Objective
Photocatalysed biological coupling in the degradation of toxic industrial pollutants via an ergonomic unit has been the subject of intensive research during the past year. The first stage consists of a photocatalytic TiO2 based unit that uses H2O2 generated from an electrolyser being fed by state-of-the-art solar cell technology. The second step involves efficient Fenton treatment of the pollutant material allowing deeper penetration of light. The third stage consists of a fixed bed bacteria biodegrading the pre-treated pollutants. This step completes the mineralisation of these toxic materials in a low cost process.
The multiple phase reactor comprises specific times of degradation of the triple, double or single aromatic ring compounds. The times of degradation of the aromatic moiety (in each case) is determined by NMR and HPLC techniques as a function of time. This reactor has shown promising results in the degradation of phenolic compounds, quinones, halocarbons, pesticides and dyes. This invention combines a photocatalytic TiO2 cell with an H2O2 electrolyser fed by solar panels delivering about 100W/m2 energised by solar cells delivering 20 ma and 850 mV. This invention of a new ergonomic unit for pollutant destruction combines recent scientific and technical advances in the NIS and west European countries.
The following results are expected: the improvement of the head of the reactor consisting of TiO2-granulated pellets separating the charges on this semiconductor under light and efficiently generating the peroxide radical needed to destroy the organic pollutant. The geometry of the head cell will be modified to optimise the interaction with the incoming (scattering) light and the kinetics of the radical generation during the degradation process.
The peroxide needed to generate the OH radicals in the head reactor is made available in a stream containing the pollutant. Initial tests show a reactor used with a flow of 0.3 l/min or 20 l/h. It is expected to put up this flow to 200 l/h or about 5 cubic meters/day. It is also expected that reactors in parallel can handle 50 cubic meters/day of the effluents of a small industnal site. Photocells are currently being developed and the electrolyser needs about 2 V and 10 ma if it is going to produce 10-5 M hydrogen peroxide/minute. A relation of 100 to 1 is a suitable ratio to be used between the peroxide and the impuritity to be destroyed. Higher concentrations of impurities will need a higher output in terms of milliamperes and in the next two years such an improvement is expected. A biological stage will be added after the head reactor in the multistage reactor to degrade the pollutant fully once the toxic and recalcitrant part of the pollutant has been taken care of via the semiconductor photo-catalytical pretreatment. The functional groups that have to be destroyed prior to the use of this biological stage are the aromatic single or multiple rings, and the functional groups like -SO3H, - NO2 and the Cl-group.
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1015 Lausanne
Switzerland