Performing Department
Chemical Engineering
Non Technical Summary
In response to the fast-growing global population and increasing demand for animal protein, aquaculture is the fastest-growing animal food production sector worldwide. With growing competition for natural resources (land, water, etc.) among all production sectors, the intensification of aquaculture systems has emerged as a promising pathway for increasing aquaculture production. Accompanying the aquaculture intensification is the increased demand for feed and increased waste production. On the one hand, aquafeed is recognized as the critical factor limiting the aquaculture industry's growth. On the other hand, aquatic waste is often discharged into the environment, causing eutrophication and threatening the sustainability of local ecosystems. Therefore, sustained intensification of aquaculture production must be coupled with a sufficient supply of sustainable nutrients (feed) and efficient waste management.This project aims to develop and validate a novel, sustainable and profitable waste-to-feed (W2F) biotechnology, which solves the two problems mentioned above (i.e., limited aquafeed and increasing waste) with a single solution. The proposed W2F biotechnology integrates the commercially proven anaerobic digestion (AD) with a recently patented circulating coculture biofilm photobioreactor (CCBP) to convert aquaculture waste into single cell protein (SCP) as aquafeed supplements while producing treated clean water and fertilizer. The waste-derived SCP's efficacy as a nutrient source will be evaluated on Pacific white shrimp. The treated clean water will be tested to satisfy the EPA standards on total nitrogen (TN) and total phosphorus (TP) concentrations.
Animal Health Component
10%
Research Effort Categories
Basic
100%
Applied
0%
Developmental
0%
Goals / Objectives
Through the development and validation of a novel, sustainable and profitable waste-to-feed (W2F) biotechnology, we aim to help develop a circular aquaculture industry that not only helps feed the increasing global population but also significantly improves the industry's sustainability. The proposed W2F biotechnology integrates the commercially proven anaerobic digestion (AD) with a recently patented circulating coculture biofilm photobioreactor (CCBP) to convert aquaculture waste into single cell protein (SCP) as aquafeed supplements, treated clean water, and fertilizer. To develop and validate this W2F technology, we propose the following five specific objectives: (1) AD of fish sludge and food waste to produce biogas and nutrient-rich AD effluent; (2) develop a bench prototypeof the patented CCBP that converts biogas and AD effluent into SCP; (3) demonstration of continuous and stable SCP production using CCBP; (4) assessment of the efficacy of SCP as a nutrient source for shrimp; (5) assessing the technical and economic feasibility and sustainability of the proposed W2F biotechnology.
Project Methods
This trans-disciplinaryproject requires a broad range of scientific research activities that coverdifferent fields. As a result, we describe the involvedmethods corresponding to each objective.Objective 1: Anaerobic digestion of fish sludge and food waste to produce biogas and nutrient-rich AD effluentThe elemental analysis (C, H, N, and C/N ratio) and PSC of the waste samples will be performed at the AU Center for Bioenergy and Bioproducts following established protocols. For both analyses, 10 - 12 samples will be analyzed to determine the mean and standard deviations of all metrics for FS and FW samples. Mixtures of different FS/FW ratios will be prepared to obtain three levels of C/N ratio (15, 20, 25) and three levels of PCS (8%, 10%, 12%). Fishery wastewater will be used for feed mixtures dilution to control the C/N ratio and PSC independently. A full factorial design of FS/FW ratio and PSC results in 9 conditions to be examined. These comparative experiments will be conducted in one-gallon glass jars (covered with aluminum foil to block lights) with triplicates. AD process will be initiated by adding the activated sludge provided by CWW in Georgia, which has a commercial mesophilic AD installed. Biogas production volume will be measured by gas syringe (adjusted by pressure) till jar pressure lowers to 1 atmospheric pressure. The experiment will last up to 4 weeks or until vessel pressure no longer changes (i.e., no biogas generated from any jar). The AD performance metrics to be used are listed in Table 2 (of the submitted proposal). The primary metrics are biogas yield and productivity.The AD system will be monitored and recorded every three to five days based on the results obtained in Task 1.1, using the same set of metrics as listed in Table 2 (of the submitted proposal). All performance metrics will be determined batch-wise (cumulative for yield and average for the rest) for 3-4 batches to determine the metrics' mean and standard deviation. The robustness of the system will be evaluated in terms of the variability (e.g., minimum, maximum, standard deviation) of the performance metrics and the number of failures during the operation, if any.Objective 2. Construction of a scale-up CCBP with smart remote monitoringWe have developed a proof-of-concept 68 L lab-scale prototype of CCBP, and successfully validated its performance using artificial light and synthetic biogas. The development of the benchtop CCBP will follow the established process and methods that we have developed.In prior research, we have pioneered the applications of IoT devices for process monitoring, and developed protocols, hardware, and software for data acquisition, transmission, and storage systems for various IoT sensors.In this objective, following the established protocols we have published, we will deploy additional IoT devices and develop spectrum-based soft sensors to achieve real-time sensing/monitoring of the CCBP.Objective 3. Stable single-cell protein production using CCBPThe bentch-top CCBP will be activated following our proof-of-concept CCBP startup protocol. Once the CCBP operation reaches a stable condition, its performance will be assessed quantitatively. Gas and liquid samples will be taken twice daily (8 am and 8 pm) to determine the effect of diurnal changes, as there will not be photosynthesis during the dark period. Through gas phase composition and liquid phase (inorganic and organic N, P) measurements, we will quantify the baseline CCBP performance using metrics defined in Table 4 (of the submitted proposal). Following our established protocol, the harvested M-M coculture biomass will be subject to composition analysis to determine the protein, carbohydrate, lipid, and ash content.Objective4Assess the efficacy of the produced SCP as a nutrient source for shrimp.To assess the nutrient profiles and the variability of the CCBP-produced SCP, starting in year 2, coculture biomass samples will be collected intermittently (4-10 per year) and pooled together as needed to obtain quantities suitable for biochemical analysis. The collected samples will be dried and then analyzed for proximate composition as well as amino acid and fatty acid profiles, as well as heavy metal contents. The analysis will be conducted at the University of Missouri Agricultural Experiment Station Chemical Laboratories (Columbia, MO, USA) following standard practices. It will include analysis for proximate composition (protein, lipid, fat, fiber, and ash) for all samples and then for representative samples, amino acid, and fatty acid profiles, as well as pepsin digestibility.To assess the digestibility of the SCP, the test diets will be marked with 1% chromic oxide with the 70:30 replacement strategy following the established protocol. Dry matter, crude protein, and total energy will be determined for the fecal, diet, and ingredient samples according to established procedures.72 Finally, apparent digestibility coefficients (ADC) of the dry matter, protein, amino acids, and energy for each diet will be calculated.To evaluate nutrient availability, we will conduct a series of growth trials. The growth trials will be conducted at the E. W. Shell Fisheries Center following established protocols in the Davis lab73 and run under low salinity conditions (4-8 ppt). At the concluding growth trial, growth, survival, feed conversion, and nutrient retention will be determined.Objective 5: Comprehensive and integrated techno-economic analysis - life cycle assessmentThe proposed W2F technology will be evaluated for its technological and economic feasibility and sustainability through an integrated TEA-LCA. In this project, the following techno-sustainability metrics will be used to evaluate the proposed technology:Technical performance: (1) biomass surface area productivity; (2) biomass footprint area productivity; (3) energy consumption per unit biomass production; (4) nutrient recovery rate.Economic sustainability: (1) annualized capital and operating costs, investment, tax, revenue, and profit; (2) net present value (NPV); (3) minimum aquafeed selling price.Environmental sustainability: (1) net energy ratio (NER); (2) global warming potential (GWP); (3) water consumption; (4) waste and pollution generationSocial sustainability: (1) impact on local community FS management; (2) impact on local community water supply; (3) impact on local/regional economy