Nitrification of swine waste

Area of Science:

• Environmental Microbiology
• Wastewater Treatment
• Biogeochemical Cycles

Background:

• Swine waste contains significant ammonia nitrogen, posing environmental challenges.
• Nitrification, the oxidation of ammonia to nitrate, is crucial for nitrogen removal in wastewater.
• Stabilized swine waste has low populations of nitrifying bacteria (nitrosobacteria and nitrobacteria).

Purpose of the Study:

• To investigate methods for accelerating ammonia oxidation in stabilized swine waste.
• To determine the effectiveness of activated sludge and calcium carbonate addition for nitrification.
• To evaluate the impact of enriched nitrifying populations on nitrification efficiency.

Main Methods:

• Incubation of stabilized swine waste with activated sludge and calcium carbonate at controlled temperature and agitation.
• Monitoring ammonia, nitrite, and nitrate concentrations over time.
• Quantifying nitrosobacteria and nitrobacteria populations using most probable number (MPN) method.

Main Results:

• Complete ammonia oxidation to nitrite in stabilized swine waste required 49 days without amendments.
• Addition of 10% activated sludge and 1.5% CaCO3 significantly accelerated ammonia oxidation to nitrite within 5 days.
• Inoculation with enriched nitrifying populations (10^6-10^7 MPN/mL) and CaCO3 resulted in complete nitrification (ammonia to nitrate) in 5-10 days without nitrite accumulation.

Conclusions:

• Activated sludge and calcium carbonate are effective amendments for enhancing nitrification in swine waste.
• Enriched nitrifying bacterial inocula can dramatically reduce the time required for complete nitrogen removal.
• Optimized conditions enable rapid and efficient nitrification of swine waste, mitigating environmental pollution.