Executive Summary : | Reverse Osmosis (RO) water processing generates reject at a rate 5 times of the treated water. Being rich in inorganic nutrients and minerals, reject water is a potential environmental contaminant. The nutrient rich RO reject can serve as potential growth media for mass scale algae cultivation. By doing so, safe discharge and recycling of reject from RO plants can be ensured with simultaneous production of metabolite rich algal biomass. Some of the key high value metabolites (HVMs) present in algal biomass are anti-oxidant, phenolic compounds, amino acids, polyunsaturated fatty acids (PUFA) and natural pigments. Further, the algal biomass is an excellent source of biofuel precursors (BfPs). In brief, this project aims to develop an efficient process for RO reject water utilization and recycling with co-production of HVMs and BfPs in a high-density photobioreactor (PBR). With regard to the PBRs, the project shall investigate both the suspended culture and biofilm type PBRs. In the former type, the recently invented flat-panel airlift PBRs and liquid foam-bed PBRs exhibiting high illuminated surface-area-to-volume ratio allows high density algae cultivation along with potential CO2 sequestration. These PBRs offer low-cost, energy-efficient, in-situ harvesting; the harvesting can be further assisted by, e.g., pH assisted auto-settling and fungal palletization, recently patented by our group. In the next phase, attempt shall be made to extract selected HVMs (particularly PUFA, amino acids and pigments) from the produced biomass through microwave assisted thermo-enzymatic processing. The residual biomass will be subject to catalytic hydrothermal processing for recovery of biofuel precursors (BfPs) including bio crude oil, biochar and aqueous products for heavy oil production. The final waste, if any, may be used in anaerobic fermentation for CH4/H2 production. Finally, economic viability of the overall process for mass scale productions shall be determined and further improved employing process integration and modeling tools. Once successful, the process would serve as a role model for efficient utilization of RO reject with coproduction of valued products under biorefinery approach. Subsequent to its successful completion, the technology can be tested at Pilot scale (TRL-5) with industrial partner H2O Mantra Pvt. Ltd., one of the speedily growing startups in water treatment. Apart from meeting the main objective, the proposed work would deliver multifarious advances in the field of RO reject recycling through algal technology and add significant value to the algal biofuel route. The project would look for the efficient dissemination strategy to ensure that the outcomes reach the relevant stakeholders by involving them in the ongoing R&D. Regular feedback shall be sought from the stakeholders, and responded accordingly in further R&D during the project. |
