Microbial Removal of Drug Pharmaceutical Residues from Organic Sewage Sludge

It is a global necessity to pay more attention to the ever increasing pollution of the waters. To preserve the water bases and provide them with an adequate protection is a great challenge as is the cleaning of polluted water, too. Conventional wastewater treatments are not suitable to remove all the incoming pollutants in the treatment plants. That is the reason why NYÍRSÉGVÍZ ZRT. (Nyíregyháza and Conurbation Water and Canalization Closed Shareholder Group) has started a new development program.

According to data in the literature, pharmaceutical agents appear in an ever growing quantity in surface waters, in waste waters and in purified sewage (Poseidon project: Contract No. EVK1-CT-2000-00047). International literature emphasises the need to focus the risk management strategies on the removal of drugs from sewage (Kümmerer, 2009) and to give a major role to microorganisms in the removal of drug residues (Kraighera et al., 2008).

The majority of the pharmaceutical agents is discarded with urine and accumulate in sewage. Drug residues getting into the living water adversely affect living organisms and the ecological balance through the food-chain, too.

Waste treatment plant 1 of NYÍRSÉGVÍZ ZRT.

In its innovative development project, NYÍRSÉGVÍZ ZRT set the target to examine the possibility of the removal of non-steroidal anti-inflammatory and pain-killer drug agents concentrated in sewage with the help of microorganisms, and in addition to incorporate this method into the state-of-the-art technologies using organic sludge. The quantity of drugs taken by the population and their environmental persistence was taken into consideration in the process of choosing the agents. Based on these factors the tests focused on the agents ibuprofen, diclofenac, ketoprofen and naproxen.

According to the literature and the results of own initial state tests, microorganisms which remove the drug agents are already present in sewage systems. In the course of the project those microbes were selected, isolated and later tested in laboratories which have proved to be effective in removing the drug agents. Following the determination of their optimal ratio, the bacteria were propagated and returned to the system.

The pilot plant equipment is a steel structure with a 10 m³ capacity mixed-base, continuous-flow, excess sludge removing system built by NYÍRSÉGVÍZ ZRT.

Micro-organism strains

Following the successful pilot plant results, the experiment was continued in an operational environment in the sewage plant in Levelek which has a daily capacity of 660 m³. According to the measurements, the effectiveness of the activities of microorganisms in removing the tested agents was on average >90%, and further tests proved the stability and sustainability of the procedure.

It is important that extraneous and genetically modified microorganisms do not get into the system.

The major part of the agents eliminated from the water accumulates in the sludge.

Operational Experiment

NYÍRSÉGVÍZ ZRT recycles the whole amount of sludge formed in the sewage plants using the process of anaerobic digestion (biogas production), followed by composting.

The results of the tests show that the concentration of agents during the process of sludge treatment demonstrates a progressively decreasing tendency. In the prepared compost the amount of all tested agents is under the detection limit.

Composting

The result of the innovation project is that the drug agents present in the incoming sewage can be effectively removed. This successful research and development project brought NYÍRSÉGVÍZ Zrt the Northern Great Plains Regional Innovation Award in November 2012.

Further information

Nyíregyháza and Conurbation Water and Canalization Closed Shareholder Group

Address: H-4400 Nyíregyháza, Tó u. 5, POB 290

Tel: +36-42-523-600, toll free number: +36 – 80 – 204 – 044

Central e-mail address: nyirsegviz@mail.nyirsegviz.hu

Web: www.nyirsegviz.hu