Abstract:The study has assessed the denitrification performance of fermented and dark-fermented biosolids as external carbon sources using lab-scaled Sequencing Batch Reactors (SBRs). This was done by adding fermented and dark-fermented biosolids into anoxic zones of two SBRs, and then assessing the change of effluent characteristics comparing to before adding and to a third controlled reactor. The results showed that by adding 150-170 mg rbCOD/L of either of the selected fermented biosolids, almost complete denitrification could be reached for tested SBRs (reduced from initial ~20 mg NO 3 /L to < 1 mg NO 3 /L). Finally, the experiment also found that the impact of NH 4 components of fermented and dark-fermented biosolids onto the final effluent were much lesser than expected, where only less than 2.5 mg NH 4 /L were detected in the effluent, much lower than the added 5.0-5.7 mg/L.

The charging flocculation agent “Kiyomaru” is a natural inorganic substance produced from volcanic ash (“Shirasu”) by calcining it in the special firing furnace to generate high porosity, then applying a strong electric charge to some substances included in the ingredient of “Shirasu” by special processing. “Kiyomaru” consists of 24.7 % Na, 11.5 % Al, 19.6 % Si, 22.5 % S, 1.8 % K, 19.0% Ca, 09% Fe, which can consider as an ecological water depurative, having rapid rate of flocculation and sedimentation, cheaper facility cost, simplification of post-processing sludge, low cost and high performance, overwhelming flocculation capacity. Apart from effective treatment of the waters contaminated with high content of suspending solid (up to 10,000 ppm), the agent can remove some heavy metals such as Fe, Mn, As, etc., odour and some organic substances (COD). From 2013 to the present, Environmental Technology Center (ENTEC) in cooperation with HALVO Company Ltd. and Japan Port Consultants Ltd. funded by the Department of Science and Technology of Vinh Long prpvince have implemented the study on experiemental study on application of “Kiyomaru” for catfish farming water treatment in Vinh Long province. The obtained results shown that when using the “kiyomaru”, the efficency of color, turbidity, suspended solid and iron removal as well as the rate of coagulation and sedimentation are generally higher than those comparing with the traditional coagulants.

Abstract:The aim of this study was to assess the impact of industrial-grade sucrose as external carbon source on post-anoxic denitrification. This was done through the use of lab-scaled Sequencing Batch Reactors (SBRs) modelling after a standard post-anoxic Waste Water Treatment Plant (WWTP). Each reactor holds an effective volume of approximately 4 L, with the decant volume of 2 L per cycle, a Hydraulic Retention Time (HRT) of 8 hours, Sludge Retention Time (SRT) of about 11.5 ± 0.5 days. The experiments showed that adding industrial-grade sucrose into the post-anoxic zone has a very significant improvement where the nitrate removal rate increased from 10% to 68%. The experiment also verifies that most of the Specific Denitrification Rate (SDNR) calculated from the lab-scaled SBRs lie within the range of earlier study (2.29-2.85 mgNO 3 -/gMLVSS/h), and verified the results of both this experiment and the SDNR batch tests in previous study.