Pleurotus ostreatus spent mushroom compost as green biosorbent for nickel (II) biosorption.

The potential of Pleurotus ostreatus spent mushroom compost (PSMC) as a green biosorbent for nickel (II) biosorption was investigated in this study. A novel approach of using the half-saturation concentration of biosorbent to rapidly determine the uptake, kinetics and mechanism of biosorption was employed together with cost per unit uptake analysis to determine the potential of this biosorbent. Fifty per cent nickel (II) biosorption was obtained at a half-saturation constant of 0.7 g biosorbent concentration, initial pH in the range of 4-8, 10 min contact time, 50 mL 50 mg/L nickel (II) initial concentration. The experimental data were well fitted with the Langmuir isotherm model and the maximum nickel (II) biosorption was 3.04 mg/g. The results corresponded well to a second pseudo order kinetic model with the coefficient of determination value of 0.9999. Based on FTIR analysis, the general alkyl, hydroxyl or amino, aliphatic alcohol and carbonyl functional groups of biosorbent were involved in the biosorption process. Therefore, biosorption of nickel (II) must involve several mechanisms simultaneously such as physical adsorption, chemisorption and ion exchange. Cost comparison for PSMC with Amberlite IRC-86 ion exchange resin indicates that the biosorbent has the potential to be developed into a cost effective and environmentally friendly treatment system.

Supplementation of ammonium bicarbonates for the treatment of fruit cordial wastewater by anaerobic digestion process.

Lack of nitrogenous substrate and buffering capacity have been identified as causing failure in previous work on the treatment of fruit cordial wastewater using anaerobic continuous stirred tank reactors. In this study, ammonium bicarbonate was proposed to be used as the substrate for nitrogenous and buffering resources. In order to determine the toxicity effect of the ammonium salts on the anaerobic system, a series of concentration from 0 to 40 mg L(-1) was tested. Biogas production was used as the indicator for NH4+ toxicity. The results showed no indication that methanogen was affected by the additional ammonium salt within the dosing regime. Application of the specific mathematical function (G=G(m)(k)(/t)) to describe the kinetic of biogas production, suggested that the optimal concentration of ammonium bicarbonate that can be used is 10 mg L(-1). This study also shows that the dosage regime up to 40 mg L(-1) can be used to supplement the lack of nitrogenous and buffering capacity for the anaerobic digestion process of the fruit cordial wastewater using CSTR.