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In order to achieve the Millennium development goals of the UN, different initiatives have been established worldwide. One of these initiatives has been developed in Matagalpa, Nicaragua. Through the program Agua para Todos – Agua para Siempre different institutions work together, the common goal being to provide safe drinking water and sanitation to a large number of the people of Matagalpa and the surrounding areas. One of the ways in which this goal is pursued is by installing wastewater treatment systems for demonstration purposes in order to reduce the contamination produced by the coffee processing industry. This industry is, at present, the major cause of pollution of open water sources in the Matagalpa province. Therefore, a new hybrid anaerobic wastewater treatment system has been developed: an improved anaerobic lagoon (LAM, because of the Spanish acronym). One of the main objectives of this report is to throw light on the way in which such a system works and to also recommend to coffee farmers the set up size that is recommendable when installing a LAM system. In addition, the possibilities for locally integrating the use of biogas produced in the LAM system is a question that is discussed in this thesis. For this purpose, a LAM system has been installed in a medium‐sized coffee farm called El Socorro. In the period between November 2009 and January 2010, measurements were made of key parameters in El Socorro which indicate the efficiency and working of the LAM system, together with pre‐treatment and post‐treatment. In previous harvest seasons other students have conducted work on the characterization of coffee wastewater and this data, together with the data obtained during the last harvest season will help in providing answers to the objectives stated in the previous paragraph. During the fieldwork unforeseen restrictions were encountered which were ultimately responsible for reducing the quantity of data below that which was anticipated. However, with the information gathered, it was obvious that in the last harvest season the lack of lime for neutralizing the coffee wastewater was a serious problem that inhibited the proper working of the biomass in the LAM system. Therefore, no biogas production took place at all. The biogas production, which should have been measured during the fieldwork, could not be measured due to prolonged delays. This is why many theoretical calculations and assumptions need to be made in order to come up answers to the questions posed by this thesis. Measurements of wastewater revealed an average pH value of 4.9. In order to elevate this value, a base is needed which elevates the alkalinity of the wastewater. In this report two bases are studied: calcium hydroxide and calcium carbonate. From these two bases the conclusion is drawn that calcium carbonate, even when it has to be applied in larger quantities, has the preference due to the substantial difference in costs (US$ 0,49 cheaper per produced quintal oro). The estimated biogas production, which to a large extent had been based on assumptions concerning coffee wastewater, is much lower when measured values are used to calculate methane production. Therefore, instead of the anticipated 17.5 m3/d of CH4, only 2.4 m3/d could have been produced in the last harvest season. This production is not enough to run engines and can only at best be used to cook. If this application is not possible then the only option left is to flare the biogas. At the end of the report a graph is presented in which it is shown how different coffee farmers can get an impression of how likely the successful implementation a LAM system in their coffee farms is, which not only prevents fines (by treating the wastewater), but also renders profit from biogas production in larger quantities.

Phosphorus depletion is an emerging and serious global environmental issue. At this moment, research and policy discussion on phosphorus scarcity is still limited. This research investigates the possibilities of phosphorus recovery by controlled precipitation of struvite from digested sludge. At Waternet’s wastewater treatment plant Amsterdam West, plans for a struvite reactor are scheduled. The advantage of phosphorous recovery through struvite precipitation from digested sludge is three-fold. First, struvite can be directly used as fertilizer. Second, undesirable struvite precipitation in the wastewater treatment plant is prevented by reducing the phosphorus concentration in the dewatering reject stream which is fed back to the inlet of the treatment plant. Third, sludge dewaterability improves due to the addition of MgCl2. This thesis investigates the influence of mixing speed, aeration rate, magnesium dosing method and crystal recycle method on struvite growth and phosphorus removal, as well as separation of struvite from sludge. For that purpose, experiments have been performed in a crystallization reactor and a counter-current washing column at lab scale at wastewater treatment plant Amsterdam West. MgCl2 was added under varying reactor conditions, struvite constituent concentrations were measured and struvite growth was assessed. First, it is demonstrated that struvite recovery is well possible in a stirred sludge environment at neutral pH commonly applied in sludge digesters (7.0 - 7.1). Phosphorous removal under these circumstances is at least 85%. More complete mixing by stirring at a higher speed further improves struvite recovery by keeping supersaturation low. Secondly, a significant difference in struvite recovery was observed between experiments in which MgCl2 is dosed instantly versus experiments in which MgCl2 is dosed gradually. Gradual MgCl2 dosage, and therefore rapid mixing, improves recovery compared to instant dosage. Mixing at a higher stirring speed further improves recovery. Thirdly, it is found that struvite recovery under given circumstances is poor in a combined aerated and stirred sludge environment. In such environment higher aeration rates deteriorate struvite recovery further, while struvite recovery improves with decreasing aeration rates at a higher stirring speed. Fourthly, struvite separation experiments have verified that separation is well possible in a counter-current washing set-up, separating 86% of detectable struvite within 15 minutes at an upflow velocity of 1.3 mm/s.

Sanitation, as described by the World Health Organization (WHO), refers to the provisions of facilities and services for safe disposal of human urine and faeces. On the outset of the 21st century, 40% of the world’s inhabitants do not have access to sanitation facilities and still rely on a bucket, a bush or a backstreet for excretion. Technically, all options that are required to deal with the global sanitation problem seem to have been already developed. However, the challenge remains in selection and implementation of technologies in a way that the desirable outcomes would be resulted. Some decision-making support tools have been developed so far to address this problem by assisting the decision-makers in selecting the appropriate technologies. While decision-making is about considering the likelihood of uncertain events, in most of the existing evaluation approaches the complex task of predicting and evaluating probabilities is reduced to simple judgmental operations. Forinstance, evaluation of sanitation options is often performed based on predicting the outcomes that best represent a sanitation system, with no or little regard to the factors that limit the predictive accuracy. This thesis adopts a new evaluation approach by taking into account the real world examples from executed sanitation facilities and develops a probabilistic evaluation framework in which sanitation options are assessed based on the probabilities that specific outcomes occur in practice. Absolute judgments are replaced by probable assessments, as this approach tries to keep its distance from making the uncertain certain. Although there may be a hidden consensus that quantification of occurrence probabilities for various outcomes of sanitation options is not always possible, some quantification methods are developed and presented in this thesis for all the assessment criteria. Moreover, this thesis does not only focus on making the decisions, but also tries to channel the decisions in a way that the negative outcomes of sanitation facilities would be reduced through the measures that could be taken to improve the performance of sanitation options. By applying the probabilistic evaluation approach for decision-making about sanitation facilities in low-income unplanned slum settlement of Nyalenda in Kisumu, Kenya (based on limited available data about this region in literature) it is indicated that while a sanitation option may be known for fulfilling a certain task by definition, through a probabilistic evaluation it may be revealed that the local conditions are not likely to allow the expected outcome to occur in practice and as a result this option would have no priority among other options. The necessity for monitoring and post-evaluation of implemented sanitation projects in order to have sufficient feedback for improvement of future decisions is also highlighted.

Membrane fouling problem is one of the most crucial issues which restricts the development of MBR and is, therefore, the prime research topic for many researchers worldwide. Anaerobic MBRs offer interesting perspectives as a potential solution for the treatment of wastewaters under extreme conditions, e.g. high temperature and/or high salt content, However, the research on membrane fouling of AnMBR system is still limited. Therefore, in this Master Thesis the research is focused on the flux determining conditions of AnMBR systems in hyper saline environment. Hyper saline environment is those containing salt concentration in excess of seawater which is 35g/l. The conditions of AnMBR in hyper saline environment are quite different from aerobic MBR system, so the measures applied in aerobic MBRs to prevent membrane fouling may not be useful in AnMBRs in hyper saline environment. In the first series of experiments of this thesis work, the efficiency of existing measures, which are applied in full-scale aerobic MBRs to prevent membrane fouling, are evaluated for application in AnMBRs under hyper saline conditions. Because the concentration of NaCl in hyper saline wastewater is quite high and NaCl can be used as flocculant (Mietta et al., 2009), one of the experiments was designed to induce proper shear force to the AnMBR reactor to test whether this manner could alleviate membrane fouling. Unfortunately, the result of this experiment was negative and membrane fouling was still serious. Then LCFA was added to the reactor to check its short-term effect on alleviating membrane fouling (Stumm and Morgan, 1995). The result showed that LCFA could not reduce membrane fouling within short time. Because the results of these measures in alleviating membrane fouling in AnMBR in hyper saline environment were not satisfactory, the second series of experiments of this thesis work were designed to analyse the foulant constituents of AnMBRs in hyper saline environment and their characteristics. The results of the second series experiments showed that sodium, calcium, iron and potassium were the main metal ions in cake layer. Likely, ion-exchange activities between calcium ions in the cake layer and sodium ions in the liquid phase were apparent under the hyper saline conditions in lab-scale AnMBR experiment. The functional groups of organic foulants on the fouled membrane were alkanes, carboxylic acid, nitro compounds, alkyl halides and alkenes in this research and chemical cleaning could only remove part of organic foulants.

Introduction: The research was performed in two rural sites in Thailand and Laos. The Diarrhea and Dengue (DIADEN) group from the Norwegian University of Life Sciences facilitated the fieldwork. In the Thai site, rainwater was the main drinking water source, whereas in Lao site, unprotected dug well was predominant in dry season and was replaced by rainwater in wet season. Drinking water was largely consumed untreated. Combined with varying sanitation service and hygiene behavior, it was assumed that the safety of drinking water might be compromised. Problem definition: The global monitoring of the MDG target to halve the population without safe drinking water access is performed by the Joint Monitoring Programme (JMP). The JMP uses technological classification (improved or unimproved sources) as monitoring indicator for water safety. This has been criticized for being inadequate in representing the actual conditions in water provision. The core argument is that drinking water quality at improved sources might not necessarily be free from pathogens. In addition, drinking water that is safe at the sources might as well be recontaminated through various water handling practices, particularly where manual collection, transport and storage are common. Thus, in this study it is proposed that the technological classification is refined through the use of a semi-quantitative hazard classification system. Research: In the first part, the research was focused on the identification and classification of the hazards found at the various water sources and the hazards related to sanitation facility and hygiene behavior. This was achieved through sanitary inspection, household questionnaire and spot observation carried out in about two weeks time. In the second part, water samples were collected twice at selected sources and household drinking containers. Samples were tested for E. coli as faecal indicator organisms, using the standard Colisure/Ouanti-tray 2000 method from IDEXX. The water quality data were then used to validate the hazard classification systems. Simultaneously, a new E. coli enumeration method, the Compartment Bag Test (CBT) by University of North Carolina, was used in parallel to investigate the comparability of the two tests. Results: 1. The first investigation found that the hazards in Laos were more severe than in Thailand. 2. Water quality of the rainwater source (improved) was variably contaminated. The unprotected dug well (unimproved) was grossly contaminated. 3. Water quality at the household containers was also variable. Overall, there was significant deterioration of water quality from sources to households that can be attributed to household water handling practices (e.g. extraction methods, cleanliness, treatment). 4. The hazard classification system for water sources in Laos was moderately correlated with water quality data and was not significantly correlated for Thailand. The sanitation and hygiene hazards were not significantly correlated in both sites. 5. The CBT data was significantly different from the Colisure/Quanti-tray 2000 data. Conclusions and recommendations: The JMP indicator overestimates water safety both at sources and at households. The hazard classification system, if refined further with weighted-scoring and long-term water quality data, might enable a more accurate representation of the actual conditions. Correlations with health impacts are also recommended. Furthermore, manual water handling practices compromises water quality and it is thus advised to eliminate hand-water contact as much as possible.

Despite continuous developments in the field of MBR technology, membrane fouling together with the associated energy demand and related costs issues remain major challenges. The efficiency of the filtration process in an MBR is governed by the activated sludge filterability, which is still limitedly understood and is determined by the interactions between the biomass, the wastewater and the applied process conditions. The purpose of this thesis is to increase understanding of the factors impacting activated sludge filterability during full-scale membrane bioreactor (MBR) operation. The overall research goal was to determine conditions for enhanced and efficient operation of the MBR technology. The research work included both extended on-site measurements and operational data analysis. Filterability of the activated sludge was experimentally determined in full- and pilot-scale MBRs treating both municipal and industrial wastewater. Subsequently, the most influential parameters influencing activated sludge filterability were determined. In addition, the design, operational and performance data were collected from the selected full-scale MBR plants and analysed in respect to plant functioning, i.e., operation, energy efficiency and operational costs. Therefore, the research links activated sludge filterability assessment and full-scale MBR functioning, i.e., design options, operation, performance and energy efficiency. Overall, it can be concluded that good filterability of the activated sludge is indispensable for efficient and optimal operation of an MBR. Operation with poor sludge filterability will be associated with a cost penalty due to sub-optimal filtration conditions. Wastewater composition and temperature are important influencing parameters with respect to filterability. MBR plant layout and membrane configuration influence overall MBR functioning and should be chosen carefully. The energy efficiency of an MBR is driven by the hydraulic utilization of the membranes and can be improved by implementation of flow equalization, new aeration strategies and adjusting operational settings to the incoming flow.