The study of effluent quality from indigo dyeing process: A case study of the indigo dyeing community enterprise, Sakon Nakhon province

Abstract

The natural indigo-dyed fabric is a renowned and highly popular product under the One Tambon One Product (OTOP) initiative of Sakon Nakhon Province. In the production of indigo-dyed fabric, yarns are dyed with indigo pigment and then washed to remove excess dye. This washing stage results in the generation of wastewater in the indigo dyeing process. This research was a survey study aimed at investigating the wastewater quality from the indigo dyeing process compared with the announcement of the Ministry of Natural Resources and Environment on the determination of standards for controlling wastewater discharge from small businesses that produce certain types of goods or services, 2021. Wastewater samples were collected from community enterprises engaged in indigo dyeing in Sakon Nakhon Province, covering 8 districts, with a total of 40 samples. The study found that the average dissolved oxygen (DO) concentration was 2.51±1.68 mg/l, pH 8.84±1.15, electrical conductivity (EC) 1019.63±1088.81 µS/cm, and color 1732.29±2338.41 PCU. The biochemical oxygen demand (BOD) was 2.04±1.58 mg/l, chemical oxygen demand (COD) 397.20±633.42 mg/l, total solids (TS) 1442.33±1831.84 mg/l, total suspended solids (TSS) 535.15±941.82 mg/l, and total dissolved solids (TDS) 931.05±1171.85 mg/l. The settable solids were 3.98±8.03 mg/l, total nitrogen (TN) 5.10±8.62 mg/l, total phosphorus (TP) 0.30±0.22 mg/l, and organic matter content was 238.03±337.92 mg/l. The color value, COD, TSS, and settable solids values exceeded the permissible limits when compared to Thailand's wastewater discharge standard.