The paper starts by reviewing the increasing production of waste and the growing importance of its thermal treatment, which aims at volume reduction of the waste, at the destruction, capture, and concentration of hazardous substances, and at the recovery of energy (WtE).
Industrial wastewater may contain high molybdenum concentrations, making treatment before discharge necessary. In this paper, the removal of molybdate anions from water is presented, using clinoptilolite zeolite coated with magnetite nanoparticles. In batch experiments the influence of pH, ionic strength, possible interfering (oxy)anions, temperature and contact time is investigated. Besides determination of kinetic parameters and adsorption isotherms, thermodynamic modeling is performed to get better insight into the adsorption mechanism; molybdenum is assumed to be adsorbed as a FeOMoO 2 (OH).2H 2 O inner-sphere complex. At the optimum pH of 3, the adsorption capacity is around 18 mg molybdenum per gram adsorbent. The ionic strength of the solution has no influence on the adsorption capacity. Other anions, added to the molybdenum solution in at least a tenfold excess, only have a minor influence on the adsorption of molybdenum, with the exception of phosphate. Adsorption increases when temperature is increased. It is demonstrated that the adsorbent can be used to remove molybdenum from industrial wastewater streams, and that the limitations set by the World Health Organization (residual concentration of 70 lg/l Mo) can easily be met. Water Environ. Res., 84, 753 (2012).
Blocking of the collection hoppers of the baghouse filters in a fluidized bed incinerator for co-incineration of high calorific industrial solid waste and sludge was observed. The composition of the flue gas cleaning residue (FGCR), both from a blocked hopper and from a normal hopper, was investigated by (differential) thermogravimetric analysis, quantitative X-ray powder diffraction and wet chemical analysis. The lower elemental carbon concentration and the higher calcium carbonate concentration of the agglomerated sample was the result of oxidation of carbon and subsequent reaction of CO2 with CaO. The evolved heat causes a temperature increase, with the decomposition of CaOHCl as a consequence. The formation of calcite and calcium chloride and the evolution of heat caused agglomeration of the FGCR. Activated lignite coke was replaced by another adsorption agent with less carbon, so the auto-ignition temperature increased; since then no further block formation has occurred.
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