Wastewater treatment for schools

A school in Bulgaria, which can only be attended by children whose parents work in the embassies of the various countries, asked for a wastewater treatment plant for schools. Around 80 m³ of wastewater is produced there every day. Those responsible wanted a solution that works reliably, treats the wastewater biologically and is then suitable for direct discharge. For this reason, the pH value should be between 6 and 9, the BOD₅ content below 25 mg/l, the COD content below 125 mg/l and the suspended solids content below 35 mg/l.

The first challenge in this project was the fluctuating wastewater inflow. The wastewater only accumulates during the week until the afternoon. This results in regularly fluctuating inflow peaks, which the treatment plant must compensate for. The second challenge was the different wastewater sources. This consists of hygienic wastewater as well as wastewater from the kitchen and building cleaning. Therefore, fats and oils mix into the wastewater. In combination, the wastewater contains too much COD/BOD₅ and too much suspended matter.

For this project, the ClearFox® team designed an SBR system for underground installation. For the school, the ideal solution was to have the concrete tanks built by a local supplier. To ensure that this was successful, the ClearFox® engineers provided the responsible construction managers with all the details and drawings. The treatment plant consists of two tanks – a buffer tank to balance the inflow peaks and a biological reactor.

At the beginning, the wastewater flows through a grease separator, which separates the oils and fats lying on the water. From there, the wastewater flows directly into the buffer tank. A control unit, which is adjusted to the wastewater load, feeds the wastewater into the biological reactor at regular intervals. This contains the ClearFox® SBR system, which supplies the microorganisms with oxygen. These form an activated sludge which treats the dissolved and non-dissolved substances in the wastewater. After treatment, the wastewater is suitable for irrigation of the school grounds.

The customer chose a ClearFox® wastewater treatment plant because the Bayreuth-based company has many years of experience in wastewater treatment for schools. In addition, he received a particularly cost-efficient system, as transport costs were reduced to a minimum and electricity consumption was especially low. The treatment plant started up quickly. Initial wastewater samples showed that the treatment plant complies with the required discharge values and even falls far below them. This makes the ClearFox® SBR system the ideal solution for wastewater treatment for schools.