Correlating plant-to-pollutant mass ratio in phytotreating batik industry effluent using Actinoscirpus grossus

Batik, a clothing fabric, is synonymous with people in Southeast Asian countries. The batik industry is one of the industries that produces poorly treated wastewater. This study was conducted to determine the capability and suitability of phytoremediation treatment using Malaysia’s native plant, Actinoscirpus grossus (previously known as Scirpus grossus ) , with plant-to-pollutant ratio (PPR: g plant/g COD) approach. Four A. grossus plants (40.4±4 g) were exposed to batik effluent with four different COD concentrations (275 mg/L for 40% dilution, 399 mg/L for 60% dilution, 484 mg/L for 80% dilution and 637 mg/L for batik effluent without dilution) for 28 days. The PPR of batik industry effluent concentrations of 40%, 60%, 80% and 100% was calculated and denoted as PPR1 (49 g plant/g COD), PPR2 (33 g plant/g COD), PPR3 (27 g plant/g COD) and PPR4 (21 g plant/g COD), respectively. Physical appearance, length, COD and colour removal efficiencies were monitored throughout the 28-day exposure period. Results showed that the plant ratio of PPR2 and the exposure of 28 days with 77.2% COD removal were sufficient to be used for phytoremediation of similar effluents. The total mass of plants required for a future system can be estimated based on the PPR approach. This approach could ease the reproducibility of the treatment for similar types of wastewaters and for scaling up for real industry applications. • High pollutant mass leads to high toxicity towards plants and low removal efficiency. • Plant-to-pollutant mass ratio (PPR: g plant / g COD) plays an important tool in phytotreatment. • High plant-to-pollutant mass ratio (PPR) leads to high pollutant removal rate and plant survival. • Plant survival was high for a PPR of 33 g plant /g COD. • PPR can be correlated to the scale-up process of phytotreatment.