Fig 7 - uploaded by Mark Christian Felipe Reveche Redillas
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Total alkalinity released from the media (Ca 2+ as hardness, represents Alksupp trend) packed beds continuously fed with sulfate laden synthetic solution.
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Three packing materials for sulfur oxidizing denitrification packed bed systems seeded with acclimated anoxic sludge were evaluated. Two porous media were prepared via thermal fusion with sodium bicarbonate as porogen: sulfur fused with powdered (1) calcium carbonate (CaCO3) (SCa) and (2) oyster shell (SCr). Randomly packed sulfur and limestone gra...
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... tot values can be compared if Alk supp values are available for comparison. Hardness profiles in Fig. 7 could roughly represent Alk supp trend. Results revealed that highest Alk supp was obtained in SCr, followed by S + L then SCa for all HRT conditions. With con- stant Alk in (310 mg CaCO 3 /L), Alk tot hence would follow the same trend: SCr > S + L > SCa. Thus, the highest Alk tot albeit lowest Alk eff values in SCr clearly suggest ...
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The use of reduced sulfur compounds as electron donors for biological denitrification has the potential to reduce chemical and sludge disposal costs as well as carry-over of organic carbon to the effluent that often occurs with heterotrophic denitrification. Although a number of prior studies have evaluated sulfur oxidizing denitrification (SOD), n...
Citations
... Studies have revealed that Thermomonas is a typical autotrophic denitrifying bacterium, and that its genus have the functions of hydrogen autotrophic denitrification, iron autotrophic denitrification, and sulfur autotrophic denitrification [30,31]. There are also small amounts of the obligate iron autotrophic denitrifying bacterium Ferritrophicum and the obligate sulfur autotrophic bacterium Thiobacillus in the sludge samples on the surface of the sulfur particles [32]. ...
Mixotrophic denitrification has showed great potential for treating wastewater with a low C/N ratio. Mixotrophic denitrification is the process combining autotrophic denitrification and heterotrophic denitrification in one system. It can compensate the disadvantage of the both denitrifications. Instead of using sodium acetate and glucose as carbon source for the heterotrophic denitrification, agriculture solid wastes including rice straw (RS), wheat straw (WS), and corncob (CC) were employed in this study to investigate their potential as carbon source for treating low C/N wastewater. The carbon releasing pattern of the three carbon rich materials has been studied as well as their capacity in denitrification. The results showed that the highest denitrification occurred in the corncob system which was 0.34 kg N/(m3·d). Corncob was then selected to combine with sulfur beads to build the mixotrophic denitrification system. The reactor packed with sulfur bead on the top and corncob on the bottom achieved 0.34 kg N/(m3·d) denitrification efficiency, which is higher than that of the reactor packed with completely mixed sulfur bead and corncob. The autotrophic denitrification and heterotrophic denitrification were 42.2% and 57.8%, respectively. The microorganisms in the sulfur layer were Thermomonas, Ferritrophicum, Thiobacillus belonging to autotrophic denitrification bacteria. Kouleothrix and Geothrix were mostly found in the corncob layer, which have the function for fiber hydrolysis and denitrification. The study has provided an insight into agriculture solid waste application and enhancement on denitrification of wastewater treatment.
The effect of particle morphology on denitrification performance in element sulfur-based denitrification (ESDeN) packed-bed process is a gap. In this study, three different types of commercial sulfur particles were selected to build the ESDeN reactors. The results showed the reactors filled with rougher sulfur particles took shorter time to reach stable denitrification performance in the start-up stage. The reactors filled with cap-shape sulfur particles received the maximum nitrate removal rate of 849.49±79.29 g N·m⁻³·d⁻¹ at empty bed contact time of 0.50 h, which was 2.34 times higher than that with ball-shape sulfur particles in the steady stage. The superior denitrification performance in the cap-shape particles set linked to its larger effective volumetric surface area (ωe, 1.67 times larger) and to the longer actual hydraulic retention time (AHRT, 1.80 times longer). This study extends the knowledge of the dependency of sulfur particle properties on denitrification performance in ESDeN packed-bed reactor.
In this study, four sulfur-based carriers (C1-C4) which have different mass ratio of sodium silicate to carrier from 30% to 50% (C1-C3) and the existence of water (C4) were prepared in order to evaluate the effect of the different physical properties on denitrification in sulfur-based autotrophic processes. While the apparent density and the compressive strength decreased as the proportion of sodium silicate increased and water was added in the carriers, the average pore size and the porosity increased from 0.43 to 3.13 µm and from 38% to 67%, respectively. The treatment system using the carrier C4 with the highest surface area was stabilized most rapidly and achieved the highest nitrogen removal efficiency of 85.6 ± 5.0% during a relatively short HRT of 3 hours. The efficiency of nitrate removal was enhanced by 36.9% due to the increase of the ratio of sodium silicate in the carriers from C1 to C3, and more 4.8% point of removal rate increased in the carrier C4 by adding water to the carrier C3. The sum of Thiobacillus and Sulfurimonas was obtained up to 65.90% among the microbial community in the carrier C4 which has the highest distribution (38.35%) of pore size above 20 µm considered to be favorable for retaining autotrophic denitrifiers. From the above results, it is obvious that the physical properties of the sulfur-based carrier and its ability of denitrification can be influenced significantly by the composition of the carrier.
This study investigated the effects of hydraulic retention time, nitrate loading rate, as well as seed sludge on nitrate removal by using elemental sulfur-based carriers in upflow packed-bed bioreactors. The results showed that nitrate removal efficiency improved by 28 % with increasing hydraulic retention time from 1 h to 4 h. The nitrate removal rate achieved 84 ± 1% at a loading rate of 0.20−0.40 kgNO3⁻-N/m³/d and decreased by 54 % after triggering a loading rate of 1.20 kgNO3⁻-N/m³/d. Besides, nitrite accumulation was noticeable, with nitrite effluent concentration being 15.9–16.6 mgNO2⁻-N/L, as operating at nitrate loading over 0.80 kgNO3⁻-N/m³/d. Interestingly, after enriching seed activated sludge, the sum proportion of Thiobacillus and Sulfurimonas (well-known denitrifying bacteria) increased from 17.1 to 18.4% to 55.4–56.3 %, which improved nitrate removal efficiency to 90 ± 3%. Overall, the high nitrate removal rate of 0.36 kgNO3⁻-N/m³/d demonstrated that elemental sulfur-based carrier is a powerful candidate to apply for autotrophic denitrification.
Efficient denitrifying bacteria isolated from sediments were fixed with ceramsite and were used to simulate the release of the carbon source in nitrate-rich landscape water. Meanwhile, advantages of denitrifying bacteria immobilized with ceramsite on nitrate-N removal during preservation at room temperature were also addressed by comparing with sponge. The results demonstrated that the sediment could effectively release the carbon source in the simulated experiments. The immobilization of denitrifying bacteria with ceramsite was an effective method for nitrate-N removal from landscape water. After 2 days denitrification, the removal rate of nitrate-N reached 98.1% and the removal rate of total nitrogen appeared to be 91.5%. The concentrations of nitrate-N decreased from 16.72 mg/L to 0.19 mg/L after 10 days denitrification, and the removal rate was about 98.8%. The concentration of total nitrogen decreased from 17.89 mg/L to 0.95 mg/L after 10 days denitrification, and the removal rate was about 94.7%. Denitrifying bacteria immobilized with ceramsite kept higher activities after 60 days preservation at room temperature. The concentration of nitrate-N decreased from 37.28 mg/L to 0.08 mg/L, and the removal reached 99.8%. The results indicated that denitrifying bacteria immobilized with ceramsite could be effective method to remove the nitrate-N in the waste water, and could be further used in waste water treatment in the future.
