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Anaerobic processing has become recognized as a simple and energy-efficient means of treating and stabilizing many high strength organic industrial wastes and is also not subjected to the operating limitations of aerobic processes. The literature review presented in this thesis outlines the advances made in the understanding of the microbiology and biochemistry of the process and the considerable advances in reactor configurations in achieving high SRTIHRT ratios. The efficacy of the anaerobic process is dependent on maintaining a high biomass concentration in the reactor, which in tum is dependent on the performance of the solids separator. The anaerobic contact process employs gravity settling for solid-liquid separation but the poor settleability of the anaerobic sludge may result in a poor performance of the contact process. By employing a much more efficient separation process such as ultrafiltration (UF), the performance of the anaerobic system can be significantly improved. In this study, therefore, a new method of operating a completely mixed anaerobic digester using a crossflow UF membrane technique was investigated in order to control the concentration of active biomass in the reactor and to determine the extent of any other advantages that can be gained over other reactor configurations. The study was carried out in four stages. In the first stage the performance of an anaerobic contact digester using a crossflow UF membrane technique was investigated for brewery wastewater treatment. The results obtained from this stage showed that under steady-state conditions, at an influent substrate concentration of approximately 120 g COD/l (100 g BOD/I) with a hydraulic retention time of 4.2 days giving an organic loading rate of 28.5 kg COO/m3.d , overall COO and BOD removal efficiencies of 99% and almost 100% respectively were achieved and the system had not reached its maximum loading capacity. Throughout the operation, HRT was maintained in the range of 2.5-4.2 days, largely determined by the flux rate. Microbiological analyses including Microscopic Count, Plate Count, Most Probable Number and Specific Methanogenic Activity test confirmed that there was almost no biomass loss through the membrane which, in tum, resulted in the maintenance of a high stability of the system under load changes. The UF membrane showed a remarkable consistency throughout the study. retaining a high concentration of active biomass in the digester and demonstrating that fouling by anaerobic biomass will reach a limiting level. In the second stage of the study the effect of Mixed Liquor Suspended Solids (MLSS) on the kinetics of the membrane reactor was investigated. The results showed that the kinetic coefficients estimated from the four steady-state runs had slight variations from each other but which could be mainly due to the changes in the numbers and the dominant species throughout the operation of the system. The increase in the MLSS concentrations did not significantly affect the kinetics of the system, In the third stage of the study the Specific Methanogenic Activity (SMA) technique was used to determine the methane production capacity of the membrane reactor, thus allowing suitable OLRs to be applied and to assess the effects of MLSS concentration on the activity of acetoclastic methanogenic bacteria in the digester. The results showed that any deterioration in acetoclastic methanogenic capacity of the system can be improved by increasing the sludge wastage rate. Ratios of the actual methane production rate to the potential methane production rate of less than 0.7 were found to be satisfactory in order to run the system efficiently in terms of COD removal and methane yield. In the final stage of the study the possible effects that membrane systems may have on the microbial population in the reactor was investigated. Therefore, microscopic examinations have frequently been carried out in order to determine the effects of the new configuration on any variation in the morphology or on the properties of methanogens as well as any change in the number of non-methanogens throughout the operation of the membrane reactor. This investigation showed that the membrane system configuration did have an apparent effect on the dominant methanogenic species throughout operation of the membrane reactor. For example Methanococcus species were the most dominant group at the beginning of the start-up period, becoming the third most dominant group at the end of the study. As a result, studying the changes in the number of viable methanogens and the dominant species may help to determine a reason for the deterioration in performance of a digester.

The staggering levels of growth and development resulting in a more populous and affluent society that Vietnam is experiencing have resulted in greater levels of consumption and environmental damage from agricultural intensification (over-use of chemical fertilizers) and solid waste pollution. A traditional method touted as a modern solution is organic solid waste recycling and composting. This thesis seeks to determine the potential of compost use in Ho Chi Minh City, Vietnam based on a decentralized community-based composting scheme. In recent decades, in Vietnam and other developing countries, there has been an emphasis on large-scale, mechanized composting processes using mixed waste as the input material and technologies that are inappropriate for use in a developing country. These processes face high operational costs and a lower quality final product, leading to more problems than they promise to cure. This study examines three institutional models currently advocated in the literature to mange organic waste in developing countries: decentralization, privatization, public-private partnerships. This thesis focuses on how to redefine the manner in which organic waste is composted and concludes in favour of small-scale community-based composting. A small-scale community-based model currently in use in Quy Nhon, in central Vietnam is examined to determine its applicability in Ho Chi Minh City, Vietnam. The major contribution of this thesis is the use of institutional models (community-based management, decentralization, privatization, and public-private partnerships) to further understand the system of composting using municipal solid waste in developing countries. This understanding is used to present a framework that outlines the necessary institutional change to facilitate the development of initiatives that would manage organic solid waste.

IKEA of Sweden decided to set a target to keep the amount of waste low, by minimizing the amount of combustible waste to 8% of the total waste amount. IKEA Gothenburg has been having troubles with the target, since their amount of combustible waste has been twice and trice as much as the goal. Research have been done by interviews, questionnaire, random controls in the recycling area, IKEA’s own environmental education (E-learning) and observations of the everyday work. These researches have lead to a couple of suggestions and ideas. Issues that have been discussed is mainly the possibilities of changing and improving of the recycle area, engagement within the management as well as the staff, responsibility distribution and to make the profits in economics and environment visible. / IKEA Sverige har satt upp mål om att hålla avfallsnivån så låg som möjligt, genom att andelen brännbart avfall maximalt får vara 8% av den totala avfallsmängden. IKEA Göteborg har haft problem, då halten av deras brännbara avfall har legat på det dubbla respektive tredubbla i de båda varuhusen. Genom en grundlig undersökning, med hjälp av intervjuer, enkäter, stickprovskontroller i ÅVC, miljöutbildning (E-learning) samt observationer av det dagliga arbetet har en rad förslag och slutsatser dragits. Bland annat diskuteras möjligheterna till förändrat och förbättrat upplägg i ÅVC, engagemang hos ledning och personal, ansvarsfördelning, utbildning samt synliggörning av ekonomiska och miljömässiga vinster.

The staggering levels of growth and development resulting in a more populous and affluent society that Vietnam is experiencing have resulted in greater levels of consumption and environmental damage from agricultural intensification (over-use of chemical fertilizers) and solid waste pollution. A traditional method touted as a modern solution is organic solid waste recycling and composting. This thesis seeks to determine the potential of compost use in Ho Chi Minh City, Vietnam based on a decentralized community-based composting scheme. In recent decades, in Vietnam and other developing countries, there has been an emphasis on large-scale, mechanized composting processes using mixed waste as the input material and technologies that are inappropriate for use in a developing country. These processes face high operational costs and a lower quality final product, leading to more problems than they promise to cure. This study examines three institutional models currently advocated in the literature to mange organic waste in developing countries: decentralization, privatization, public-private partnerships. This thesis focuses on how to redefine the manner in which organic waste is composted and concludes in favour of small-scale community-based composting. A small-scale community-based model currently in use in Quy Nhon, in central Vietnam is examined to determine its applicability in Ho Chi Minh City, Vietnam. The major contribution of this thesis is the use of institutional models (community-based management, decentralization, privatization, and public-private partnerships) to further understand the system of composting using municipal solid waste in developing countries. This understanding is used to present a framework that outlines the necessary institutional change to facilitate the development of initiatives that would manage organic solid waste.

The work describes various physical and chemical treatments to eliminate the deleterious effects of impurities in phosphogypsum on the delayed setting time and impaired strength development behaviour of cement to which it was added as a set regulator. The physical treatments included washing, milling, and ultrasonic treatment of the material, while the chemical treatments dealt with acidic and basic additions to the phosphogypsum during the washing stage. It was found that chemical treatment with a milk of lime solution, which is often recommended in literature, was ineffective in reducing set retardation. Treatment with ammonium hydroxide or sulphuric acid was more effective in this regard. Intergrinding phosphogypsum with slaked lime improved its effectiveness in reducing set retardation, but the use of unslaked lime was less effective and also resulted in marked reductions in compressive strengths. A combined treatment of wet milling phosphogypsum with a lime slurry in a ball mall was derived from these experiments and is recommended for full-scale plant applications.