CONSTRUCTION AND COMMISSIONING OF HIGH AIR FLOW CAPACITY WET CHEMICAL SCRUBBERS

摘要

This paper discusses the experiences and lessons learnt from the construction and commissioning of the refurbished and upgraded Odour Control Facility (OCF) at Malabar Wastewater Treatment Plant (WWTP). The OCF consists of six wet chemical scrubber units operated in parallel and has the highest air flow capacity of any odour control facility in the southern hemisphere, treating a total foul air flow of 180 cubic metres per second (180 mVs or 648,000 mVh) across four duty and two standby scrubber units under normal operation. As part of the commissioning process, several key areas for improvement were identified and implemented; these included the optimisation of chemical dosing through feed forward control and the determination of the system air flow without the use of a traditional flow meter. In addition, the process performance was measured through online monitoring of the feed and discharge air hydrogen sulphide (H_2S) and discharge air chlorine (Cl_2) concentration; spot measurements of odour concentration through dynamic olfactometry; and gas constituents through gas chromatography-mass spectrometry. Preliminary testing of the upgraded OCF shows it has demonstrated compliance with strict performance requirements of less than 1,000 odour units (OU) and less than 50 parts per billion (ppb) of hydrogen sulphide in the exhaust gas stream. The preliminary stages of the OCF upgrade have been met with positive feedback from the Sydney Water plant operations team due to improved process performance, reliability and ease of operation.%Chemical scrubber, hydrogen sulfide, odour, sodium hypochlorite, sodium hydroxide