filter for the same sludge, which is attributed to the shear imparted to sludge during the dewatering process. Preliming studies suggested incomplete mixing of lime with sludge led to biological activity. The achievement of the correct pH and its maintenance during storage is considered critical for effective odor management from lime stabilized biosolids. A positive linear relation was obtained between sulfur based odor production and labile protein content in sludge. Furthermore, as the Al/Fe ratio increased, the labile proteins was observed to decrease. Trivalent metals are found to play an important role in binding of labile proteins thus effecting odor potential contained in sludge/biosolids. This was found true for most sludge irrespective of their liming status and independent of upstream process conditions. Further work in this area is needed to be able to provide a better understanding of odor production to aid in development of odor control techniques. Trimethylamine odors, having a characteristic fishy odor, are commonly found in lime stabilized biosolids. Cationic polymers used as dewatering aids are the primary precursors for TMA production. Proteins present in sludge are also associated with odor forming compounds but they produce much lower levels than polymers. These two components under the action of shear present in dewatering devices such as centrifuge are more likely to cause an increase in odor production from lime stabilized biosolids. It was also determined that abiotic polymer degradation to produce TMA either does not occur, or the rate is so slow that TMA production in this way is insignificant for actual field situations. / Master of Science

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The Swedish Environmental Agency (SEPA) proposed a national target to increase the rate of phosphorus recycling from wastewater sludge in 2013. Reusing phosphorus from wastewater sludge by spreading it on arable lands raises the risk of contamination and substance deposition in soils. In addition to quantifying the targeted rate of recycling, the proposal has also introduced new thresholds that limit the concentrations of undesired substances in wastewater sludge. This thesis assesses the potential challenges and opportunities in implementing the proposed measure in the Swedish municipality settings. Both qualitative and quantitative data have been gathered from three selected mid-sized Swedish municipalities in the Östergötland County and other data sources. The analytical framework of the thesis is based on the Systems Framework for Phosphorus Recovery and Reuse. Several discrepancies between the national goal to increase phosphorus recycling and local circumstances that affect local decision-making have been identified in this thesis. Reducing the flow of undesired substances into the wastewater stream raises goal conflict and is an enormous challenge which requires regulating the way chemicals are consumed in society. From the policy perspective, the national environmental objectives framework is ambiguous with regards to how local decisions should be directed in line with the national goals. The proposed measure should hierarchically be unequivocal and its implementation needs to be coordinated across all geographical scales. The thesis also highlights that there are significant local opportunities for addressing other sustainability goals through phosphorus recycling measures. Sweden’s commitment to creating a resource-efficient phosphorus cycle affirms that the key for a sustainable phosphorus management is the transformation of path-dependent social and technical systems.

A growing population, urbanization and an increase in the number of industries is causing an increase in sewage sludge (SS) that needs to be either beneficially used or disposed of. Application of SS to agricultural lands is a well-known practice but the plant available phosphate and phosphate fertilizer value of SS has been of concern. This is especially due to the wide variety of soils that SS is applied to and the different phosphate removal processes that sewage waste water undergoes at the water care works and the source used to produce SS. Phosphate phyto-availability and phosphate fertilizer value of petrochemical and municipal wastewater sludges (SS) were determined in four different soils using an incubation study over 168 days, a pot trial over 42 days and a field trial over one season. Phosphate phyto-availability was determined/calculated by means of an incubation approach. Soils were incubated with sludge as well as mono ammonium phosphate (MAP). The soils were then subjected to a Bray-1 extraction after a certain time (42 days, 168 days). The relative phosphate fertilizer value (RPFV) was then expressed as a percentage of the Bray-1 extractability of the sludge-amended soil, relative to the MAP-amended soil. The influence of soil properties, especially clay content, and sludge properties namely phosphate extraction method (chemical and biological) from waste water stream, was investigated to determine the effect on phytoavailability and fertilizer value of phosphate in SS-amended soil. Soil properties were the dominant factor determining plant available phosphate, where plant available phosphate decreased with increasing clay content, irrelevant of the type of treatment. There were, however, significant differences between the chemical and biologically removed SS, where the biologically removed SS had higher plant available phosphate. The RPFV % of the SS was comparable to MAP in terms of its plant availability. Wetting and drying cycles in the pot trial influenced the plant available phosphate from the SS, where the chemically treated sludge showed in general lower plant availability. The RPFV % of the biologically removed phosphate sludges was better than that of MAP and that of the chemically phosphate removed sludge were lower. Application of all the different sludge types resulted in a positive reaction on plant available phosphate for all the soils. All the trials were conducted at pH of about 5.5. However, it is expected that biologically P removed sludge will perform better in acid soils. The reason being that ferric phosphate in the chemically treated sludge is less soluble under pH conditions lower than 5.5 than above it. / Dissertation (MScAgric)--University of Pretoria, 2014. / tm2015 / Plant Production and Soil Science / MScAgric / Unrestricted

Olive mill wastewater sludge (OMWS) is the solid residue that remains in the evaporation ponds after evaporation of the majority of water in the olive mill wastewater (OMW). OMWS is a major environmental pollutant in the olive oil producing regions. Approximately 41.16 wt. % of the OMWS was soluble in hexanes (HSF). The fatty acids in this fraction consist mainly of oleic and palmitic acid. Catalytic pyrolysis of the OMWS over red mud and HZSM-5 has been demonstrated to be an effective technology for converting this waste material into fuel. Red mud-catalyzed pyrolysis gave higher organics yields than the HZSM-5 catalysis. The viscosity as well as the oxygen content of the catalytic pyrolysis oils were significantly lower than those of the non-catalytic oil. The reaction pathways of red mud and HZSM-5 were different. The catalytic pyrolysis of the HSF gave an acidic oil with low viscosity and high energy content, and was nitrogen and sulfur free, whereas the catalytic pyrolysis of the solid residue after hexanes extraction (SR) gave an oil with higher viscosity, close to neutral pH, lower energy content, and had high nitrogen content and traces of sulfur.

In municipal wastewater treatment, anaerobic digestion is the slowest process requiring at least 15 day solids retention time (SRT). Treating only a small fraction of the total wastewater stream, anaerobic digesters require large reactor volumes and consistent heating (40°C). Thus, there is a growing need to investigate techniques to improve digestion efficiency. The long SRT requirement is a result of the time required for biological reactions such as hydrolysis and acetoclastic methanogenesis. There are numerous pretreatment methods which have so far been developed to particularly enhance hydrolysis. These pretreatment methods include thermalization, mechanical treatments, and chemical treatments. These methods aim to increase the degradability of the influent waste sludge which in turn will increase the efficiency of the digestion process. The goal of the research presented in this thesis is to enhance another limiting biological reaction: acetoclastic methanogenesis. Microbial electrolysis cell (MEC) technology was integrated into lab-scale anaerobic digesters in order to accelerate biosolids destruction under various SRT and temperature conditions. Various mathematical simulations were conducted using a developed steady-state ADM1 (Anaerobic Digestion Model No.1) model to further evaluate the performance of the digesters. The results of the research indicate that the proposed method is effective at shortened SRTs (e.g., 6 days) and can enhance the stability of anaerobic digestion when exposed to variations in temperature and influent composition. / Thesis / Master of Applied Science (MASc)

O método de desaguamento por leitos de drenagem foi desenvolvido por Cordeiro a partir do ano de 1993 (CORDEIRO, 2001) para o desaguamento de lodos de Estações de Tratamento de Água. A sua aplicação para lodos de lagoas de estabilização de esgotos foi feita por Fontana et al. (2007). Este trabalho teve por objetivo avaliar a utilização de leitos de drenagem no desaguamento de lodos produzidos em reatores UASB. Para tanto foram realizados ensaios em laboratório, utilizando testes do tempo de drenagem, para avaliar a influência de diferentes doses e tipos de polímeros no desaguamento do lodo. Alguns geotêxteis foram utilizados como meio filtrante nos funis de Buchner e também avaliados pelo teste do tempo de drenagem. Após escolhidas a manta e o polímero que apresentaram os melhores resultados em laboratório, foram desenvolvidos ensaios em escala piloto, com a utilização de três unidades cobertas de leitos de drenagem, cada um com dimensões de 1,58 m x 1,09 m por 0,5 m de altura. Para a avaliação do efeito das diferentes doses de polímero em escala piloto, foram utilizadas doses de polímero de 0 a 8 g/kg de sólidos totais (peso seco) e mantida a taxa de aplicação de sólidos em 15 kgST/m².ciclo (a concentração de sólidos no lodo foi de aproximadamente 27 g/L). Os resultados indicaram que com doses de polímero =2 g/kgST (peso seco) obtinha-se teor de sólidos no lodo de cerca de 13% após 1 dia e 20% após 10 a 15 dias. Para se atingir teor de sólidos de 25 a 30% o período de secagem necessário foi de cerca de 30 dias. Embora que mesmo sem a aplicação de polímeros o comportamento do lodo fosse semelhante ao de lodos condicionados com polímero, em relação à evolução do teor de sólidos em função dos períodos de secagem, observou-se certa dificuldade na remoção do lodo desaguado e principalmente na limpeza das mantas geotêxteis. Para avaliar diferentes taxas de aplicação superficial de sólidos, foram ensaiadas taxas entre 9 e 22 kgST/m².ciclo. A evolução do teor de sólidos, ao longo do período de secagem dos 3 ensaios realizados, indicou que taxas mais altas de aplicação de sólidos não diminuem as velocidades de secagem, sugerindo que, inclusive, taxas mais altas poderiam ser ensaiadas. / The method of dewatering sludge through Drainage Beds was originally developed in 1993 by Cordeiro (CORDEIRO, 2001) with sludge from Water Treatment Plants. Fontana et al. (2007) used sludge from wastewater stabilization ponds with positive results. The purpose of this research is the evaluation of the drainage bed method to dewater sludge from UASB reactors. Several laboratory trials were performed, measuring drainage times to assess the influence of different polymer types and doses on sludge dewatering. Few geotextiles were used as filter on the drainage time test to evaluate their performance. Once the polymer and the geotextile that best performed in the laboratory were chosen, several pilot experiments were performed with the use of three covered units of drainage beds, each measuring 1.58m x 1.09m (width) x 0.5m (height). For the evaluation of different polymer conditioning doses on a pilot scale, doses from 0 to 8 g/kg of total solids (dry weight) were used and the applied rate of solids kept at 15 kgTS/m².cycle (the concentration of solids in the sludge was of approximately 27 g/L). Results indicated that with the use of polymer doses =2 g/kgTS (dry weight), approximately 13% of total solids in the sludge was observed after one day, which increased to approximately 20% after 15 days. To reach 25% to 30% of total solids in the sludge, the drying time required was circa 30 days. Even without the application of polymers, the behavior of sludge in terms of total solids during the drying period was similar to the sludge conditioned with polymers. Although, with the unconditioned sludge, some difficulty to remove the dewatered sludge cake was observed, mainly in cleaning of the geotextile sleeves. In order to evaluate different application rates of solids, the pilot experiments included rates between 9 and 22 kgTS/m².cycle. The behavior of the total solids in the cake during the drying period of the three experiments suggested that the higher rates of application of solids does not reduce the drying speed, indicating that higher rates can be targeted in future research projects.