Examination of the Use of Support Materials of Natural Origin in Wastewater Treatment

Abstract

Continuous decrease of discharge limits of purified wastewater and the demand for minimization of investment and treatment costs resulted in new discoveries and technological developments in nitrogen removal from sewages and industrial wastewaters. Almost all the newly recognised processes are based on the NO2– route of the nitrogen removal. The SHARON process comprises an autotrophic and a following heterotrophic nitrogen transformation step. The ANAMMOX process however requires around 1:1 NH4+:NO2– ratio in its influent. Besides the N2 gas production in the process, a small portion of the nitrogen turns into NO3–. Nowadays the practical importance of the aforementioned processes is unfortunately limited to some special wastewater streams, but the utilization of this shortcut of the nitrogen removal in municipal sewage treatment would also be highly beneficial. It appears that according to our practical data collected in specially designed treatment plants for the purification of the wastewater of some animal waste rendering plant and two-stage activated sludge municipal sewage treatment plants the new technologies can easily be realized. The two-stage systems contain two separate sludge cycles in series. Both cycles comprise an aerobic bioreactor and a following mainly rectangular clarifier. The first stage is specially designed for COD removal while the second for autotrophic nitrification. The highly overloaded first stage can remove of the main portion of the influent COD. This way the sludge of the second stage contains 5-10 times more autotrophic microorganisms than the conventional A2/O systems. This results in similar increase in the specific nitrification capacity, while significant simultaneous denitrification can occure.