Use of industrial wastewaters for the optimization and control of nitrogen removal processes

In this experimental study the characterization of 2 industrial wastewaters, coming from an ice cream production industry (IW1) and a beet-sugar factory (IW2), with respect to their readily biodegradable fraction and denitrification potential, has been performed. To this end physical-chemical and biological characterization methods, both anoxic and aerobic, were used. Moreover a pilot scale SBR fed with municipal wastewater was started to verify the effect of the gradual addition of the concentrated organic wastewaters during the anoxic phase. The SBR was initially fed only with a primary municipal wastewater, then the organic load was increased by adding to the feed, during the anoxic phase, a small amount of the IW1 (second period). Once the initial conditions were restored the load was again raised using the second industrial wastewater (IW2) (third period). With those additions the nitrogen removal efficiency increased from 26% to 50%, in the case of the IW1 and from 23% to 53% in the case of the wastewater IW2, without any negative effect on the global performance of the system. In addition, periodical kinetic studies of denitrification and nitrification in the SBR, were performed

Release behaviour of MSW-incineration bottom ash after artificial ageing

One of the technologically simplest processes applicable to promote the transformation of bottom ash constituents into a less soluble and more thermodynamically stable forms is accelerated weathering, known also as artificial ageing. This treatment mimics and speeds up the natural weathering processes caused by the contact between ash and atmospheric agents (water, O2 and CO2) and consists on a series of chemical and mineralogical transformations including hydration/hydrolysis, dissolution/precipitation of hydroxides and salts, oxidation/reduction, sorption and ion exchange reactions, as well as formation of solid solutions and clay-like minerals from the glassy phase of the material (Meima and Comans, 1997; Meima and Comans, 1999; Sabbas et al., 2003). In particular, the treatment known as accelerated carbonation simulates the natural weathering processes occurring due to prolonged contact with atmospheric CO2 during temporary storage, utilization or final disposal of incinerator residues