Digestate from Manure Recycling Technologies

Rapid economic development and population growth help making the management of solid waste one of the Egyptian most critical environmental issues. A solar drying system is designed and tested for managing different waste residuals resulting from the food processing techniques. The suggested solar dryer dehydrated the samples to 7, 20, 28 and 35% (wet b asis) moisture content for Jew's mallow (Mouloukhia), carrots residuals, tomato seeds and tomato peel, respectively in 7 hours at 34-93°C inside the solar dryer, while the ambient temperature was 28-42°C.

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În cadrul gestiunii deşeurilor solide urbane (DSU), în concordanţă cu noile directive Europene cu privire la recuperarea materialelor şi valorizarea lor energetică, o nouă opţiune bazată pe trateatea bio-mecanică (TBM) cu flux unic a deşeurilor solide urbane este în continuă devoltare. Acest process de tratare poate fi utilizat atât ca un pretratament înaintea depozitării controlate sau /şi înaintea combustiei. In acestă lucrare se prezintă anumite aspecte ştiinţifice legate de introducerea acestui tratament bio-mecanic în România şi a utilizării Combustibilului Derivat din Deşeuri (CDD), în instalaţii industriale, cu minimizarea volumului necesar depozitării. Rezultatele au fost obţinute în cadrul unei colaborări ştiinţifice dintre

Energies, 2019

The use of biogas plants has increased sharply in recent years. A typical biogas plant of 500 kWel produces approx. 10,000 t of digestate per year, with a moisture content of more than 90%. For the purpose of reducing the transport mass and increasing the nutrient concentration, the digestate has to be dried. Using renewable energy is a way to treat biogas digestate without any additional fossil energy requirement for drying. In this study a solar greenhouse dryer was modified to use additional waste-heat from the combined heat and power unit (variant S-CHP), as well as the exhaust gas from a micro turbine (variant S-CHP-MT). The hybrid waste-heat/solar dryer achieved a moisture content for the digestate of 10.9%, and 10.5%, after 13 d of drying for variant S-CHP-MT and S-CHP-MT, respectively. Due to the higher energy input by additional use of the micro turbine, the specific energy consumption is higher for the variant S-CHP-MT. In general, the results showed that the combination o...

Renewable Energy, 2006

The Solar Energy Research Group in the Universiti Kebangsaan Malaysia has been set-up more than two decades ago. One of the activities is in the field of solar thermal process, particularly in development of solar assisted drying systems. Solar drying systems technical development can proceed in two directions. Firstly simple, low power, short life, and comparatively low efficiency-drying system. Secondly, the development of high efficiency, high power, long life expensive solar drying system. The group has developed four solar assisted drying systems namely (a) the V-groove solar collector, (b) the double-pass solar collector with integrated storage system, (c) the solar assisted dehumidification system for medicinal herbs and (d) the photovoltaic thermal (PVT) collector system. The common problems associated with the intermittent nature of solar radiation and the low intensities of solar radiation in solar thermal systems can be remedied using these types of solar drying systems. These drying systems have the advantages of heat storage, auxiliary energy source, integrated structure control system and can be use for a wide range of agricultural produce.

2008

The proposed solar thermodynamic drying system reduces the traditional dehydration process of Roselle used in the western region of Mexico, from approximately four days to four hours. In addition to the 95% reduction in process time, this system also maintains the Roselle's nutritional content, especially that of ascorbic acid (Vitamin C). The proposed drying system is based on current operating

2020

The EU27 annually generates 90 Mt of food waste, and approximately 40 % of this waste is generated during manufacturing. The food processing industry needs to develop improved and sustainable solutions for waste valorisation and re-use. The project DRALOD addresses this issue since it aims at design, integration and assessment of the performance of a heat recovery system in connection with an innovative low-temperature air drying unit where high moisture food waste is dewatered and sold as a by-product with preserved nutritional ingredients. The air used for drying is preheated using solar heat and a biomass boiler, and in this project the potential benefits of integration of a heat recovery system have been investigated. Due to the impurities available in the humid exhaust air from the dryer, the heat recovery is designed with two principal systems; a wet scrubber condensation system and a heat pump system. Simulations using hourly meteorological data from Madrid have been made for...

The objective of this study was to evaluate the performance of a solar assisted dehumidification system. This system as incorporation of two columns of desiccant beds into a solar drying system. The main components of the a solar assisted dehumidification system consist of a solar collector, an energy storage tank, an auxiliary heater, two blowers, two columns of desiccant beds (adsorber columns), two water-air heat exchanger, two water circulating pumps, a drying chamber and other ancillary equipment. Silica gel was selected as the desiccant material due to low temperature regeneration. The performance of this system has been investigated under the meteorological condition of Malaysia. A computer program was developed in MATLAB software to calculate the performance of the drying system. The performance indices considered to calculate the performance of the drying system are: Pick up efficiency (P η), Solar Fraction (SF) and Coefficient of Performance (COP). The results indicated that the maximum values of the pick up efficiency (P η), solar fraction (SF) and coefficient of performance (COP) was found 70%, 97% and 0.3, respectively with initial and final wet basis moisture content of Centella Asiatica L 88% and 15%, respectively at an air velocity is 3.25 m/s.

Digestate from the biogas digestion process contains high amounts of water and nitrogen, which can lead to over-fertilization problems in regions with intensive livestock farming due to a surplus of ammonium, which contributes to the global warming effects. The best option to reduce thewater content aswell as to concentrate the nitrogen is to dry digestate; however, volatile nitrogen present in the digestate has the tendency to be emitted. Therefore, the objective of this study was to investigate the emissions of untreated and dewatered digestate during the drying process and to determine the nitrogen loss of the drying product by calculating the loss over time by the emissions and compare it with initial and final ammonium content made by chemical analysis. The drying procedure was performed in a hybrid waste-heat/solar dryer.Ammoniaratewas measured continuously during drying by Fourier transform infrared spectroscopy. Untreated digestate showed higher cumulative emissions of ammonia (25.9 gNH3 kgDM −1) than dewatered material (7.75 gNH3 kgDM −1) due to lower water content and shorter drying time. Emissions fromthe filtratemay still be an issue, which should be addressed in future studies.

Food spoilage is one of the critical problems the world is facing today. A majority of food spoilage is happening in the post-harvest period due to inadequate storage and processing facilities. Cold storage is a good option but it is very much expensive and energy intensive. Hence food drying comes to lime light. Drying is one of the oldest methods used for food preservation. It is method by which the moisture will be removed, thereby restricting microbial and fungal growth. Direct sun drying has some disadvantages like exposure to dust, colour change, pigmentation, insects attack etc. Use of fossil fuel derived energy for drying has been used for getting good quality products. But fossil fuel usage is too costly and will add up to the energy demand and climate problems. Hence, solar drying is best suited sustainable way for food drying. This paper explains the concept of solar drying with case studies and economic feasibility is also discussed.

In a developing country like India, having the second largest population and agriculture as the source of income to nearly 60 % of the total population, post-harvest and storage loss is a major quandary, which needs to be addressed in due diligence. Many food preservation techniques like cold storage, drying, etc., have been evolved out over the years to tackle the above losses. The major constraint is that almost all the technologies are utilizing fossil fuel resources, which are depleting very fast and wise use of these precious resources are preferred for long-term energy sustainability. Therefore, sustainable methods for food preservation are the need of the hour. Solar drying is one of the best choices in this context. Different models of solar dryers have been developed and good quantum of research is progressing in most of the countries to propagate the solar drying technology for value addition of agriculture products. The solar drying technology is a classical example to showcase how sun’s free energy could be effectively utilized for the benefit of mankind. This chapter explains the different types of dryers, different aspects of solar drying, parameters involved in the drying process and the economic analysis to analyse the feasibility of the solar drying system. Case studies of a few of the successful installations are also included.