@bridog I don't think Nitro has happened yet commercially, but that is now the intention. As above they had a grant of approx $1 million USD to work with Energy Systems Group to develop a MABR process to work with anaerobic digester sludge through BIRD. So there were R&D plants running with a commercial R&D partner. This must have come to some sort of natural conclusion where the product is now deemed ready for commercial use. It seems they will be targeting maybe smaller scale plants that require a simple MABR based solution to reach stricter effluent nitrogen removal requirements.
I don't think they will need to do a CR for new products, as these products are essentially still MABR based products with a custom process design depending on the type of supernatant they are going to be treating. Like SUBRE, each plant would be a custom design, and the customer would essentially pay for the parts required to build the system. I don't think Fluence are necessarily manufacturing anything new.
Maybe some of these 1200 anaerobic digesters need this type of supernatant treatment. This also sounds like a higher margin product, so if Fluence is successful at selling any of these solutions, it should be a decent financial boost.
Here's a Ronen Shechter presentation from 2019.
Purpose: INTRODUCTION The stream from dewatering of digested sludge, referred to as supernatant or sidestream throughout this document, is of low volume but high nitrogen load on the water treatment process. Typically, the volume loading will be 1-2% and the nitrogen in the form of ammonia compound will be 15-20%, both relative to wastewater influent to the plant. On one hand this additional ammonia load to the wastewater is significant for design and operation, but on the other it represents an opportunity to remove a significant part of the nitrogen load by treating a side stream. Side stream treatment presents an interesting possibility because of two main reasons: a) the higher concentrations of both influent and effluent for this stream may support higher removal rates; b) the parallel treatment process is independent of the main water treatment process and thus add resilience to plant nutrients removal capacity. In cases, when plant capacity is limited, separate treatment of the side stream is may provide compliance with nutrients requirements.Different processes have been proposed for side stream nutrients removal in recent years, targeting energy minimization by de-ammonification using anammox [1, 2, 3] or resource recovery through chemical precipitation of struvite [4, 5]. It can be generalized that these processes are just starting to be applied, and mostly in larger facilities. However, there are many smaller plants that might be looking for simpler solutions that provide similar benefits. Membrane aerated biofilm reactors (MABR) are known for mainstream simultaneous nitrification and denitrification ([6, 7]). In MABR oxygen for ammonia oxidation is supplied via a permeable, self-respiring membrane, on which an autotrophic nitrifying biofilm can be manipulated to develop, such as by holding a sufficient concentration of MLSS. It has been shown that the oxygen permeation rate in MABR is equivalent to the nitrification rate and varies accordingly, and thus leads to the conclusion that ammonia concentration is limiting the rates. The typical values reported for nitrification rate and oxygen permeation in municipal wastewater treatment are 2-3 g/d/m2 and 10-15 g/d/m2 respectively [6, 7, 8].In this work high rate oxidation of ammonia using a MABR is demonstrated in both lab and pilot scales, treating supernatant at high ammonia concentrations. Furthermore, control on nitritation over nitrification is demonstrated as additional basis for higher rates and lower organic carbon requirements for eventual total nitrogen (TN) removal.
MATERIALS AND METHODS a. Lab scale MABR A flat sheet MABR with a volume of 0.5 l and membrane surface area of 0.06 m2, as shown in figure 1, was used for the lab stage of this work. In this lab scale MABR water flows between two membranes which are exposed to ambient air flowing on their outer surfaces. The reactor was inoculated with sludge from the RAS stream of a local WWTP then operated in a biofilm only mode and fed with a synthetic solution of an ammonia salt, NaHCO3 for alkalinity, phosphate and trace elements. During testing ammonia concentration was varied in the range 250-800 mgN/l, and hydraulic retention times in the range 3-24 hours. Mixing was provided by circulation at a ratio of 100-200. Ammonia nitrogen, nitrate, nitrite, pH, DO and ORP were monitored regularly by sampling and analysis. For the biofilm population analyses samples were taken for next generation sequencing analysis. b. Pilot scale MABR The pilot scale unit shown in figure 2, comprising 2 spirally wound modules in two 4 m3 tanks fed in parallel, was operated in a WWTP on the Carmel Coast in Israel. Supernatant from the aerobic sludge stabilization process was fed to the system at 36 m3/d and ammonia concentration of about 250 mgN/l. The tanks were mixed periodically every 15 minutes for 20 seconds through coarse bubble diffusers installed beneath the modules.
RESULTS AND DISCUSSION a. Lab scale MABR Nitrification rate increased with the load and consequent effluent ammonia concentration, up to an average of more than 6 g/d/m2 at a concentration of about 85-90 mg/l, above which it did not increase anymore and indicated that the oxygen was limiting the rate at these conditions, as seen in the blue markers in figure 3.In order to validate the above conclusion, air was enriched with oxygen up to 29% at the inlet, resulting in 24% at the outlet or about 26.5% in average as the driving force for diffusion through the membrane. As a result, the ammonia removal rate increased up to more than 10 g/d/m2 at about 250 mg/l NH4-N, as seen in the red markers in figure 3, which validated it was indeed limiting the rate working with air.Throughout the above conditions nitrate and nitrite concentrations distribution in the effluent varied between 40-60% and oxygen concentration was less than 0.05 mg/l. At the higher influent ammonia concentrations of 800 mgN/l, still treating to about 100 mgN/l nitrate and nitrite concentrations distribution in the effluent changed significantly to mostly nitrite (about 90%) as shown in figure 4. This result followed an attempt to inhibit NOB by maintaining a high nitrite concentration until it was self-sustained.The biofilm population analysis in figure 5 shows that more than 40% of the population was AOB and NOB similarly distributed, whereas the reactor fluid was predominantly AOB. b. Pilot scale MABR The pilot system was initially operated in continuation to treating wastewater with only a biofilm and yielded the nitrification rate results shown on the left side of figure 6, which were significantly lower than lab results. Following chemical cleaning, noted in green on figure 6, the rate increased to more than 6 g/d/m2 as shown on the right side of figure 6. It was hypothesized that acclimation will facilitate the development of a customized biofilm quicker. Results show that this action yielded rate results that agree with the lab testing for similar conditions with air.Further testing with the pilot unit are planned in another facility with anaerobic sludge treatment in order to duplicate lab results for AOB inhibition.
CONCLUSIONS - High rate ammonia oxidation using MABR was validated in both lab and pilot scales. - Maximum ammonia removal rates were 6.0-7.0 gN/d/m2 using air as the process gas, equivalent to oxygen permeation of 20-22 g/d/m2. - Oxygen from air is limiting the nitrification rate at ammonia concentrations above 85-90 mgN/l with the tested membrane. - NOB inhibition to obtain up to 90% nitrite was sustainable at high effluent nitrite concentrations of up to 600 mg/l.
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