2.1. Grass silage preparation and reactor design
Pig manure and pig form waste water was obtained from a pig
farm ‘‘the sacred pig farm and Sons Farms Ltd’’ in Chiang Mai, Mae
Taeng district, Thailand. The farm has 35,000 pigs; those pigs were
produce fresh active substrate of about 10–12 tons per day mixed
with the effluent a day and the farm size is about 300 m3
. Elephant
grass was collected from the agriculture form which was cultivated
around Mae Taeng district, Thailand. The Elephant grass silage
(grass silage) was used about 20–23 tons per day which was grown
at 45 days period. The grass silage particle size was 1.0 mm.
In this study performed with continuously stirred tank reactors
(CSTRs) and triplicate production units (i.e. CSTR1, CSTR2, and
CSTR3) were used; each unit having a working capacity of
1700 m3 per tank and a volume control for consistent feed. The
CSTRs were placed on a three-position stirrer hotplate system.