Study of forced aeration system for fruit and vegetable waste composting

Composting of fruit and vegetable waste (FVW) was investigated in a forced aeration system to determine the effects of aeration rate (AR) and aeration method (AM) on compost quality. Rice husk was mixed with FVW as bulking agent to compost for seven days and aerated in continuous and intermittent at rates of 0.3, 0.6, and 0.9 L min−1. Intermittent aeration at rate of 0.3 L min−1 was observed to have higher initial temperature increasing rate and peak temperature compared to continuous aeration. Moisture loss at rate of 0.3 L min−1 was found smaller than other two rates regardless of AM. With comparison made for similar AR, intermittent aeration had experienced less moisture loss with an average of 17.15 %. The pH of compost was found to vary in aeration method where higher peak pH was found in intermittent aeration at low rate, corresponding to their temperature profile. Largest carbon-to-nitrogen (C/N) ratio reduction was attained by compost treated in intermittent aeration at rate of 0.3 L min−1. Further optimization was performed at a rate of 0.1 L min−1, 0.2 L min−1, and 0.4 L min−1. The result showed an improvement at rate of 0.2 L min−1 in intermittent aeration.

Effect of external heat source on temperature and moisture variation for composting of food waste

This paper investigates the outcome of having an external heat source on temperature and moisture variations in the food waste composting process. Food waste accumulation is a growing concern in many countries. Converting food waste into usable compost is a more desirable tactic than dumping to crowded landfill sites. Closed composting was applied in this work, which relies on a controlled but uninterrupted airflow during the organic material degradation process. However, undesirable odour released at low aeration rate due to low temperature and high moisture content found in the compost. Finding the ideal aeration rate with the least possible loss of moisture is needed, which was discussed in this paper. The vegetable-fruit waste used in the experiment was given an aeration rate of 0.3 L/min at a moisture setting of 60% and 70%. For 15 mins/day, the forced aeration was carried out at 3-day intervals. Results showed that 0.3 L/min with 60% and 70% moisture content attained best temperature peaks of 32.4°C and 31.6°C, respectively at day 13 for 28 days composting. A strong odour continued to exist with the compost and was mitigated by using an external additional heat source (light bulb). The light bulb also helped to provide a higher temperature for the compost of 41.5°C by day 1 for 10 days composting.

Separation of waste plastic resulting from electrical products by forced aeration flotation

The separation of four waste plastic samples - Polyvinyl chloride (PVC), Acrylonitrile butadiene styrene (ABS), Polycarbonates (PC), and Polyamides (PA) resulting from electrical products in three bicomponent plastic mixtures (PVC-ABS, PVC – PA, and PVC - PC) was performed by using four different flotation solutions (5%, 10%, 20%, and 30% concentration) of CaCl2. Furthermore, the waste plastic samples were analyzed in terms of density, specific volume, particle size, initial water content, and water absorption capacity, while the flotation solutions were analyzed in terms of pH, density, electrical conductivity, and refractive index. Results showed that from the analyzed waste plastic samples, the PVC sample has the highest density (1.3823 g/cm3), followed by PC (1.2034 g/cm3) and PA (1.0607 g/cm3), while the ABS (0.9723 g/cm3) presented the lowest value. The highest recovery rate was obtained for the PVC samples (98.10 % - 99.75 %) when it was mixed with ABS, whereas the highest purity was measured for ABS samples (98.29 % - 99.76%) in the case of the same mixture.

PROSPECTS FOR THE USE OF AN ELECTRONIC CONTROL UNIT FOR GRAIN AERATION IN SEALED CONTAINERS WITH A CONTROLLED AIR ENVIRONMENT

Проблема и цель. В период хранения зерна в нем происходят сложные физиологические процессы, которые могут сопровождаться изменением температуры и влажности зерновой массы, интенсивным развитием в ней микроорганизмов и насекомых-вредителей и т. д. Для недопущения подобных явлений в зернохранилищах используются системы активной вентиляции (САВ) зерновой насыпи. Для повышения эффективности работы САВ в странах Северной Америки и ЕС используют сложные электронные блоки управления (ЭБУ), которые на порядок дороже простых и требуют для их программирования высокой квалификации обслуживающего персонала. Поэтому на сегодняшний день наиболее перспективным направлением развития автоматических систем управления вентиляционными установками зернохранилищ является использование простых ЭБУ в комплекте с комбинированными электронными контрольно-измерительными устройствами (датчиками). Целью настоящего исследования было сравнение эффективности работы систем активного вентилирования в металлическом силосе и принудительной аэрации в контейнере с регулируемой газовой средой за счет применения простых ЭБУ при хранении семенного зерна. Методология. В качестве объекта исследования были взяты технологии управления системой активного вентилирования с использованием простых ЭБУ и принудительной аэрации зерновой насыпи в контейнере с регулируемой газовой средой, управляемой ЭБУ в комплекте с комбинированными электронными контрольно-измерительными устройствами. Образцами для исследования служили семена яровой пшеницы «КВС Аквилон», полученные от пересева элитных семян третьего поколения категории РС-3. В ходе сравнительных испытаний оценивалось влияние исследуемых технологий на условия хранения семенного зерна и жизнедеятельность насекомых-вредителей. Результаты. Применение САВ в металлических силосах с автоматическим управлением простым ЭБУ не обеспечивает достаточной сохранности посевных качеств семенного зерна. Так, как в процессе его сезонного хранения не исключена вероятность образования конденсата влаги на внутренней стенке силоса, отпотевания зерна, наблюдался рост популяции насекомых- вредителей. Замена САВ на систему принудительной вентиляции в контейнере с регулируемой газовой средой, управляемую ЭРУ на основе микропроцессора Arduino UNО и комбинированных датчиков-регистраторов температуры и влажности воздуха DT 171, позволяет сохранить репродуктивные свойства семян, при этом более интенсивно проводить охлаждение зерна за счет естественного теплообмена с окружающей средой и сократить более чем в 20 раз популяцию насекомых-вредителей. Заключение. Применение контейнеров с регулируемой воздушной средой, управляемой работой ЭБУ на основе микропроцессора Arduino UNО и комбинированных датчиков-регистраторов температуры и влажности воздуха DT 171, позволяет сохранить посевные качества зерна, при этом снизить затраты электроэнергии и трудоемкость выполнения работ, проводить эффективную борьбу с насекомыми-вредителями за счет разрежённости воздушной среды. Problem and goal. During the period of grain storage, complex physiological processes occur in it, which can be accompanied by changes in the temperature and humidity of the grain mass, the intensive development of microorganisms and insect pests in it, etc.To prevent such phenomena in granaries, active ventilation systems of the grain embankment are used. To improve the efficiency of the SAA in North America and the EU, complex electronic control units are used, which are much more expensive than simple ones and require highly qualified service personnel to program them. Therefore, to date, the most promising direction of development of automatic control systems for ventilation installations of grain storage facilities is the use of a simple EBU complete with combined electronic control and measuring devices (sensors). The purpose of this study was to compare the efficiency of active ventilation systems in a metal silo and forced aeration in a sealed container with a controlled air environment through the use of simple ECUs in the storage of seed grain. Methodology. As the object of research, the technologies of controlling the active ventilation system using simple ECUs and forced aeration of the grain mound in a sealed container with a controlled air environment controlled by the ECU, complete with combined electronic control and measuring devices, were taken. The samples for the study were the seeds of spring wheat "KVS Aquilon", obtained from the re-sowing of elite seeds of the third generation of the RS-3 category. In the course of comparative tests, the influence of the studied technologies on the storage conditions of seed grain and the vital activity of insect pests was evaluated. Results. The use of SAV in metal silos with automatic control of a simple ECU does not provide sufficient safety of the sowing qualities of seed grain. Since in the process of its seasonal storage, the probability of the formation of moisture condensation on the inner wall of the silo, the sweating of grain, an increase in the population of insect pests was observed. Replacing SAV with a forced ventilation system in a sealed container with a controlled air environment controlled by ERU based on the Arduino UNO microprocessor and combined sensors-recorders of temperature and humidity DT 171, allows you to preserve the reproductive properties of seeds, while more intensively cooling the grain due to natural heat exchange with the environment and reducing the population of insect pests by more than 20 times. Conclusions. The use of sealed containers with controlled air mediumcontrolled operation of the ECU based on the Arduino UNO microprocessor and combined sensors-recorders of air temperature and humidity DT 171 allows you to preserve the sowing quality of grain, while reducing the cost of electricity and labor intensity of work, to effectively combat insect pests due to the sparsity of the air environment

Production of Lignocellulolytic Enzymes and Biomass of Trametes versicolor from Agro-Industrial Residues in a Novel Fixed-Bed Bioreactor with Natural Convection and Forced Aeration at Pilot Scale

Solid-state fermentation requires the development of more efficient cultivation systems for its industrial application. The objective of this work was to evaluate the effect of aeration regime on the production of biomass and several lignocellulolytic enzymes (laccase, manganese peroxidase, endoxylanase, β-glucosidase, and total cellulases) by Trametes versicolor in a novel fixed-bed solid-state pilot-scale bioreactor. Three regimes were assessed: natural convection, low aeration level (10 min every 6 h at 10 L/h air flowrate), and high aeration level (1 h every 6 h at 10 L/h air flowrate). The mushroom was grown on a medium based on lignocellulosic residues. The design of the bioreactor, as well as the control of aeration, humidity, and temperature of the beds, allowed T. versicolor to grow properly on the medium, reaching a maximum biomass production of 204.7 mg/g dry solid (ds). The influence that aeration regime had on the production of lignocellulolytic enzymes was determined. Low level of forced aeration favored obtaining the highest titers of laccase (6.37 U/g ds) compared to natural convection and high aeration level. The greatest lignin degradation was also verified for low aeration regime. For the first time, pilot scale cultivation of T. versicolor was reported in a fixed-bed bioreactor.

On the Issue of Storing Seed Grain in a Vacuum Container

The article presents a fundamentally new technology for storing seed material in conditions typical for small and medium-sized farms. (Research purpose) The research purpose is in studying a container with a controlled air and gas environment in it. (Materials and methods) The article presents studies in order to obtain initial data for calculating the volume of the carbon dioxide storage tank using an original laboratory installation consisting of a sealed container with a vacuum gauge mounted on the lid. The process of seed respiration is characterized by the respiratory coefficient Kd, which is determined by the ratio of the volume of carbon dioxide released to the volume of oxygen absorbed in the air. (Results and discussion) During the aerobic respiration of seeds in the container, the composition of the air in the intergranular space is constantly changing, while the content of carbon dioxide increases and oxygen decreases. When determining the mass of the air medium, it is possible to obtain an expression that obeys the Mendeleev - Klayperon equation for an ideal gas for external climatic conditions, on the basis of which it is possible to calculate the mass content of carbon dioxide in the air mixture. (Conclusions) The article recommends the technology of storing seed grain in a sealed container with a controlled air environment and a system of forced aeration of the grain mass. It is necessary to create and maintain a vacuum of the air mixture in the working volume of the sealed container within 0.66 MPa. The forced aeration of the grain embankment should be started when the oxygen content in the air mixture located in the carbon dioxide storage tank exceeds 7 percent.

DEVELOPMENT OF THE TECHNOLOGY FOR BIOCONVERSION OF WASTE ACTIVATED SLUDGE FROM AN URBAN WASTEWATER TREATMENT PLANT

Pilot tests of the composting of waste activated sludge in an urban wastewater treatment plant with a consortium of thermophilic and thermotolerant bacteria has been carried out. The most effective was the bioconversion of activated sludge together with pine sawdust in a ratio of 1:1 or 1:2 using forced aeration of the mixture (0.35 m3/min).

Study of the Nutritional Increase in Organic Composts Obtained by Aerobic Biostabilization in the Management of Food Wastes

Composting is a sustainable alternative regarding an environmentally appropriate management of the organic fraction contained in the municipal solid wastes. To minimize nitrogen losses during the biostabilization process, due to ammonia volatilization, the present study aimed to evaluate the composting technique combined with the possible precipitation of struvite (MgNH4PO4.6H2O). A mixture containing food wastes was subjected to different experimental composting conditions with synthetic chemicals of magnesium and phosphorus—0.020 mol kg-1 (EXPI) and 1.8 mol kg-1 (EXPII), in addition to the control treatment (CONT). Experiments were carried out in closed systems, under forced aeration, over a period time of 56 days. In general, the addition of synthetic chemicals provided a nutritional increase in the organic composts obtained at the end of the experimental period in both conditions (EXPI and EXPII) compared to the treatment CONT. It was observed a total nitrogen conservation of about 21% and 122% in samples of composts obtained under the conditions EXPI and EXPII, respectively. Germination tests of lettuce seeds (Lactuca sativa) were also carried out to evaluate the agricultural applicability of the composts obtained in comparison with a commercial substrate (COM). A germination index with an average value of 87% was reached with the use of 100% of the compost obtained under the condition of greater conservation of total nitrogen (EXPII). Finally, the strategy considered for the conservation of nutrients in organic composts showed technical feasibility, indicating the formation of struvite and/or its analogues in the products obtained.