Biogas Digesters for Swine Farms

What is the primary purpose of a covered lagoon biodigester?

What is one of the common problems faced by covered lagoon biodigesters?

What factor does the volume of a biodigester depend on?

Which construction technique helps prevent whaling in biodigesters?

How is the design operating volume of a biodigester determined?

What is the change in the maximum design VSLR when the temperature drops by 2 ºC?

Which design standard is critical for biodigester volume sizing?

What is the typical hydraulic retention time (HRT) for a swine farm biodigester at 32 ºC?

Covered Lagoon Biodigesters

A covered lagoon used to ferment diluted manure
Designed to reduce methane and carbon dioxide emissions
Utilized for biogas generation
Covered with geomembrane lining

Common Problems

Whaling: Build-up of biogas under the lining due to geomembrane leakage.
Prevention:
- Quality construction
- Underdrain system
- V-shaped bottom
- Gas venting system

Digester Volume Sizing

Based on Volatile Solids Loading Rate (VSLR) and Hydraulic Retention Time (HRT)
Minimum Operating Volume based on VSLR:
- Volume (m3) = VSLR (kg/day) / Maximum Design VSLR (kg/m3-day)
Minimum Operating Volume based on HRT:
- Volume (m3) = Influent Flow Rate (m3/day) x Minimum Design HRT (days)
Design Operating Volume: The larger value between VVSLR and VHRT

Digester Volume Design Information for Swine Farms in the Philippines

Maximum Design VSLR: ≈ 0.192 kg/m3-day at 32 ºC average
VSLR Change: ≈ -0.0025 kg/m3-day per 1 ºC drop in temperature
Volatile Solids: ≈ 0.1-1.04 kg/head-day, maximum for lactating sows
Hydraulic Retention Time (HRT): ≈ 35 days at 32 ºC average
HRT Change: ≈ +1 day per 2 ºC drop in temperature
Manure Volume: ≈ 0.001-0.01 m3/head-day, maximum for lactating sows
Water Inflow: ≈ 0.004-0.04 m3/head-day, maximum for lactating sows
Influent flow rate: Manure Volume/day + Water inflow/day
Maximum VSLR & Minimum HRT will determine digester volume

This quiz covers the design and operation of covered lagoon biodigesters specifically for swine farms. It delves into topics such as methane emission reduction, biogas generation, and critical volume sizing calculations. Test your knowledge on effective prevention strategies for common problems like whaling and learn about the key design parameters involved.