Ho Chi Minh City (HCMC, Vietnam) is one of the fastest growing megacities in the world. In this paper, we attempt to analyse the dynamics of nutrients, suspended sediments, and water discharges in its aquatic systems today and in the future. The work is based on nine sampling sites along the Saigon River and one on the Dongnai River to identify the reference water status upstream from the urban area and the increase in fluxes that occur within the city and its surroundings. For the first time, the calculated fluxes allow drawing up sediment and nutrient budgets at the basin scale and the quantification of total nutrient loading to the estuarine and coastal zones (2012-2016 period). Based on both national Vietnamese and supplementary monitoring programs, we estimated the water, total suspended sediment, and nutrients (Total N, Total P, and dissolved silica: DSi) fluxes at 137 m 3 year −1 , tonSS year −1 , 5,323 tonN year −1 , 450 tonP year −1 , and m 3 year −1 for the Saigon River and 1,693 year −1 , 3,292 2,734 1,175 × 10 3 tonSi × 10 3 tonSS year −1 , 31,030 tonN year −1 , 1,653 tonP year −1 , and 31,138 tonSi year −1 for the Dongnai River, respectively. Nutrient fluxes provide an indicator of coastal eutrophication potential (indicator of coastal eutrophication potential), using nutrient stoichiometry ratios. Despite an excess of nitrogen and phosphorus over silica, estuarine waters downstream of the megacity are not heavily impacted by HCMC. Finally, we analysed scenarios of future trends (2025-2050) for the nutrient inputs on the basis of expected population growth in H C M C and improvement of wastewater treatment capacity. We observed that without the construction of a large number of additional wastewater treatment plants, the eutrophication problem is likely to worsen. The results are discussed in the context of the wastewater management policy.

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Synthetic wastewater with glucose as carbon source was used for cultivation of aerobic granules in sequencing batch airlift reactor (SBAR). Grinded shell powder with diatmeter of 150-200 um used as carrier. SBAR was run at hydraulic retention time (HRT) 5.1 hours, airflow of 4 liters/m and airlift velocity of 4.2 cm/s. The experiment was run at two organic loading rates (OLRs). They were 2.6 and 5.2 kg COD/m°.day, corresponding to influent COD and N-ammonia of 600; 1200 mg/l and 26; 60 mg/l, respectively. After 61 days of running, aerobic granules with size of 1,0-1,2 mm are formed. The size of granules increased to 5 mm at 80th day. Aerobic granules had settling velocity of 36-56 m/h, SVI of 11,4-44.2 ml/g. COD and N-ammonia removal of SBAR were greater than 96% and 75-90%, respectively. It was found that nitrification and denitrification occurred simultaneously in granules.' The COD and N-animonia of SBAR decreased to 70% and 51%, respectively when filamentous sludge bulking and viscous bulking appeared simultaneously.