Biostimulation of azo dye-contaminated soils by food industry sludge

Abstract

The release of synthetic organic dyes into agricultural lands may pose serious environmental problems due to probable stress effects on the natural equilibrium of soils. Remediation of dye-threatened soils by means of effective and economic methods is, therefore, urgently required especially in developing and underdeveloped countries. In this study, biostimulation effect of canned food industry sludge on dye-contaminated soils was evaluated by the response of nitrogen-related processes in soil. For this purpose, varying doses of Reactive Black 5 (RB5) and Sulfanilic acid (SA) were added to soil pots. Following a pollution period of 60 days, sludge samples were added to each pot (100t/ha) and the mixtures were further incubated for 30 days. The results indicated that exposure to RB5 ( = 40 mg/kg dry soil) and SA( = 32 mg/kg soil) apparently reduced (10% to 27%) the urease activity, arginine ammonification rate, nitrification potential, and ammonia oxidisers in soil. The results of the biostimulation period showed that the examined parameters in RB5- and SA-contaminated soils responded positively (3% to 36%) to the application of wastewater sludge. Accordingly, it is concluded that wastewater sludge from canned food industry may be used as an effective and economic biostimulating agent for agricultural lands polluted with synthetic textile dyes and related metabolites.