Evaluation of the co-application of fly ash and sewage sludge on soil biological and biochemical quality

Abstract

Disposal of sewage sludge (SS) and fly ash (FA) is a multifaceted problem, which can affect environmental quality. FA has the potential to stabilize SS by reducing metal availability and making the SS suitable for application in the agricultural sector. An experiment was performed to evaluate soil biological quality changes with the combined amendment of SS and FA (fluidized bed combustion ash (FBCA) and lignite fly ash (LFA)). SS was amended with 0, 10, 30, 50 and 100%, (w/w) of FA, and then the FA-SS mixtures were incubated with red soil at 1:1 (v/v). Soil quality parameters such as pH, electrical conductivity, N, soil enzyme activities such as dehydrogenase (DHA), urease (URE), and catalase (CAT), and microbial biomass carbon (MBC) were evaluated at 20, 30, and 60 days of incubation, pH and EC increased with FA-SS dose; however, N decreased. DHA and URE were found to be increased with 10% LFA amendment; thereafter it decreased. However, URE increased up to 30% of FBCA. CAT and MBC increased with both FA amendments, even up to addition of 50% FA. Bioavailable Zn, Cu, and Co contents were decreased by the addition of FA. Principal component analysis showed that pH is the most influential factor. MBC appears to be a sensitive soil indicator for the effects that result from the addition of FA-SS. Phytotoxicity studies with Zea mays showed optimum performance at 30% FA. Addition of 10-30% FBCA or LFA to SS has a positive advantage on soil biological quality.

Obtaining edaphic biostimulants/biofertilizers from different sewage sludges. Effects on soil biological properties

“…[1,2] SS contains high levels of major nutrients, such as N and P, and is rich in organic matter and, therefore, land application is the most commonly used method worldwide and it is considered as one of the most economical methods of sludge disposal. [2][3][4][5] The application of SS to agricultural and degraded soils improves their physical, chemical and biological properties. [6,7] However, SSs are characterized by their high level of metals, organic pollutants and pathogenic organisms that could constitute a contamination source for the soil and groundwater, and may reach the food chain.…”

Seed Germination and Growth Parameters of Zea mays L. as Influenced by Municipal Solid Waste Incineration Fly Ash (MSWIFA) and Sewage Sludge (SS) Amended Soil

“…It has been reported that heavy metal concentrations in a mixture of fly ash (FA) and SS were substantially below the toxicity limits and the results indicated that use of a mixture of FA and SS poses no risk to the food chain [18]. Phytotoxicity studies of the SS -FA mixture with Zea mays L. showed that bioavailability of Zn, Cu, and Co were all decreased by addition of FA [19]. In addition, a reduction of the most bioavailable form of Cd in treated soils (35.4-54.5%) and its transformation into an insoluble fraction was observed when boiler ash was used as a soil amendment; this study highlighted the beneficial effects of waste-products in promoting sugarcane growth and Cd stabilization in soil [20].…”

Synergistic Passivation of Fly Ash and TMT on Heavy Metals in Sewage Sludge

“…The reduction of the exchangeable fraction in the treated sewage sludge might be attributed to the transformation of the heavy metals from soluble salts to insoluble basic salts. Masto et al indicated that the pH increase caused the precipitation of heavy metals in the treated sewage sludge, which was the most influential factor that caused the reduction in diethylenetriaminepentaacetic acid (DTPA)-extractable Zn, Co, and Cu [58]. In addition, fly ash generally possesses many desirable capabilities, such as adsorption, ion exchange, coagulability, and precipitability and shows high performance with respect to heavy metal passivation.…”