Water conservation in canned tuna (pet food) plant in Thailand

摘要

The common environmental problems of the fish industry in Thailand are high water consumption and high organic matter content in wastewater. Water consumption in canned tuna (pet food) processing is 13.0 m~3/ton of raw material, The major sources of wastewater are spray cooling process (4.7 m~3/ton) and equipment and floor washing (4.5 m~3/ton). The biggest pollution source in wastewater is from precooking, which has the COD, oil and grease, TS and SS of 66,222, 1,727, 57,192 and 7,000 mg/L, respectively. The combined wastewater has the COD, oil and grease, TS and SS of 3,248, 216, 3,799 and 742 mg/L, respectively. Water conservation measures were attempted at three processing steps. This included the installation of pressure spraying nozzles for spray cooling; the use of hot water (60 ℃) instead of cold water, and at reduced amount (opening the valve only 45 degrees) for can washing (after seaming); and educating the plant personnel on water conservation for equipment and floor washing. After the conservation measures were applied, water consumption at the three processing steps was reduced by 66, 55 and 14%, respectively. The net water consumption was 8.8 m~3/ton of raw material, representing a 32% reduction in overall water consumption.