Leachability of endocrine disrupting chemicals (EDCs) in municipal sewage sludge: Effects of EDCs interaction with dissolved organic matter.

In this study, experiments were performed to assess the significance of dissolved organic matter (DOM) on the leachability of four common EDCs, i.e., bisphenol A (BPA), 17α-ethinylestradiol (EE2), progesterone (PGT) and testosterone (TST), in municipal sewage sludge (MSS) under landfill conditions. The DOM was derived from two sources: MSS (MDOM), and natural soil represented by organic matter obtained from the Suwannee River (NDOM). Fluorescence excitation-emission matrix quenching combined with parallel factor analysis was adopted to characterize the interaction properties between the EDCs and DOM. The accumulative leachability of the target EDCs ranged from 0.09% (PGT) to 3.8% (TST). In particular, the leaching of BPA, EE2 and TST followed S-shaped curves, while PGT exhibited continuous leaching potential in untreated MSS. With the introduction of DOM, (i) the leachability of BPA and EE2 increased to 13.4% and 61.6%, respectively, whereas those of PGT and TST declined by 61.3% and 45.8%, respectively, and (ii) BPA, EE2 and PGT no longer reached leaching equilibrium but the S-shaped leaching property of TST persisted. The differential effects of MDOM and NDOM at identical concentrations on the EDCs leachability increased with curing time. BPA, EE2 and PGT quenched the MDOM fluorophores attributed to aromatic protein-like components. The fluorescence quenching of NDOM by BPA, EE2 and PGT was centered on soluble microbial by-product-like and humic-like substances. Compared with PGT, EE2 and BPA had greater capability for binding with DOM components largely via hydrophobic interactions, whereas PGT preferentially interacted with the DOM hydrophilic functionalities through specific interactions. TST had no binding capability but displayed potentials competing for sorption sites with DOM moieties. Our findings suggested that the management of MSS increased the risk of environmental contamination by EDCs for a long duration and that DOM was a useful indicator to predict the migration and transport properties of EDCs.

Amendment of municipal sewage sludge with lime and mussel shell: Effects on fate of organic matter and pharmaceutically active compounds.

The deterioration in its strength from long-term degradation of organic matter and release of pharmaceutically active compounds (PhACs) have caused adverse environmental effects in municipal sewage sludge (MSS) landfill. Lime and a mixture of lime and mussel shell were employed as potential stabilization agents for MSS in this work. Their efficacy was assessed by investigating the effects on transformation of organic matter, as well as the occurrence and fate of four PhACs (fluoxetine, gemfibrozil, triclosan and carbamazepine) over 42 days. The addition of the selected agents: (i) prevented the microbial degradation of organic matter; (ii) modified the predominant functional groups of amide groups (amide I and II) and polysaccharides to deprotonated carboxylic groups and destruction of amide groups; and (iii) shifted the abundance of organic constituents from microbial by-products to humic acid-like organics with conformational changes. The measurement method provided reliable and precise results for determining PhAC concentrations in MSS with and without amendment, although matrix effects and process effects were found to affect measurement sensitivity. Available fractions of the PhACs increased in MSS with lime addition, but decreased in the presence of the mixture of lime and mussel shell due to the strong adsorption effects of the shells. The mixture of lime and mussel shell would be recommended for stabilizing MSS prior to being landfilled. However, longer term and larger scale investigation may be needed to better evaluate the applicability of lime and mussel shell for reducing the hazards and facilitating the management of MSS.

Mobility of pharmaceutical and personal care products in lime amended wastewater biosolids.

Lime amendment of biosolids can produce large quantities of hydroxyl ions and increase biosolids pH. The mobility of some pharmaceutical and personal care products (PPCPs) is closely correlated with the pH of biosolids. In this study the mobility of six PPCPs: erythromycin, fluoxetine, carbamazepine, naproxen, gemfibrozil and triclosan, was measured in unamended and lime-amended biosolids over 63days. Biosolids were equilibrated either a at pH range of 5.5-11.5 or cured over a time period up to 63days. The mobility was calculated as the proportion of PPCPs associated with the soluble phase after a given equilibrium time or a curing period. In unamended biosolids the mobility of erythromycin, fluoxetine, gemfibrozil and triclosan decreased, the mobility of naproxen increased and the mobility of carbamazepine was almost unchanged over 63days of curing. Compared to unamended biosolids, lime addition increased the mobility of erythromycin and naproxen by 21.7% and 33.8% respectively, but suppressed the mobility of carbamazepine, fluoxetine, gemfibrozil and triclosan by up to 100% after 63days. The pH influence on hydrophobicity and speciation of PPCPs correlated well with the mobility of erythromycin and fluoxetine, but only partially correlated with the mobility of the other 4 compounds over the pH of 5.5-11.5. Attenuated total reflectance Fourier transformed infrared (ATR-FTIR) and emission-excitation matrices (EEMs) provided spectroscopic evidences showing that the increases in amide and carboxylic groups, the decrease in polysaccharides, and the increases in humic substances in dissolved organic matter (DOM) may be responsible for the changes in the PPCPs' mobility. The effects of lime amendment lasted for approximately a month. The results of this work suggest that lime amendment prevents some PPCPs from being dissolved in biosolids soluble phases, but may not "lock" all PPCPs into biosolids.

Amendment of biosolids with waste materials and lime: Effect on geoenvironmental properties and leachate production.

Residuals from wastewater treatment operations (biosolids) were mixed with lime, fly ash, lime kiln dust, or two smelter slags to assess their efficacy as potential stabilisation agents by assessing their effects on the shear strength, compressibility, and solids content of mixtures. In addition, the minerals formed and leachate produced during stabilisation were determined. Tests were performed to explore the change of the geoenvironmental properties of the amended biosolids, while under pressure, at different scales using laboratory, pilot and field scale tests. The settlement characteristics of the amended biosolids under a range of applied pressures were determined using a consolidometer. All amended biosolids mixtures showed higher strength than the unamended biosolids, with mixtures containing a combination of 20% fly ash and 20% lime giving the highest (up to eightfold) increase in strength, and that with lime kiln dust and the smelter slags showing the lowest (up to twofold). The biosolids mixtures with only lime gave the second highest increase in strength (up to fourfold), but produced the largest amount of leachate, with higher level of dissolved calcium. The increase in strength correlated with availability of calcium oxide in the mixtures which lead to calcium carbonate formation, accompanied with higher leachate production and settlement during consolidation. Copper, nickel and zinc concentrations increased with alkaline additives and corresponded to higher pH and DOC levels. Nonetheless, concentrations were within the New Zealand regulatory limits for Class A landfills.