We evaluated greenhouse gases (GHGs) emissions from an open-type anaerobic system (OAS) treating
ribbed smoked sheets (RSS) wastewater in a processing factory. The emitted biogas comprised 57.7%
e60.8% methane, 14.5%e31.5% carbon dioxide, 10.8%e24.7% nitrogen, and 329e423 ppm of nitrous oxide.
In the OAS, the chemical oxygen demand (COD) degraded as the methane emission rate increased from
influent to effluent. Finally, 94.4% of the total COD was removed. More than 90% of the removed COD
converted to methane. Methane emitted from the bottom and the wall surface of the OAS. Methaneproducing
bacteria was detected by a cloning analysis of the 16S rRNA gene. The predominant species
differed depending on the degradation characteristics of the RSS wastewater in the OAS. The emission
rate of methane and nitrous oxide ranged between 2.58 and 8.85 NL/(m2 hr) and between 0.074 and
0.410 NL/(m2/hr), respectively. Moreover, 0.153 t-CO2eq of GHGs were emitted from 1 m3 of RSS
wastewater treatment. Nitrous oxide accounted for 65% of the total GHGs emissions because of its high
global warming potential. Therefore, both nitrous oxide and methane that emitted from the treatment of
wastewater from a natural rubber processing factory must be considered as significant contributors to
the GHGs.