Comparison of metal lability in air-dried and fresh dewatered drinking water treatment residuals

Abstract

In this work, the labilities of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in air-dried (for 60 days) and fresh dewatered WTRs were compared using the Toxicity Characteristic Leaching Procedure (TCLP), fractionation, in vitro digestion and a plant enrichment test. The results showed that the air-dried and fresh dewatered WTRs had different properties, e.g., organic matter composition and available nutrients. The air-dried and fresh dewatered WTRs were non-haf zardous according to the TCLP assessment method used in the United States; however, the metals in the two types of WTRs had different lability. Compared with the metals in the fresh dewatered WTRs, those in the air-dried WTRs tended to be in more stable fractions and also exhibited lower bioaccessibility and bioavailability. Therefore, air-drying can decrease the metal lability and thereby reduce the potential metal pollution risk of WTRs.

The Physiological and Biochemical Responses of Daphnia magna to Dewatered Drinking Water Treatment Residue

“…On the other hand, the relatively high stability of heavy metals in dewatered DWTR could be related to the treatment of air-drying to fresh dewatered DWTR, which has been demonstrated in a previous study [ 45 ]. The fresh dewatered DWTR was often block shaped in irregular form and with relatively high moisture contents.…”