Vermicomposting process for treating animal slurry in Latin American rural areas

The management of animal slurry is a big issue in low-income rural areas worldwide. Bolivia suffers this issue related to collection, treatment and final disposal since the main solution applied is the open dumping. The aim of this study is to introduce a feasible treatment of animal slurry in the rural area of Carmen Pampa, where about 670 kg of dung are produced per day and disposed of in open areas. The objective is the improvement of the environmental sustainability and human health, providing an alternative solution for encouraging the circular economy. The study is focused on the vermicomposting process, a sustainable solution for low-income regions. The analysis was conducted in function of the earthworm breeds used locally ( Eisenia fetida and Lumbricus terrestris) and the application of activated bacteria (AB) for improving the process. The mass loss, the treatment time, and the growing rate of the earthworms were analyzed. The results suggest that the different breed of the worms allows gaining up to 19 days, while the use of the AB allows saving about 30 days. Moreover, the vermicomposting process reduced the mass of the slurry of about 65% for the swine’s dung and the bovine’s dung, and 90% of the hens’ dung. Finally, experimental evidence shows that the growing rate of the E. fetida is higher than the L. terrestris (F[1,8] = 78, p < 0.05), with an average of about 193%. The data obtained could be of interest for other stakeholders who live in similar environmental, climatic, and economic conditions for improving sustainability.

CORROSION EFFECT OF ANIMAL SLURRY ON LOW CARBON S235JR STEEL AT 333 K

Low-carbon steels are often used for materials in the construction of machines and equipment for agricultural. One of the most important factors constructional material is corrosion resistance, first of all in demanding animal environment. Equipment with low carbon steel can be easy join by quickly welding at a low construction price, but one with the serious problem in aggressive environment is their corrosion resistance. A few corrosion processes in crevices and awkward corners can be avoided at the design stage (low roughness parameters, round-section and other). But still the construction material is exposed to corrosion. Slurry is a mixture of dung and urine. The aggressive corrosive constituents in slurry are urea, uric acid, naturally excreted chloride and as well as ammonia or ammonium salts. The main aim of this research is to investigate corrosion resistance in different time (48, 96, 144, 192, 240, 288, 336 hours). For this used weight loss of test samples and its profile roughness. The research was conducted on low carbon steel in grade S235JR in natural animal slurry at 333 K. Corrosion tests confirmed that the research this steel in animal slurry as corrosive environments is characterized through proportionate to time corrosion process whose measure may be surface roughness. In industrial practice roughness parameters for all the research times can be used for determine the stage and size of steel corrosion.