Assessment of heavy metals accumulation by vegetables irrigated with different stages of textile wastewater for evaluation of food and health risk.

Wastewater irrigation for vegetable cultivation is greatly concerned about the presence of toxic metals in irrigated soil and vegetables which causes possible threats to human health. This study aimed to ascertain the accumulation of heavy metals (HMs) in edible parts of vegetables irrigated with different stages of textile dyeing wastewater (TDW). Bio-concentration factor (BCF), Estimated daily intake (EDI), and target hazard quotient (THQ) were computed to estimate human health risks and speculate the hazard index (HI) of adults and children with the consumption of HMs contaminated vegetables at recommended doses. Five vegetables (red amaranth, Indian spinach, cauliflower, tomato, and radish) in a pot experiment were irrigated with groundwater (T1) and seven stages of TDW (T2∼T8) following a randomized complete block design (RCBD) with three replications. Among the TDW stages, T8, T7, T4, and T5 exhibited elevated BCF, EDI, THQ, and HI due to a rising trend in the accumulation of Pb, Cd, Cr, and Ni heavy metals in the edible portion of the red amaranth, followed by radish, Indian spinach, cauliflower, and tomato. The general patterns of heavy metal (HM) accumulation, regarded as vital nutrients for plants, were detected in the following sequence: Zn > Mn/Cu > Fe. Conversely, toxic metals were found to be Cd/Cr > Ni > Pb, regardless of the type of vegetables. Principal Component Analysis (PCA) identified T8, T7, and T4 of TDW as the primary contributors to the accumulation of heavy metals in the vegetables examined. Furthermore, the analysis of the heavy metals revealed that the BCF, THQ, and HI values for all studied metals were below 1, except for Pb. This suggests that the present consumption rates of different leafy and non-leafy vegetables, whether consumed individually or together, provide a low risk in terms of heavy metal exposure. Nevertheless, the consumption of T8, T7, and T4 irrigated vegetables, specifically Indian spinach alone or in combination with red amaranth and radish, by both adults and children, at the recommended rate, was found to pose potential health risks. On the other hand, T2, T3, and T6 irrigated vegetables were deemed safe for consumption. These findings indicated that the practice of irrigating the vegetables with T8, T7, and T4 stages of TDW has resulted in a significant buildup of heavy metals in the soils and edible parts of vegetables which are posing health risks to adults and children. Hence, it is imperative to discharge the T8, T7, and T4 stages of TDW after ETP to prevent the contamination of vegetables and mitigate potential health risks.

Optimizing textile dyeing wastewater for tomato irrigation through physiochemical, plant nutrient uses and pollution load index of irrigated soil.

Reuse of wastewater for vegetable cultivation is becoming popular in order to augment the inadequate irrigation supplies and meet the growing demands of ground water for agriculture and industries production in different regions of the world. This study was investigated to optimize different stages of textile dyeing wastewater (TDW) for irrigation focusing on their effect on growth, yield and physiochemical attributes of tomato, plant nutrient use, heavy metals enrichment and pollution load of the irrigated soil. Textile wastewater were collected from the seven stages of (second wash after scouring and bleaching T2; enzyme treated water T3; second wash after bath drain T4; neutralization treatment T5; second wash after soaping T6; fixing treatment water T7; mixed effluent T8) of a dyeing process for physiochemical characterization and evaluation their irrigation feasibility for tomato cultivation in compare with the ground water (T1). The pot experiment consists of eight irrigation treatments was laid out following a completely randomized block design with three replications. Results showed the presence of plant nutrients and heavy metals in all the studied samples where T8 (mixed effluent) exceeded the limit of agricultural standard for almost all physiological parameters such as TDS, TSS, EC, BOD, COD affording the highest value. T8 also delivered the highest Cl- and heavy metals like Cd, Ni, Cr followed by T4 < T7. As a consequence, these provided comparatively higher enrichment factor (EF), pollution load index (PLI) and sodium absorption ratio (SAR) to transform fresh soil into the category of severe and slightly to moderate saline. Therefore, the yield and physiochemical attributes of tomato were dramatically reduced with T8 and T4 treatment. On the other hand, T2, T3 and T6 treatment had significant positive impact on growth and yield of tomato due to having higher N, P, K, S and lower heavy metals (Cu, Zn, Fe, Pb, Cd, Ni, Cr) than the recommended guideline. These features were contributed to cause minimum EF and PLI in the soil irrigated with T2, T3 and T6 stages of TDW. Correlation matrix demonstrated that EF and PLI of heavy metals (except Cd, Ni) were negatively related to yield, while positively related to SAR and fruit abortion. Although T6 (2nd wash after soaping) performed better in respect to growth, yield, yield attributes and nutrient use efficiency, principal component analysis revealed that T2 (2nd wash after scouring and bleaching) and T3 (enzyme treated water) were also belong to the same group of T6 and T1 (ground water). Thus, it may be suggested that T2, T3 and T6 stages of textile dyeing wastewater could be used profitably without ETP for vegetable cultivation and would effectively supplement not only the nutrient requirement of the crop but may also act as the alternate source of irrigation water. Although, further research is needed to sort out the health risk assessment through the heavy metals' accumulation in the plant parts after irrigation with different stages of textile dyeing wastewater.