Progress 07/01/23 to 02/29/24

Outputs
Target Audience:Our audience is engineers that operate wastewater treatment plants. The individual that requires the data from our system is typically either an engineer involved in process optimization or a sales team member looking to select the correct treatment process or chemicals for a customer. These individuals need specific, rapid data to make a decision. In our experience, they do not have the same level of concern regarding accuracy and specificity that the laboratory would demand. They are interested in understanding how their process is working and where it is headed. Our customers need data more quickly; shipping to a laboratory is time lost in a time critical process. It is important to note that our initial customers are not laboratory scientists or technicians. The laboratory does not have a need for our system, as their current approach provides the data they desire. Speed and ease-of-use are secondary concerns. We have learned this lesson through many potential customer conversations: the laboratory finds the technology "cool" but does not see a need to change anything without external pressure. Therefore, the economic buyer is the individual that needs the data to make a decision--not the individual generating the data. These customers are process engineers and plant managers. They need to make decisions quickly to protect assets and to boost profits. They consume the data and are willing to pay to get accurate results without waiting for the laboratory to clear the testing queue. The technology proposed in this application addresses energy efficiency and renewable energy in the wastewater treatment process. New methods for wastewater treatment optimize the generation of biogas that is used to generate electricity, in addition to being more energy efficient when removing nitrogen. These new methods require improved process monitoring and control technologies, including nitrogen analysis such as proposed here. These advancements make our audience,as a whole, the public, who have a general interest in clean water and energy efficient operations. Changes/Problems:The primary challenge we faced during Phase I was our ability to scale production of reagents needed for continuous analysis. Not only did we need materials for this project, but also for commercial operation. We improved the production of ammonia reagents by preparing mixtures from powder instead of dilutions from stock solutions. This change allows for the reagents to be prepared with a long-shelf life; water needs to be added only when the solutions are introduced. For hydroxylamine, the internal standard uses heavy (deuterium) water. Heavy water is relatively expensive, but keeping a small stock on-hand left us at the mercy of inventory and shipping delays. These supply constraints can be addressed by ordering larger quantities to have more stock in-house. The major limitation was the production of gold nanoparticles. A single, 12-ml batch of concentrated gold nanoparticles requires 2-3 hours. With multiple in-line systems operating, our consumption was approaching 50-ml per day. We are in the process of scaling production with more automation and improved equipment. The production process can be faster, but only marginally (1.5 hours). We have added more equipment, which allows us to run multiple batches simultaneously. These improvements will continue throughout the Phase II period, and we anticipate eliminating supply constraints in the next couple months. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Under this multiphase SBIR project, OndaVia proposed to demonstrate a prototype in-line analyzer for hydroxylamine and ammonia in wastewater treatment processes. If successful, this device will have a significant impact on the quality and security of our wastewater treatment system. Not only will we better monitor nitrogen pollution, but we will also be able to monitor our drinking water, wastewater output, surface water pollution from point sources, and liquid food sources for contamination. An automated system is also useful to detect and identify non-point-source run-off, which enables better monitoring, and subsequent optimization, of nitrogen and water use. Such an approach would be disruptive with respect to current technologies, leading to a safer, cleaner water supply. The Phase I effort was designed to demonstrate the feasibility of our approach. Our goal was ammonia measurements with a 100-ppb limit of detection (LOD) and hydroxylamine analysis with a 20-ppb LOD. Here, LOD is defined as three times the noise on a blank sample (3σ). We achieved both results, with 18.7-ppb and 15.0-ppb LODs, respectively. Our results surpassed our Phase I goals; and we believe they can be improved further in the Phase II effort. The system assembled for the feasibility project was designed for rapid modification. This rail-mounted system is shown in Figure 3. This design included four syringe pumps: sample delivery and preparation, ammonia reagent delivery, hydroxylamine analysis, and pH. The pH pump is not required for this analysis, but was added to test our ability to handle a fourth pump and to test an additional measurement method. Ammonia analysis includes a heated reaction. The heater block for ammonia analysis is an aluminum unit with a glass reaction vial, an overtemperature safety switch, a thermocouple, and two 24-V, 50-W heater elements. These elements are capable of raising the temperature to 50°C within a few minutes, and easily maintain a temperature ±1°C using PID control logic in the Cortex-M4F-based microcontroller. The microcontroller also controls the syringe pumps, the pH circuit, and an LCD display (not shown). Hydroxylamine requires two mixing vessels (not shown above). These 3D printed vessels hold glass vials and have two inlets for 1/16" PEEK tubing. Future editions will include sensing electronics to detect system faults. System failures that leave the vessels in an unkown state--full, for example--can lead to overflows on restart. Knowing the current level would be useful for reliability. Similar improvements are targeted for the heated reation vessel. Automated hydroxylamine analysis We approached hydroxylamine analysis with two goals: first, demonstrate automated analysis down to 100-ppb; and second, determine the limit of detection in real-world samples. The first goal was driven by our proposed Phase I objectives. This second goal was enabled by our obtaining real-world samples from partners, and not envisioned in the original Phase I proposal. We started hydroxylamine operation in October with a 250-ppb standard. The system ran stabily with results in an expected range for a few days. We ran into reagent manufacturing constraints, and had to stop operation. When reagents were available, we restarted the system and varied the sample concentration. There is some hysteresis and overshoot when switching sample concentration, but when allowed to operate within a narrow band, system performance meets our requirements. Notably, a 100-ppb standard measured 101.9±7.6-ppb over sixty samples taken hourly. Using the EPA method for calculating minimum detection limit (MDL), this corresponds to 18.2-ppb. Our MDL also exceeds the Phase I objective. Automated ammonia analysis As with our hydroxylamine testing, we ran into system errors and reagent limitations that preventing running ammonia analysis continuously for more than a few days. When operating, the results were as expected and within target ranges. At our target LOD for ammonia (100-ppb), the result over 39 samples was 90.0±15.7-ppb. Using the time series data at 0-ppb near the end of the continuous run, we find our LOD is 18.7-ppb, well below the 100-ppb target in the Phase I effort.

Publications