Articles

The temperature influence upon the nitrification rate was studied using a continuous flow pilot installation, which comprises a biological aerated filter with ascendant inflow circulation. Used filter media was expanded clay, 2-5 mm granulometric fraction. The biofilter was fed with raw low - depth groundwater enriched with NH+ 4. Inorganic nitrogen forms (NH4+, NO2-, NO3-) concentrations were measured both within the inflow and outflow of aerated biological filter, at stationary operation regimes in correspondence with various applied NH+ 4 loading. Values of NH4+removal rates were situated within the 515-1337 g NH4+-N/m3*day domain for temperature increase from 11 to 25.2 C degree. The coefficients of reaction rate vs. reaction temperature equation were also determined.

Mine water from abandoned mines and spoil heaps from closed mining perimeter may generate significant surface water pollution. In Romania there are tens of sources with moderate to high contamination. Mine water flows have to be treated to meet national regulation NTPA 001/2005 for discharging in surface waters as any wastewater in any water body: low limits for heavy metals, but also for species considered benign to a certain level – calcium, magnesium and sulfate. By lime precipitation treatment, some CaSO4 can be formed, lowering the [SO42–] level, but the limit for sulfate will not be achieved, because the concentration correlated to gypsum solubility exceeds it by roughly three times. Sulfate precipitation as ettringite is a robust multi-stage technology (ECOIND- WISUTEC 2007–2012), but the costs are not reasonably sustainable for long term. Some approaches for modified technological flow-sheets and laboratory test result for the valorisation of reactive aluminium sources (e.g. mine water aluminium or flows with wasted aluminium).