PROBEST ALLICATIONS / Hainan Wuzhishan Sewage Treatment Plant Instruments for Water Inlet. The new instrument project for water quality monitoring at the inlet of the Wuzhishan Sewage Treatment Plant and Changhao Township Sewage Treatment Plant is one of the projects to optimize the efficiency of urban sewage treatment. The installation was completed in August this year. The project uses PROBEST instruments including: PCM-NH3N ammonia Online automatic monitor, PCM-CODcr chemical oxygen demand online automatic monitor, PCM-TN total nitrogen online automatic monitor, PCM-TP total phosphorus online automatic monitor, PSS-800 suspended solids/sludge online analyzer, PPH-500 PH online analyzer.