On-line automatic sampling for real time monitoring of wastewaters

An on-line automatic sample collection system for real time monitoring of wastewater treatment has been built and tested at a sewage treatment plant. The system consists of an effluent filtration cell, a sample collection and discharge unit and a control system. It automatically provides a clear sample, which is free of particulates larger than 0.45 μm in size, at predetermined sampling frequency and sample quantity. On-site trials have shown that this system has high transmission (> 90%) for species to be analysed, namely nitrogen and phosphorus, and reasonable transmission (> 70%) for dissolved organic carbon, and has the potential to be utilised for real time sampling. Thirteen days of continuous operation of the system without supervision have been achieved.