Abstract
Organic wastes of rural slaughterhouses in developing countries comprise of blood and undigested rumen contents harboring infectious microbial pathogens and having impermissible BOD5 and COD values. Previously we demonstrated valorization of blood and rumen contents through drying and conversion to an efficacious organic fertilizer which was free from infectious pathogens and heavy metals. Here we describe fabrication of a novel helical-ribbon mixer dryer for transition from the current small-scale household cooking to equipment-driven sustainable production. Blood and rumen digesta mixed in a 3:1 ratio, having initial moisture of 85%, were dried at 90–110 °C for 3–4 h to attain 15.6% final moisture-containing organic fertilizer. Energy consumption and moisture extraction rate were 49.4 MJ per batch and 18.9 kg h−1 respectively. Using this method, small abattoir owners could emerge as multi-product producers to enhance earnings while farmers could source the fertilizer locally for organic farming. The two activities can be complementary to each other and become a sustainable circular economy model. We applied a spreadsheet-based model for calculation of cash flow, breakeven point and conducted financial cost–benefit analysis on the projected operation of the dryer. Fertilizer production parallel with the meat trade should be profitable for slaughterhouse owners and farmers apart from generating local employment opportunities.
Highlights
Organic wastes generated in rural slaughterhouses of developing countries are discarded without any treatment due to desuetude of cost-effective recycling processes
The values of the measured parameters were beyond the permissible limits
Drying time and energy consumption were reasonably lower compared to the previous methods of bovine-blood-rumen digesta mixture” (BBRDM) preparation. (ii) As the conductive helical-spindle dryer presented in our work is portable, lacks in complicated attachments, and no sophisticated and expensive technologies are used, this dryer can be installed in scattered units of rural slaughterhouses. (iii) Considering the domestic and global demands for organic farming-based produce, small abattoir owners can emerge as multi-product producers to enhance net private earning
Summary
Organic wastes generated in rural slaughterhouses of developing countries are discarded without any treatment due to desuetude of cost-effective recycling processes. Landfilling is generally practiced for the disposal of slaughterhouse waste in developing countries because of the operative easiness and low management cost [1]. Beneficial microbial communities present in soil are negatively affected due to land application of raw organic waste [4]. Rural slaughterhouses receive all types of livestock, including diseased animals, because no screening for healthy/diseased is carried out. These abattoirs are the terminal station for disease-infected unproductive animals [5]. Several infectious pathogens are present in slaughterhouse waste that are capable of transmitting diseases to both humans
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