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Problem statement. Analysis of the treatment facilities efficiency in sewerage at the stage of their design is great importance. Also, at the stage of structures’ reconstruction or their operation adjustment under different load conditions, it is necessary to know the efficiency of water treatment in different areas of treatment facilities. Such information makes it possible to rationally operate facilities. For solving problems of this class, the most effective tool is the use of the numerical modeling method. The work considers development of numerical models set for solving problems of this class. Methodology. Two fundamental models are used to solve the velocity field determination of the wastewater flow in the sewage treatment plant. The first is a model of the vortex-free motion for an incompressible fluid. The second model is the Navier-Stokes equations written in Helmholtz variables. The mass transfer equation is used to determine impurity concentration fields in sewage treatment plants, which takes into account flow velocity, diffusion and the presence of impurity emission sources. Material balance equations for the substrate and activated sludge are used to calculate the process of biological wastewater treatment. Finite-difference schemes are used to build numerical models that allow calculating the hydrodynamics of the flow and the distribution of the impurity concentration in the facility. The Euler method is used for the numerical solution of the material balance equations. Results. Numerical models were built, which were used to develop a complex of computer programs. These computer programs allow real-time analysis of the water treatment efficiency in the facility. Scientific novelty. Numerical models have been developed that allow investigating the process of water treatment in facilities of the «settler» type and in aeration tanks, that is, for a significant class of treatment facilities used in practice. Practical value. The calculation time of the velocity field and the impurity concentration field in a water treatment plant with a complex geometric shape is few seconds. This allows usinge the developed numerical models for serial calculations in project organizations in daily work., Постановка проблеми. Аналіз ефективності роботи очисних споруд у системах водовідведення на етапі їх проєктування має велике значення. Також на етапі реконструкції споруд або налаштування їх роботи в умовах іншого навантаження потрібно знати ефективність очистки води на різних ділянках очисних споруд. Така інформація дає можливість раціонально експлуатувати споруди. Для розв’язання задач даного класу найбільш ефективний інструмент – це метод чисельного моделювання. В роботі розглянуто побудову комплексу чисельних моделей для розв’язання задач даного класу. Методологія. Для розв’язання задачі гідродинаміки – визначення поля швидкості потоку стічних вод в очисній споруді – використовуються дві фундаментальні моделі. Перша – модель безвихрового руху нестисливої рідини. Друга модель – рівняння Нав’є–Стокса, що записані у змінних Гельмгольца. Для визначення полів концентрації домішки в очисних спорудах використовується рівняння масопереносу, що враховує швидкість течії, дифузію, наявність джерел емісії домішки. Для розрахунку процесу біологічного очищення стічних вод використовуються рівняння матеріального балансу для субстрату та активного мулу. Для побудови чисельних моделей, що дозволяють розрахувати гідродинаміку потоку та розподіл концентрації домішки в споруді, використовуються скінченорізницеві схеми. Для чисельного розв’язання рівнянь матеріального балансу застосовується метод Ейлера. Результати. Побудовано чисельні моделі, що були використані для розробки комплексу комп’ютерних програм. Ці комп’ютерні програми дозволяють у режимі реального часу аналізувати ефективність очистки води у споруді. Новизна. Розроблено чисельні моделі, що дозволяють досліджувати процес очистки води в спорудах типу «відстійник» та в аеротенках, тобто для значного класу очисних споруд, що використовуються на практиці. Практична цінність. Час розрахунку поля швидкості та концентраційного поля домішки в очисній споруді, що має складну геометричну форму, складає декілька секунд. Це дозволяє використовувати розроблені чисельні моделі для серійних розрахунків у проектних організаціях у щоденній роботі.

The problem of resource saving is particularly relevant for household waste removal systems and sewage networks in modern residential houses. Some options for the shared use of sewage networks and natural organic waste removal systems in residential buildings are assessed by the author. Layouts, operation patterns and elements of the systems are provided. Strengths of shared operation of the systems and networks are analyzed with account for the present-day requirements applicable to the systems in question. The positive factor is that residents do not need to spend money for expensive food waste disposers for their homes. They will also use garbage chutes in their houses.Joint operation of food waste removal systems and domestic sewage networks will reduce the load on landfills which has been increasing in the recent years. It will increase the load on urban sewage networks and water treatment facilities, but it will not be a critical factor, because treatment facilities are capable of purifying water without much difficulty. Processed food waste may be applied to produce fertilizers and biogas to be used as fuel. Therefore, benefits of the limited use of landfills are obvious.Waste shredding is the most convenient, efficient and nature friendly way of processing the organic waste at the initial stage of its generation. It prevents rotting typical for the organic waste if disposed together with the municipal solid waste.The experience of the United States, where food waste is treated by in-sink food erators and removed into the sewage system is less expensive for city budgets than their disposal at landfills.Food wastes consist mainly of the water (70 %); therefore, water treatment facilities assure a more natural way of processing this type of waste than waste collection and disposal. Separation of organic waste from solid waste also reduces the number of disease vectors such as flies, rodents, and cockroaches.В современных домах проблемы ресурсосбережения выходят на первое место в таких системах, как канализация и мусороудаление. Рассмотрены варианты совместной работы канализации и мусороудаления по сплаву органического мусора из жилых зданий. Приведены компоновочные схемы и элементы. Показаны основные преимущества таких решений с учетом современных требований.

Carbon Capture and Storage (CCS) should be a key technology in order to achieve a decline in the CO2 emissions intensity of the power sector and other intensive industry, but this potential deployment could be restricted by cost issues as the International Energy Agency (IEA) in their last projections (World Energy Outlook 2013) has considered only around 1% of global fossil fuel-fired power plants could be equipped with CCS by 2035. The SiteChar project funded by 7th Framework Programme of European Commission gives the opportunity to evaluate the most influential parameters of techno-economic evaluations of four feasible European projects for CO2 geological storage located onshore and offshore and related to aquifer storage or oil and gas reservoirs, at different stages of characterization. Four potential CO2 storage sites have been assessed in terms of storage costs per tonne of CO2 permanently stored (equivalent cost based). They are located offshore UK, onshore Denmark, offshore Norway and offshore Italy. The four SiteChar techno-economic evaluations confirm it is not possible to derive any meaningful average cost for a CO2 storage site. The results demonstrate that the structure of costs for a project is heterogeneous and the storage cost is consequently site dependent. The strategy of the site development is fundamental, the technical choices such as the timing, rate and duration of injection are also important. The way monitoring is managed, using observation wells and logging has a strong impact on the estimated monitoring costs. Options to lower monitoring costs, such as permanent surveys, exist and should be further investigated. Table 1 below summarizes the cost range in Euro per tonne (Discount Rate (DR) at 8%) for the different sites, which illustrates the various orders of magnitude due to the specificities of each site. These figures have how to be considered with care. In particular the Italian and Norwegian sites present very specific features that explain the high estimated costs. For the Italian site, the short duration of CO2 injection associated with a low injection rate makes the CO2 project comparable to a demo project. The Norwegian site is an offshore site located in a virgin area with high infrastructure costs and a combination of injection duration and injection rate that makes the derived costs very sensitive to the discount rate. The results for both UK and Danish sites confirm therefore the value range calculated by the European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP). The main uncertainties in the costs are linked both to the choice of economic parameters (e.g. injected quantities, contingencies) and to the technical choice of operations. This has been studied by sensitivity analyses: for example, if an injection rate is halved and the injection duration is doubled, the Equivalent Storage Cost (ESC) increases by 23% (UK case at 8% DR). Introducing a water production well and water treatment facilities also increases the ESC by 23%, at least on an onshore site. Techno-economic assessments were basically carried out using an 8% discount rate. For projects of long lifetime such a rate severely discounts the late cash flow, especially after 40 years, so that a discount rate of around 4% more in logic of public investment. Compared to other studies, it has to be noted that the scope of the SiteChar analysis does not consider compression and pumping cost, nor transportation cost. This simplifies the techno-economic evaluation but it may not adequately reflect the specific conditions of the individual developments and, hence, distort the comparison between different cases. Lastly, techno-economic evaluation poses questions to policy makers about the real lifetime of a CO2 storage project: what should be the abandon phase and the associated cost and what is the real value of the liability transfer after 20 years of storage? This issue is still an open question, which has been addressed in SiteChar assuming the same approach as ZEP (2011). To counterbalance these CO2 storage costs, policy makers have to set up incentives, either through ETS (Emission Trading System) credits, tax credits or public funding. To improve the commerciality of CCS, Enhanced Oil Recovery (EOR) should be taken into account in the regulation of CCS, as it is one of the rare sources for revenue from a commodity with a real market value. CO2 storage in a saline aquifer close to oil and gas fields could also be considered as a source for CO2 EOR.

Carbon Capture and Storage (CCS) should be a key technology in order to achieve a decline in the CO2 emissions intensity of the power sector and other intensive industry, but this potential deployment could be restricted by cost issues as the International Energy Agency (IEA) in their last projections (World Energy Outlook 2013) has considered only around 1% of global fossil fuel-fired power plants could be equipped with CCS by 2035. The SiteChar project funded by 7th Framework Programme of European Commission gives the opportunity to evaluate the most influential parameters of techno-economic evaluations of four feasible European projects for CO2 geological storage located onshore and offshore and related to aquifer storage or oil and gas reservoirs, at different stages of characterization. Four potential CO2 storage sites have been assessed in terms of storage costs per tonne of CO2 permanently stored (equivalent cost based). They are located offshore UK, onshore Denmark, offshore Norway and offshore Italy. The four SiteChar techno-economic evaluations confirm it is not possible to derive any meaningful average cost for a CO2 storage site. The results demonstrate that the structure of costs for a project is heterogeneous and the storage cost is consequently site dependent. The strategy of the site development is fundamental, the technical choices such as the timing, rate and duration of injection are also important. The way monitoring is managed, using observation wells and logging has a strong impact on the estimated monitoring costs. Options to lower monitoring costs, such as permanent surveys, exist and should be further investigated. Table 1 below summarizes the cost range in Euro per tonne (Discount Rate (DR) at 8%) for the different sites, which illustrates the various orders of magnitude due to the specificities of each site. These figures have how to be considered with care. In particular the Italian and Norwegian sites present very specific features that explain the high estimated costs. For the Italian site, the short duration of CO2 injection associated with a low injection rate makes the CO2 project comparable to a demo project. The Norwegian site is an offshore site located in a virgin area with high infrastructure costs and a combination of injection duration and injection rate that makes the derived costs very sensitive to the discount rate. The results for both UK and Danish sites confirm therefore the value range calculated by the European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP). The main uncertainties in the costs are linked both to the choice of economic parameters (e.g. injected quantities, contingencies) and to the technical choice of operations. This has been studied by sensitivity analyses: for example, if an injection rate is halved and the injection duration is doubled, the Equivalent Storage Cost (ESC) increases by 23% (UK case at 8% DR). Introducing a water production well and water treatment facilities also increases the ESC by 23%, at least on an onshore site. Techno-economic assessments were basically carried out using an 8% discount rate. For projects of long lifetime such a rate severely discounts the late cash flow, especially after 40 years, so that a discount rate of around 4% more in logic of public investment. Compared to other studies, it has to be noted that the scope of the SiteChar analysis does not consider compression and pumping cost, nor transportation cost. This simplifies the techno-economic evaluation but it may not adequately reflect the specific conditions of the individual developments and, hence, distort the comparison between different cases. Lastly, techno-economic evaluation poses questions to policy makers about the real lifetime of a CO2 storage project: what should be the abandon phase and the associated cost and what is the real value of the liability transfer after 20 years of storage? This issue is still an open question, which has been addressed in SiteChar assuming the same approach as ZEP (2011). To counterbalance these CO2 storage costs, policy makers have to set up incentives, either through ETS (Emission Trading System) credits, tax credits or public funding. To improve the commerciality of CCS, Enhanced Oil Recovery (EOR) should be taken into account in the regulation of CCS, as it is one of the rare sources for revenue from a commodity with a real market value. CO2 storage in a saline aquifer close to oil and gas fields could also be considered as a source for CO2 EOR.

The involvement of the rural private sector in water supply in Cambodia is unique to the country. The presence of this private sector allows other entities to respond to new demands from people living in the larger villages for household water supply, which the State is not yet able to address. These entrepreneurs operate on a merchant basis, lacking an institutional structure which is still being created. Their business is most often based on pushcart delivering water barrels at the house of villagers or more recently on small piped networks usually distributing raw surface water. Service is rough; the water quality is uncertain, but the users are satisfied with this service, because for them, it constitutes another alternative to the already considerable choice of water supplies available-ponds, wells, boreholes, and rivers. Their demands focus more on a practical objective (a supply in the household) than on a sanitary one, even if surveys show that villagers have a good understanding of health risks associated with water. Through the implementation of 14 small scale water supply systems, the goal was to enhance a qualitative improvement of the water service in some Cambodian small towns through the transformation of rough and informal merchant services to a basic water service supplying drinking water to an extended population under a formal institutional arrangement. The MIREP (Mini Reseaux d'Eau Potable - Small Scale Piped Water Supply System) program, launched in 2001 to transform these very basic initiatives into basic services, began as a pilot project supporting one entrepreneur in the implementation of a small piped water system. In order to move forward, the MIREP program made a choice, in particular linked to its proximity to the Ministry of rural development, to assist the nascent involvement of communes in decentralization, to strengthen provincial power through the process of decentralization, and to respect the cultural heritage of those who devised and financed the project.