Ecology & Safety, Volume 9, 2015

Abstract: Continual measurement on flow rate and wastewater regime in sewage systems is a new activity resulting from the synchronization of legislation on environmental protection of Bulgaria with the European requirements. The existing sewer systems are mostly of the mixed type – for domestic-industrial and rainwater runoff. The water of the first type is of ecological interest and is orders of magnitude less in quantity than rainwater. A large-scale research program for monitoring of wastewater regime and quantity is aimed at overcoming the above issues. The developed hydrometric equipment corresponds to almost all conditions and status of sewer systems in Bulgaria. A range of typified hydrometric devices is worked out for pipe diameters from Ф160 to Ф300 mm. They are suitable for measurement of non-stationary water flows and create minimal backwatering level in the pipes and minimal prerequisites for retention of suspended matter, ensuring high accuracy for minimal values of water quantity. The adopted principle of typifying has the advantages of easy installation, accurate “wet zero” adjustment and an option for laboratory calibration allowing the expansion of the operation range and offering the possibility to create geometrically similar models. Experimental models are in successful operation on a number of sites in Bulgaria.