Combination of H2SO4-acidification and temperature-decrease for eco-friendly storage of pig slurry | JoVE Visualize

Area of Science:

Environmental Science
Agricultural Engineering
Biogeochemistry

Background:

Sulfuric acid (H2SO4) acidification is a common method to reduce methane (CH4) emissions from pig slurry (PS) storage due to its economic benefits.
However, H2SO4 acidification presents safety concerns and leads to hydrogen sulfide (H2S) emissions, necessitating a reduction in the required H2SO4 amount.
Low-temperature storage is explored as a strategy to potentially mitigate these issues.

Purpose of the Study:

To investigate the combined effect of mild H2SO4 acidification and low-temperature storage on reducing CH4 emissions from pig slurry.
To determine the optimal conditions for minimizing H2SO4 usage while achieving significant greenhouse gas (GHG) reduction.
To assess the impact of these combined treatments on methanogen abundance and activity.

Main Methods:

Pig slurry was subjected to mild acidification (pH 6.5 and 7.0) and stored at reduced temperatures (20-35°C).
Methane (CH4) emissions were quantified and compared to a control group (non-acidified, 35°C).
Methanogen abundance and specific methanogenic activity were analyzed to understand microbial community shifts.

Main Results:

CH4 emissions were reduced from 55.1 kg CO2 eq./ton PS (control) to 14.4-40.2 kg CO2 eq./ton PS at 20-30°C.
Decreasing temperature increased the abundance of low-temperature-tolerant methanogens but decreased overall specific methanogenic activity.
Achieving 70% CH4 reduction required only 0.5 kg H2SO4/ton PS at 25°C, compared to 1.6 kg H2SO4/ton PS at 35°C.
Combined treatment resulted in a 21-33% increase in CH4 production potential compared to the control, indicating effective GHG mitigation.
A GHG reduction of 33.6-41.9 kg CO2 eq./ton PS and a profit of 6.6 USD/ton PS were achieved.

Conclusions:

Combining mild H2SO4 acidification with low-temperature storage is an effective strategy for significantly reducing CH4 emissions from pig slurry.
This integrated approach lowers the required amount of H2SO4, addressing safety and H2S emission concerns.
The findings highlight the potential for cost-effective and environmentally sound manure management through optimized storage conditions.