Municipal Solid Waste (MSW) contains a relatively large amount of organic matter, which decomposes by the actions of microorganisms under anaerobic conditions to produce biogas. The total solids (TS) concentration of the waste influences the pH, temperature and effectiveness of the microorganisms in the decomposition process. This work investigated various concentrations of the TS of MSW in an anaerobic continuously stirred tank reactor (CSTR) and the corresponding amounts of biogas produced, in order to determine conditions for optimum gas production. Five laboratory-scale anaerobic batch digesters of 5 litres volume each were set up for the digestion of 2kg of shredded MSW diluted to a %TS concentration of 26.7%. The results from the batch experimentation were adapted to the design of a CSTR for the digestion of MSW. The CSTR was simulated over a range of %TS concentration of 4-10, at a maximum fractional conversion of 0.8 to cater for system inefficiencies. Mathematical models were developed for the process and solved using the Microsoft Visual Basic version 6.0 Programme. The results show the amount of biogas produced as a power function of the %TS concentration, indicating that as the process continues, a time comes when any marginal increase in the %TS concentration would no longer contribute to the increasing volume of biogas produced. The results further show that, given the limiting upper boundary of the %TS concentration, optimum biogas production in a CSTR digesting MSW cannot be ascertained with the concentration of the %TS alone.
A bulk quantity of bambara groundnut pods (milk coloured) was purchased from a local farmer in Damboa, Borno State, Nigeria. The pods were prepared for experiment by cleaning and varying their moisture content to have three different moisture levels (5.3, 9.6 and 12.2% db). Three groups of impellers (forward facing, radially positioned and backward facing) each group with three different number of slots (eight slots, four slots and two slots) were used for the shelling of the pods. One hundred pods were randomly selected from each pod sample and introduced into the centrifugal cracker. This was replicated five times for each impeller at the three moisture levels. Results of the tests carried out were examined using 3x3x3 factorial design with moisture content, number of impeller slots and impeller slot angulations as variables. Results showed that the forward facing impeller with eight numbers of slots gave 96% effective shelling efficiency, 3.4% breakage and 0.6% partially shelled pods at an average feed rate of 215.8 kg/h, and impeller speed of 1900 rpm.
Evaluation of the performance of wet land weeders is inevitable as weed infestation is one of the limiting factors in the rice cultivation in India. The advent of mechanical rice transplanter to Indian agriculture encouraged farmers to use inter-row weeding tools like Rotary weeder, Cono weeder etc. These instruments are now popularising among farmers instead of tedious and low productive hand weeding. The main objective of this study was to evaluate these weeding tools quantitatively and qualitatively in terms weeding performance, economic aspects, ergonomic effectiveness, subjective judgement of Work Related Body Discomfort (WRBD) and work performance in comparison with hand weeding and the study was conducted in Malappuram district of Kerala State, India. In addition, different weed management practices viz. hand weeding, Rotary weeding + one hand weeding, Cono weeding + one hand weeding, Rotary weeding alone, Cono weeding alone, were conducted in the study area to assess the effect of different weeding methods on crop growth and yield with the help of statistical analysis. Ergonomic results showed that the energy requirements for the male subject group corresponding to rotary weeding, cono weeding and hand weeding were respectively 26.5, 24.0 and 16.0 kJ/ min. For the Female subjects, the corresponding values were 18.0, 15.0 and 9.5 kJ/ min respectively. The Field Performance Analysis in 15 experimental plots at the study area showed the weeding efficiency as 79 % and 72.5 % respectively for Rotary weeder compared to Cono weeder with damage factor of 7.06% and 4.55% respectively. The ANOVA based statistical analysis shown that weeding operation has significant influences on crop growth and yield parameters.
Anthropometric data of agricultural workers is very essential for the safe and efficient design of farm machinery. The anthropometric data of about 2000 male and female agricultural workers was collected throughout the state of West Bengal, India. For making the data comprehensive and more useful, a set of 21 body dimensions, which are found to be relevant in the design of various machines were selected. The data was analyzed and the application of several important parameters have been done for the design of agricultural equipment.
Leaf handling in the first stage of black tea manufacture, viz. withering (dehydration of leaf up to a desired level), is heavily manual labour intensive, although the subsequent stages, viz. leaf-cell distortion, polyphenol oxidation (fermentation), and drying or firing; and also postmanufacturing operational phases sorting and grading, as well as packing, have long been mechanized and made continuous in sequence of operations through conveyor connectivity. Manual handling of tea leaf for withering is not only labour intensive, but also causes damage to fresh tea leaf and degradation to made tea quality. If tea leaf handling in withering were mechanized it could reduce fresh leaf damage and retain or improve made tea quality. With a view to mechanize the leaf handling operations involved in trough withering system, a conceptual functional design of a mechanical system was hypothesized and accordingly a physical working model of the system was developed, which was found to be quite effective in doing its intended functions, i.e., spreading of fresh tea leaf uniformly over the trough bed;, unloading of withered tea leaf from the trough bed; and shifting of the same up to a leaf distorting machine (eg, a rotorvane) for next-stage operation(s). The system, which was developed primarily for a single withering trough, could be easily extended to a number of withering troughs to form a unified mechanical loading-unloading cum withered-leaf shifting system for several withering troughs for industrial application. The present paper provides concept and physical descriptions as well as performance of the mechanical system.
The objective of this research was to detect and recognize the plant stress caused by disease in the field conditions by combining hyperspectral reflection information between 450 and 900nm and fluorescence imaging. The results can be used to develop a tractor mounted cost-effective optical device for site-specific pesticide application in order to reduce and optimize pesticide use. The work reported here used yellow rust (Puccinia striiformis) disease of winter wheat as a model system. In the field hyperspectral reflection images of healthy and infected plants were taken by an imaging spectrograph mounted at spray boom height. Leaf recognition and spectral normalization procedures were used to account for differences in canopy architecture and spectral illumination were used. A model, based on quadratic discrimination, was built, using a selected group of wavebands to differentiate diseased from healthy plants. The model could discriminate diseased from healthy crop with an error of about 10% using measurements from only three wavebands. Multispectral fluorescence images were taken on the same plants using UV-blue excitation. Through comparison of the 550 and 690 nm fluorescence images, the detection of disease was clearly possible. Fraction of pixels in one image, recognized as diseased, was set as final fluorescence disease variable and called the lesion index (LI). The lesion index was added to the pool of normalized selected reflection wavebands. This pool of observations was used in a quadratic discrimination model. The combined model improved disease discrimination compared to either the spectral model or fluorescent model and had a classification error of between 5 and 6 %. The results suggest that there is a potential for developing detection systems based on multisensor measurements that can be used in precision disease control systems for use in arable crops.
A study on monitoring of nitrogen (N) leaching was conducted in acid- sulfate clayey soil in the central region of Thailand. The objective was to measure the N leaching to shallow groundwater from a tropical paddy field to assess the consequences of agricultural management practices. Mass balance approach was used to estimate the contribution of nitrogen fertilizer to the water environment. The N inputs to and outputs from field were measured by direct method. Inputs of N to the site came from commercial fertilizer, precipitation, irrigation water and soils. Outputs of N from the site were leached to groundwater, harvested crops, in surface runoff, soils and loss from the field. Leaching loss was calculated from daily fluxes of water percolation and soil water N concentrations extracted by vacuum lysimeter. Based on three month observation, average leaching of nitrate nitrogen (NO- 3-N), ammonium nitrogen (NH4 +-N) and total Kjeldahl nitrogen (TKN) to groundwater was found 0.04, 0.11 and 0.17 kg ha-1d-1 respectively. It was also observed that fertilizer application increased NO- 3-N concentration at five-fold in groundwater. Although, the measured NO- 3-N concentration in groundwater was below the threshold value of WHO drinking water standard (10 mg/l), such increment may pose a serious threat during the dry season when the groundwater recharge is very low. Furthermore, nitrogen mass balance result showed that loss of N inputs as outflow to the water and atmosphere were from the 19 % and 13.6% of total applied N respectively which indicates fertilizer input was responsible for water pollution. In this study, minor components such as groundwater input, mineralization and input from the atmosphere through biological fixation were ignored due to lack of available data where it should be considered.
A concept of a system has been prepared for obtaining hot water from the so-called hybrid wall (i.e. outer wall with build-in piping system, covered with transparent thermal insulation) integrated into living quarters or a livestock building structure. With the help of a special computer programme, a number of simulation calculations have been conducted of the system operating in a natural environment, and the calculated results have been compared with the experimental data. The impact of specific system parameters has been described, as well as the wall surface and construction, pipe spacing, water tank capacity and the yield of the water pump on passive and active solar heat gain. Results of the calculations showed that it was possible to optimise the hybrid wall through calculation.
