ENVIRONMENTAL IMPACT FROM WASTEWATER EFFLUENT OF THE SILK COTTAGE INDUSTRY: A CASE STUDY OF PAK THOHG CHAI, NAKHON RATCHASIMA, THAILAND

摘要

The study was conducted at Pak Thong Chai district in Nakhon Ratchasima Province, where high quality Thai silk is produced. Extensive chemical substances, dyes and water are used during bleaching and dyeing process. Effluents were released directly onto the ground or into canal that affect the local environment and national resources in these areas. The aims of study were to determine the wastewater characteristics; pH, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Dissolved Solids (TDS) from bleaching and dyeing process and to investigate the contamination of lead (Pb) and Cadmium (Cd) in water .sediments and soil nearby silk cottage industry. According to the Thai industrial effluent standard, all samples of wastewater had high pH value but not exceed the standard (5.5-9). The determination of the BOD, COD and TDS were 338 - 2,483, 480 -1,325 and 437.64 - 628.73 mg/L, respectively that higher than the level allowed by the national standard. The contamination of Pb and Cd in water resources were 5.722 - 15.024 and 0.285 - 0.834 ppb, respectively, whereas Pb and Cd in sediments were 158.47-262.26 and 2.46-4.13 ppb, respectively The contamination of Pb and Cd in soil nearby silk production areas were 19.36 - 33.03 and 0.02 - 0.34 ppm, respectively. The sample site that polluted by effluent had Pb and Cd concentration higher than another area. It was found from the field observation that all sample sites were untreated effluent and overflowed to the land, even though some have small onsite treatment. Therefore, implementation of the appropriate wastewater system should be promoted to silk cottage industry.