The new Bialystok University of Technology patent is the result of several years of research of scientists from the Faculty of Civil Engineering and Environmental Sciences

– Oxygen activated sludge granules are the subject of research we have been conducting for several years. A patented granulation method is one of their results. The method we have developed can be implemented in wastewater treatment plants where the technological sequence is based on the use of sequential biological reactors, emphasises Piotr Ofman, PhD, Eng, co-inventor of the invention.

The technology for wastewater treatment using aerobic granular activated sludge is an innovative method. Although it was invented and implemented almost a decade ago, it is used in only a dozen industrial and municipal wastewater treatment plants around the world. In Poland, it is used in the treatment plant serving the town of Ryki. The reason for this may be the still ongoing basic research into granulated activated sludge.

The method developed by scientists of Bialystok University of Technology involves using a consortium of micro-organisms to biodegrade carbon compounds, forms of nitrogen and phosphorus. The biomass formed in this process takes the form of granules and settles much faster than conventional flocculent activated sludge. This property reduces, among other things, the need for multi-chamber reactors and recirculation, which can solve a number of operational problems and reduce the operating costs of wastewater treatment plants.

– Among the most important advantages of aerobic activated sludge granules is their resistance to changes in the quality characteristics of the effluent flowing into the treatment plant. This property allows for more stable effects of biological removal of pollutants present in the wastewater. In addition, aerobic granular activated sludge has better sedimentation properties compared to the most common activated sludge in wastewater treatment plants – flocculated sludge. This property has the potential to solve a number of operational problems and reduce the operating costs of wastewater treatment plants. In addition to this, the improved sedimentation properties of aerobic activated sludge granules indirectly result in the possibility of shortening the operating cycle of the sequencing reactor, namely I am referring to the sedimentation phase. This makes it possible to plan the operating strategy of the reactor in a different way and, consequently, to reduce investment costs associated with the construction of retention tanks for storing raw sewage, says Ofman, PhD, Eng.

In the course of the research, the scientists also observed that aerobic activated sludge granules grow slightly slower compared to activated sludge flocs. This would translate into a partial solution to sludge management problems in wastewater treatment plants, by having to manage the smaller mass of excess sludge that has to be discharged from the wastewater treatment system.

A team of scientists from the Faculty of Civil Engineering and Environmental Sciences of Bialystok University of Technology has been conducting research into the granulation of flocculated activated sludge for several years. It uses, among other things, a sequential biological reactor of the SBR type designed by Piotr Ofman, PhD, Eng.

– Last year, we carried out a research project funded by the National Science Centre devoted to analysing the transformation of nitrogen forms during the granulation of activated sludge flocs. The results of this project allowed us to gain a better understanding of the treatment process using aerobic activated sludge pellets and, consequently, we observed that the kinetics of the transformation of nitrogen compounds increases with the degree of granulation of the activated sludge. Thus, it is possible to reduce the time of the aeration phase while maintaining the required quality of the treated effluent. It should be noted that aeration is one of the most energy-intensive processes in wastewater treatment plants. Hence, the possibility of reducing the aeration time of the wastewater translates into a reduction in operating costs associated with electricity consumption, explains Piotr Ofman, PhD, Eng.

As part of their research, a team led by Piotr Ofman, PhD, Eng, has shown that the intensity with which nitrogen forms are transformed increases with the degree of granulation of the activated sludge. Currently, the researchers are working on modifying a patented method of granulating flocculated activated sludge. In the broader perspective, the research results will also be applicable in the industrial branch.

– Receiving the patent will make it easier for us to obtain funding for further research, which we would like to conduct on a larger scale and, if possible, under real conditions, explains Piotr Ofman, PhD, Eng.

by mr