Within today’s wastewater treatment practice most attention is focused on achieving extensive and stable biological nutrient removal in the activated sludge process, including a stable biological phosphorus removal (Bio-P). The current analytical methods, including sludge activity tests and chemical water analyses, provide no information about specific bacterial groups involved in biological phosphorus removal in wastewater treatment. An assessment of the (biological) phosphorus removal during the activated sludge process is therefore not really possible. A more specific and rapidly conducted method is needed to quantify the bacteria involved in biological phosphorus removal, so that this process in the wastewater treatment can be further optimised and controlled.
This project’s objective is to develop a molecular method [quantitative PCR (qPCR)] for the quantification of the bacteria involved in the biological phosphorus removal, and to test the suitability of this method in determining the quantitative relationships between the occurrence of (dominant) PAOs and GAOs in activated sludge samples and the degree of biological phosphorus removal.
The project leads to the following results:
- Identification of the ‘gene bank’ of specific Bio-P bacteria, including the determination of the potential of the qPCR technique to identify, on the one hand, (dominant) PAOs and, on the other, (dominant) GAOs.
- qPCR method, which enables the quantification of bacteria involved in biological phosphorus removal (PAOs and GAOs).
- Insight into the suitability of the developed qPCR methods in determining the quantitative relationships between the occurrence of (dominant) PAOs and GAOs in the activated sludge samples and the degree of phosphorus removal.
Information was collected from the literature for the development of qPCR tests to enable the quantification of bacteria involved in biological phosphorus removal. On the basis of this information, a selection was made of the most relevant target organisms within the dominant PAOs and GAOs, and specific primers and probes of possible utility for the development of qPCR tests were identified. Subsequently, various qPCR tests were developed in which the DNA of the PAO and GAO bacteria can be specifically detected, and calibration lines were generated thus making quantification possible. Analyses were carried out on samples from wastewater treatment practice. These analyses show that the qPCR tests are potentially applicable as a means, in a short period of time, of getting a picture of the degree of biological phosphorus removal during treatment processes, by measuring the concentration of PAO and GAO bacteria. The research results are set out in a report.