Treatment Of Simulation Dyeing Wastewater With Acid Rose Red By Manganese Sand Filled Ozone Biological Aerated Filter

In China, more than90%of textile industry is concentrated in the coastal areas, and theexcessive concentration of industry has made the total discharge of pollutants exceed theenvironmental capacity in some regions, so that it is imperative for the textile and dyeingenterprises to achieve advanced treatment or even reuse of wastewater. This paper focused onthe treatment of acid rose red simulated dyeing wastewater by integrated ozone biologicalaerated filter (BAF), which is a new kind of wastewater advanced treatment facilities.In this paper, a packed column ozonation reactor was employed to simulate theozonation reaction that occurs in the lower layer of ozone BAF, and it was found that the glassballs filled column possessed higher mass transfer rate and conversion efficiency of ozonethan the empty column reactor and allowed better treated effluent under the same conditions,indicating that ozone BAF had a higher performance than conventional contact ozonationreactor because of the shearing action by the fillers. In order to improve the performance ofozone BAF, a comparative study of glass balls, ceramic pellets and manganese sands filledcolumn reactors was carried out. Manganese sands were found to allow the highest utilizationof ozone and reduce the ozone concentration of water and outlet air effectively. Both ofceramic pellets and manganese sands filled column reactors had similar COD removalefficiency, which was higher than that of glass balls filled column reactor. There was nosignificant difference in color removal among the three reactors while the hydraulic retentiontime was longer than2minutes. The removal effects of aromatic compounds by the threereactors were almost the same under alkaline conditions, while the glass balls filled reactorshowed lower removal efficiencies under acid conditions. However, the improvement ofbiodegradability of simulation wastewater by manganese sands filled or ceramic pellets filledreactors was slightly inferior to that of glass balls filled reactor.The degradation rules of acid rose red along the three reactors were also studied. Underthe same conditions, manganese sands filled reactor could obtain faster comprehensivedegradation rate, and a removal rate of more than90%was achieved at the height of60cm ofpacking layer. Besides, the decolorization of acid rose red was proved to be achieved by directozone oxidation, and when it came to the later stage of intermediate degradation, ozone could be decomposed into hydroxyl radicals with catalysis by manganese sands, which also playedan essential role in the reaction.This paper also investigated the optimal operation conditions of the manganese sandsand ceramic pellets filled ozone BAF. Within certain limits, it was found that the higher heightof manganese sand packing layer, the better treatment efficiency was obtained. The biomassand bioactivity in manganese sand layer were extremely low, but in the ceramic pelletspacking layer, the biomass increased in the direction of flow, while the bioactivity showed anexponential growth first and then turned to a slightly decline along the reactor.As the application of this research in a cooperation project, integrated ozone BAFs werefirst applied as pretreatment process in an actual textile effluent advanced treatment project toimprove the feed stream of membrane separation system. Monitoring data showed that, thecombined process could obtain high quality reclaimed water and guarantee the major pollutantindexes of RO concentrate meet the local discharge standards, allowing direct emissionwithout further treatment.