In Hong Kong, there is about 304 sewage treatment facilities in service now, which treat about a total daily sewage flow of 2.8 million cubic meters; where 75% receives chemically enhanced primary treatment (CEPT) and treated at the Stonecutter Island Sewage Treatment Works (SCISTW). SCISTW is one of the biggest worldwide CEPT wastewater treatment, currently treating 17,000 cubic meter of sewage and produces over 800 tons of dewatered sludge per day that will be delivered to Sludge treatment facility (STF) by vessels for incineration. The odor emission was minimized at the SCISTW and STF by carrying out all sludge handling and processing in enclosed environment with strict compliance with establish odor and safety measures including application of deodorizing chemicals and inst...[ Read more ]

In Hong Kong, there is about 304 sewage treatment facilities in service now, which treat about a total daily sewage flow of 2.8 million cubic meters; where 75% receives chemically enhanced primary treatment (CEPT) and treated at the Stonecutter Island Sewage Treatment Works (SCISTW). SCISTW is one of the biggest worldwide CEPT wastewater treatment, currently treating 17,000 cubic meter of sewage and produces over 800 tons of dewatered sludge per day that will be delivered to Sludge treatment facility (STF) by vessels for incineration. The odor emission was minimized at the SCISTW and STF by carrying out all sludge handling and processing in enclosed environment with strict compliance with establish odor and safety measures including application of deodorizing chemicals and installation of odor abatement systems (absorbers, absorbers, scrubbers and biofilters). This study is to investigate and reveal the feasibility of applying MOC hydrogel in dewatered sludge to strengthen the measures taken to decrease H2S odor emission from dewatered CEPT sludge. Malodor Control (MOC) Hydrogel is designed to continuously release of disinfectants and inhibitors that target on micro-organism causes H2S. The disinfectants and inhibitor would suppress the growth and activity of SRB population in the sludge, resulting in prevention of generation of H2S for more than 120 hours. The H2S control effectiveness on dewatered CEPT sludge in 48 hours were evaluated in laboratory scale and bench scale. 1 wt.%, 1.5 wt.% and 2 wt.% MOC hydrgoel have been tested in laboratory, the average suppression is about 88%, 92% and 99% respectively. In bench scale study, 1 wt.% MOC hydrogel suppress over 55% of H2S concentration and 2 wt.% reduced 80% of H2S. In the pilot scale trial, 2 wt.% and 2.6 wt% MOC hydrogel reduce average 50% and 90% of H2S. Nevertheless, with consideration of cost and daily operation work, it is believed that hydrogel required further development to provide a more user-oriented dosing method.