FR2725711A1 - Waste water treatment by chemical oxidn. - Google Patents

Abstract

Treatment of waste water, esp. contg. phenolic cpds.,comprises oxidn. at elevated temp. with a mixt. of NaClO3, oxides of Fe and Mn as oxidn. catalysts, and active carbon powder.

Description

PROCESS FOR THE TREATMENT OF PHENOLE RELEASES
Phenolic resins are commonly used in the wading of applied abrasives, thermal insulators, in the manufacture of molds, etc ...: they are indeed very efficient and economical products.

However, manufacturers often come up against the difficult problem of treating their wastewater, because on the one hand the discharge standards are very strict (the concentration, measured in phenol index, must remain below 0.1 mg / l) and d On the other hand, they do not have simple and economical procedures.

Indeed, the techniques currently offered on the market have serious drawbacks - biological treatment with thermophilic bacteria only applies well at concentrations below 100 mg / l (in phenol index) and requires very long residence times ( approximately 1 month), hence the volumes of basins most often prohibitive compared to the available space.

In addition, these purifying bacteria remain very vulnerable to toxic products normally or accidentally present in discharges - the extraction of phenol compounds with butanone followed by fractional distillation requires very expensive explosion-proof equipment - radical oxidation with acid Persulfuric and ozone also requires very heavy investments
The present invention relates to a very simple purification process by hot catalyzed oxidation, using a mixture comprising a very economical oxidant, sodium chlorate, combined with mineral catalysts (iron and manganese oxides) and powdered activated carbon
Oxidation is very fast, it is complete when the final temperature of 900C. is reached
This mixture, thus defined by its chemical composition, has been the subject of a trademark registration (EPUROX reagent, NO INPI 94.519228)
This first treatment phase may be sufficient to treat effluents with an initial phenol concentration of less than 500 mg / l
For higher concentrations, or to save the EPUROX reagent, this first step can be followed by cold catalyzed oxidation in a special electrolysis cell, described in Figures let 2
This cell comprises - two cathodic coopartiments (a) containing aluminum plates immersed in a dilute solution of sulfuric acid - a central anodic carpacment (b) in which circulates 1 effluent to be treated, with
- a central anode (c) made of iron or mild steel or stainless steel, having horizontal grooves (d) facilitating the circulation of gases and effluent
- two counter-anodes (e), kept pressed against the anode, containing mineral oxidation catalysts and in which perforations allow the circulation of the oxidizing gases released at the anode: oxygen coming from the hydrolysis of the water and chlorine from the hydrolysis of the residual chlorate and the chlorides formed during the first treatment phase - an irotoréducteur (f) causing an eccentric and causing by alternating movement the rise and fall of the central anode (c ) between the two counter-anodes (e): this movement ensures the friction wear of the two consumable counter-anodes, the dispersion of the catalysts which they contain in the form of fine particles in the effluent to be treated, as well as the homogenization of this effluent with oxidizing gases and catalysts
This second treatment phase, by cold catalyzed electrolysis, can optionally be applied directly to effluents if the initial concentration of phenols is not too high (less than 500 mg / l)
The electrolysis cell is supplied with direct current at low voltage, from 12 to 48 Volts
The scope of application of these processes is not limited to that of phenolic discharges, but can extend to other types of effluents containing materials which are difficult to oxidize or which have a high chemical oxygen demand.

Claims (1)

 CLAIMS 1- Process for the purification of waste water, in particular phenolic waste, characterized in a first phase by the use of a hot oxidizing mixture containing both sodium chlorate, iron and manganese oxides as oxidation catalysts, and powdered activated carbon 2 - Purification process according to claim 1, characterized by a second phase of treatment by cold catalyzed electrolysis carried out by means of a special cell in which the residual chlorine, originating from the excess chlorate or chlorides produced from this chlorate in the first phase, or already present in the effluent to be treated, is used to oxidize the phenol compounds, in synergy with the oxygen released at the anode and resulting from the electrolysis of water 3 - Process according to claim 2, characterized in that the oxidation catalysts, iron and manganese oxides, are incorporated in two counter consumable anodes 4 - Method according to claims 2 and 3, characterized in that the consumable counter anodes are driven in an alternating movement and that they are kept pressed against the central anode of the electrolysis cell, which allows the gradual release of the oxidation catalysts they contain, as well as the homogenization of the fine particles of catalysts with the oxidizing gases released at the anode, chlorine and oxygen, and with the effluent to be treated