Effect of sodium hypochlorite on the microbiota and odor of manure effluents

Abstract

Manure effluents (ME) of livestock enterprises represent a rich nutrient medium for the development of various aerobic microorganisms (MO). During the biodegradation of the organic components of ME, a wide range of odor-forming substances (OFS) and greenhouse gases enter the atmospheric air. The intensity and main directions of ME destruction depend on the composition and amount of microbiota. A solution of sodium hypochlorite can be used to suppress the decomposition of the biogenic components of ME. In the course of our research, it was found that the introduction of 0.005% active chlorine into the liquid fraction of ME (pH ~ 6.8; humidity ~ 99.1%) leads to a decrease in the numbers of putrefactive microbiota, namely: Bacteroides, Clostridium, Escherichia coli, Pseudomonas, Sarcina ventriculi, and Peptostreptococcus anaerobius. The corresponding ammonifiers are actively involved in the biodegradation processes of organic substances to form acetic acid, isovaleric acid, butyric acid, indoles, skatoles, ammonia, hydrogen sulfide, mercaptans and others. The numbers of microbiota not making a significant contribution to the production of OFS (Saccharomyces cerevisiae, Rhodotorula glutinis, Lactobacillus ssp. and others), on the contrary, increased. The numbers of some producers of volatile fatty acids (VFA), namely: Anaerococcus prevotii, Acidaminococcus, Prevotella spp. etc. increased. However, this did not affect the intensity and nature of the ME odor, which can be explained by the formation of non-volatile VFA salts at pH above 7.0. The numbers of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella sp., Proteus ssp., Alistipes putredinis, Bifidobacterium ssp., Candida tropicalis, and Candida albicans almost did not change when NaOCl was added to ME. As a result of the microbiota transformation, the total emission of gaseous substances, whose main components are the greenhouse gases CO2 and CH4, decreased by more than 17%. The unpleasant odor intensity has significantly decreased. A NaOCl solution can be used to treat ME in manure storage baths. The introduction of the practice of treating ME with this biocide is facilitated by its availability, low cost and safety for the environment.