Adsorption properties of natural zeolite and bentonite in pig slurry from the microbiological point of view

Veterinarni Medicina 44, 1999, 339-344

Zeolites and bentonites are natural sorbents which, due to their adsorption properties and high affinity to ammonium ions, are capable of removing ammonium and undesirable odours from the environment and, because of that, can appear beneficial in the treatment of pig excrements. In our experiments we studied the influence of zeolite and bentonite on physical-chemical and microbiological parameters of pig slurry. After 28 days of contact of pig slurry either with zeolite or with bentonite, the plate counts of psychrophilic and mesophilic microorganisms decreased by 3 orders of magnitude in comparison with the control. The efficiency of removal of psychrophilic and mesophilic microorganisms was 98.9% and 100%, respectively. Coliform microorganisms were not detected after 14 days of the treatment of slurry either with zeolite or with bentonite. No fecal coliform microorganisms were detected in bentonite-created slurry after 7 days of contact and in zeolite-treated slurry after 14 days of contact. During the experiment a decrease in the concentration of ammonium nitrogen (N-NH4+), total nitrogen (N-t), total phosphorus (P-t) and chemical oxygen demand (COD) was observed. The decrease in comparison with the control was significant for N-NH4+ (P < 0.05), N-t (P < 0.05), Pt (P < 0.05). The effectiveness of removal expressed in per cent was 59.2% for zeolite and 60.2% for bentonite, Both sorbents contributed to better sedimentation of suspended particles and decrease in odour. The results point to the possibility of utilization of zeolite and bentonite in the initial stages of pig excrement treatment

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