Removing nutrients, such as nitrogen and phosphorus is an increasingly important objective of wastewater treatment to reduce the impacts of nutrient pollution on waterways. Current technologies to remove these nutrients can be capital intensive, require dangerous chemical inputs and have high operational costs. Our company, Algal Scientific, has developed an innovative nutrient treatment system that sequesters nitrogen and phosphorus from the wastewater into the biomass of specially-selected algal species. This technology differs from the current nutrient treatment technologies that rely on bacterial-mediated conversion of soluble nitrogen into nitrogen gas and a separate chemical and/or biological precipitation of phosphorus. Algal Scientific's algae-based process not only reduces capital and operating costs but also provides net environmental benefits including reduced energy consumption and the production of a high-value algal biomass that can be converted into useful products such as bioenergy and biofertilizer. The main objective of the proposed research is to determine whether an anaerobic pre-treatment step can condition certain waste streams to help optimize Algal Scientific's current algae-based treatment process. The proposed research utilizes both flask-scale and benchtop-scale experiments to determine which operating parameters of the anaerobic pre-treatment process result in the best nutrient removal performance by Algal Scientific's established downstream algae-based process. Algal Scientific expects these experiments to demonstrate an increase in the availability of nitrogen and phosphorus for algal sequestration, which would allow the company to decrease the water residence time of its entire wastewater treatment process. This improvement alone would substantially decrease operating and capital costs and allow Algal Scientific to remove nutrient more cost-effectively. During Phase II, Algal Scientific will scale up the anaerobic pre-treatment process developed in Phase I to a flow rate capable of supplying pre-treated wastewater effluent to our companys pilot and demonstration-scale operations. Algal Scientific already has one onsite pilot plant (100-liters bioreactors) operating with its current technology, and it expects to have a 50,000 liter per day demonstration-scale operation installed by the end of 2010, and its first commercial-scale operation (> 1 million liters per day) installed by the end of 2012. If the Phase II research demonstrates that our proposed pre-treatment process provides a net cost-savings, Algal Scientific then will integrate the process into its commercial scale design. Although wastewater nutrient regulations will drive the implementation of its system across the country, Algal Scientific expects to help customers achieve compliance and at the same time save money, reduce energy costs, and produce a valuable renewable biomass byproduct. Summary/Accomplishments (Outputs/Outcomes): A set of four anaerobic reactors were used to test the effects of key operating parameters in converting the nitrogen and phosphorus in the wastewater into forms that algae can utilize. For example, most algae can only utilize nitrogen in the form of nitrate (NO3) and ammonia (NH3) and phosphorus in the form of phosphate (PO4). Anaerobic digestion by bacteria helps to hydrolyze organically bound nitrogen and phosphorus into those forms that algae can use. The anaerobic reactors were controlled automatically with wastewater being added on a semi-continuous basis with peristaltic pumps in order to achieve the desired hydraulic retention times (i.e., how long the wastewater remains within the reactor). The wastewater that Algal Scientific tested was from a local corn milling facility and was characterized by very high concentrations of solids (>5%), chemical oxygen demand (>100,000 mg/L), total phosphorus (>1,000 mg/L) and total nitrogen (>1,500 mg/L). To simulate the strength of wastewaters that their algae system would typically be treating, Algal Scientific diluted the wastewater to between 5 and 50% of the original sample. After an initial acclimation period, the company started testing the effluent from the anaerobic reactors with the objective of maximizing the ratio of available nitrogen (i.e., NH3/total nitrogen) and phosphorus (PO4/total phosphorus). As expected, the hydraulic residence time was positively correlated with the amount of available nitrogen and phosphorus produced. After several weeks of data with the reactors running at steady-state conditions, Algal Scientific was able to determine an optimal hydraulic residence time that produced the most available nitrogen and phosphorus in the shortest period of time. The second major objective of the research was to determine whether the increase in available nitrogen and phosphorus would increase the nutrient removal rate by the algae in the downstream algae reactors. Algal Scientific performed a series of flask-scale experiments using effluent from the anaerobic reactors. The flask-scale experiments had mixed results, depending on the initial concentration of the wastewater that was anaerobically digested. In general, the effect of anaerobic pre-treatment increased the nutrient removal performance by the algae when the original concentration of the wastewater was highest. Algal Scientific followed up the flask-scale experiments with larger 2-liter bioreactors and the results largely confirmed that the positive effect of the anaerobic treatment on nutrient removal efficiency was highest with the highest original wastewater concentration. Conclusions: Algal Scientific's Phase I research effectively demonstrated two major concepts. First, an anaerobic pre-treatment step was highly effective in increasing the availability of nitrogen and phosphorus in wastewater. In some cases, the ratio of available nitrogen and phosphorus increased by several fold. Second, the research demonstrated that the nitrogen and phosphorus removal rate by the algae following anaerobic pretreatment was higher than without treatment. Again, under certain conditions, the phosphorus removal rate increased by more than 50%. Unexpectedly, the company also observed that certain algae species grew substantially better relative to other species when grown on the anaerobically treated wastewater. This opens the possibility for generating very high-value algal co-products from large agribusiness process water streams. Publications and Commercialization Algal Scientific already has taken steps to submit provisional patent claims based on the concepts that were developed during this research. Besides patent applications, the company does not expect to produce any other peer-review publications. Algal Scientific is an early-stage start up company and currently is arranging for additional demonstrations and pilots to demonstrate its technology. Based on the success of obtaining the funding for Phase II, the company would expect to at least scale up the anaerobic treatment process described in this research up to the scale that could pretreat most, if not all, of the wastewater entering the 2,000 gallon per day algae demonstration systems. From an economic standpoint, presuming that the technology scales up, Algal Scientific would need to consider whether the extra capital and operating expenses for the anaerobic process results in a more cost-effective treatment system by increasing the rate that the algae systems could process the anaerobically treated wastewater.
