Hidrológiai Közlöny 1982 (62. évfolyam)

5. szám - Dr. Benedek Pál–dr. Farkas Péter: A biológiai és a harmadlagos szennyvíztisztítással elérhető szerves mikroszennyező eltávolítás

Dr. Benedek P.—

dr. Farkas P.: A biológiai Hidrológiai Közlöny 1982. 5. sz. 219 [46] Hoffmann, I. et al.: Kritischer Vergleich von Vor-Simultan- und Nachfällung anhand von schwedischen und schweizerischen Erfahrungen. 10. Essener Tagung 1977. GWA. Heft 25. RWTH Aachen, NSZK 1978. [47] Gros, H. and Mörgeli, B.

: Optimal advanced treatment and phosphorus removal by deep bed filtration. IAWPR 10th Int. Conference, Toronto, Canada, 1980. [48] Benedek., P. és Licskó. I.: Szervetlen mikroszenynyezők eltávolítása ivóvízből. Hidrológiai Közlöny, 12. sz. 1980. OreneHb YAAJIEHHFL opraHHMecKHX MHKpo3arpfl3HHTejieii npw ßHOJiorHMecKOü BOAOOMHCTKe h OHHCTKC TpeTbefi CTyneHH d-p BeHedeK, 77. icant). mexH. nayK—d-p <t>apKaui, H. no npH3HaKaM ßHOflerpa^auiiH opraHUMeooie BemecTBa pa3«eji5iH)TC5i Ha Tpw rpynnbi: npenMymecTBeHHO O^HOpo/iHbie no cocTaßy AMeeK, aHajioniMHbie H unT0My>Kbie. OpraHHMecKHe MHKp03arpji3HHTejiH npuMHCJiaioTCji K nocjieaHHM «ByM rpynnaM. 3(J)(j)eKTiiBH0CTb SHOJIOI-HMCCKoii OMHCTKH oxBaTbmaeT Bee TpH rpynnbi, OÄHaKO yaajieHHe 3arp?i3HHTe^eii nocjieflHeft rpynnbi BO3MO>KHO TOJibKO MacTHMHO-npHMeHeHHeM a6cop6iiHH H crpunnHHr MexaHH3M3. CaMa6H0J10rHMeCKa>I OMHCTKa np0H3B0«HT HeKOTopbie MeTaöojiHTbi, noflBJinromHecfl 3aTeM B ownmeHHoii BO^e. üapaflOKcajibHO, MTO MeM Sojibuie npeőbisaeT CTOMHajI BO^a B CHCTGMe a 3H3MHT, MeM Bblllie B03M0H<H0CTb pa3Jio>KeHHíi TpyaHopacTBopHMbix oprauHMecKHX 3arpiisHHTejieii, TeM Sojibuie np0,rtyKT0B pa3Jio>KeHHíi jiMeeK nona^aeT CHOBa B pacTBop. H

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—Dr. Farkas P. Organic substances can be classified according to their biodegradability into three groups, namely the overwhelmingly cell-identical compounds, the analogues thereof and those that do not originate from the cells. The bioresistant substances, and specifically the organic micropollutants belong to the latter two groups. While each of the three groups is affected to some extent by biological treatment, the pollutnats belonging to the last group can only be removed by adsorption and — if they are volatile —- by stripping mechanisms. Even these are effective to a limited extent only. The biological treatment process itself produces metabolites, which are difficult to decompose and these appear then in the treated effluent. Paradoxically, the longer the detention time of sewage in the system, and conseqviently, the greater the opportunity of degrading a greater number of less readily decomposable organic pollutants, the larger becomes the amount of cell decomposition products entering solution agaim The „total oxidation method" alone is thus a tool of questionable value in removing the bioresistant substances, which give rise to the residual COD. In view of the foregoing problem, it was deemed necessary to approach the process of activated-sludge wastewater treatment by new kinetic relations, including the phenomenon of by-product formation. Moreover, it has been found necessary to introduce index numbers, by which biodegradability can be measured. Realizing that the major part of the undegradable micropollutants, and even some of the metabolites leave the system together with the suspended solids present in the treated effluent, attention has been concentrated on final sedimentation. A method has been developed for controlling the sludge budget in terms of the sludge level in the final sedimentation tank. The tertiary methods of wasterwater treatment are, in effect, applied supplementary to the biological processes, and tend to improve the coagulation-, adsorption* and filtration (suspended matter removal) mechanisms of the biological system. These physical- and chemical methods are applied simultaneously, or in succession. The results achieved in connection with the coagulation-precipitation methods have already been described in a previous article. Based on extensive experimental evidence obtained in pilot-plant scale, design instructions have been compiled for double-layer, downward-flow filters, which proved most effective under the conditions prevailing in Hungary. The addition of powdered activated carbon the activated sludge has been tested in laboratory- and plant experiments alike. A very high efficiency in the removal of micro-pollutants had been observed and attributed in part to the increased adsorption capacity, in part to the intensified biological activity and in part to the higher settling rate of the suspended solids. Using the analytical results published in the foreign literature and obtained here, the cost factors of tertiary treatment methods and the improvement in removal efficiency attainable thereby have been compared with regard to the main group characteristics of the micro-pollutants, viz. suspended solids and COD. The analysis has shown the admixtűre of powdered activated carbon to the biological sludge to be a relatively economical solution, at least at minor plants designed to treat a sewage flow equivalent, to that produced by 10 000 inhabitants.