Author ORCID Identifier
Semester
Fall
Date of Graduation
2024
Document Type
Dissertation
Degree Type
PhD
College
Statler College of Engineering and Mineral Resources
Department
Chemical and Biomedical Engineering
Committee Chair
Oishi Sanyal
Committee Member
Fernando V. Lima
Committee Member
Cerasela Zoica Dinu
Committee Member
Lian-Shin Lin
Committee Member
Konstantinos Sierros
Abstract
Global demand for fertilizer production is expanding substantially to meet the food demand of an increasing world population. Anaerobic digestate (AD) of various centralized wastewater facilities contains substantial amounts of ammonium (NH4+) (300-800 mg/L), potassium (K+) (13-120 mg/L), and phosphorus (P) (30-100 mg/L)- based nutrients. In addition to reducing energy costs and CO2 emissions compared to conventional fertilizing raw material manufacturing, recovering nutrients from these waste streams could help mitigate problems such as eutrophication, which otherwise incurs billions of dollars losses to US economy annually. Apart from nutrients, wastewater streams also contain organic pollutants (TOC) (250-1000 mg/L), whose presence can promote micro-organism growth and reduce the value of the derived fertilizers. The aim of this dissertation is to design nanofiltration membranes to selectively separate nutrients (NH4+, K+) and organics from nutrient-rich resources. The first part of this dissertation focuses on developing polyelectrolyte-based membranes by utilizing layer-by-layer (LbL) dip-coating technique to separate two nutrient products NH4+ and K+ from organics. The second part is aimed at designing a crosslinked polyelectrolyte-membrane platform that allows partitioning of NH4+ and K+ in tunable proportions in two product streams. In the final part, an unconventional direct ink writing (u-DIW) technique is introduced to fabricate polyelectrolyte-based membranes, aiming to minimize solvent usage during membrane manufacturing.
To achieve the goal of separating nutrients (NH4+, K+) and organics, the selective layer of various commercial membranes (NF/UF) were modified via layer-by-layer (LbL) deposition of different alternatively charged polyelectrolytes. This modification involved adjusting various LbL parameters, including polymer types, pH, the addition of salt (NaCl) within polyelectrolytes, polymer cross-linking, etc. Such modifications resulted in membranes with diverse properties and demonstrated a trade-off relation between nutrient passage and nutrient/organic selectivity. The findings from this study indicates that both size and charge of the membrane play a vital role in achieving high nutrient/organic pollutant selectivity.
While the first part of this dissertation focused on separating nutrient and organics, the second part is aimed to partition two nutrients - NH4+ and K+, using a novel membrane surface-modification approach. NH4+ and K+ are two critical fertilizer raw materials and achieving selective separation between them would offer the flexibility to tune the nutrient (N:K) ratio, enabling a final product suitable for a diverse range of fertilizing applications. Separation of NH4+/K+ is intrinsically challenging since the hydrated radii of both NH4+ and K+ are identical (0.33 nm) with a slight difference in hydration energy (~10 KJ/mol) between them. To achieve high NH4+/K+ selectivity, polyelectrolyte surface modification is applied to existing commercial membranes, followed by controlled covalent crosslinking. This dissertation presents a fundamental framework of designing crosslinked polyelectrolyte membranes to achieve selective separation between NH4+ and K+. Furthermore, the critical mechanism associated with this separation is briefly elucidated.
In this dissertation, conventional LbL dip-coating was primarily employed to fabricate polyelectrolyte membranes for nutrient recovery applications. This method has a disadvantage of large solvent (water) usage during membrane fabrication. To address this issue, the last part of this dissertation aims to fabricate polyelectrolyte multilayer (PEM) films using an unconventional direct ink writing (u-DIW) technique, which allows the printing of polyelectrolytes via capillary action, without any assistance of external pressure. Here, PEM films were fabricated by tuning various polyelectrolyte parameters such as molecular weight, deposition time, pH, etc. The critical parameters associated with u-DIW films were compared against traditional dip-coated films and found to be very similar, while the u-DIW requiring ~10X less solvent (water) usage compared to dip-coating for fabricating membranes. The findings from this dissertation indicate that polyelectrolyte films fabricated by using this technique could potentially be applicable to a wide range of water treatment applications, including nutrient recovery and desalination, as well as to biomedical applications such as drug delivery and protein adhesion.
In summary, this dissertation presents a novel strategy of recovering two nutrient ions (NH4+ and K+) from wastewater. The most unique contribution of this dissertation is the development of a novel crosslinked polyelectrolyte-based membrane platform for the separation of same sized monovalent nutrient (NH4+/K+). In addition, the applications of polyelectrolyte multilayer NF membranes were also demonstrated for nutrient/organic separations. Furthermore, a novel strategy for fabricating polyelectrolyte film was shown by utilizing an unconventional direct-ink writing technique, which holds the potential of enabling widespread adoption of LbL in various separation and biomedical applications.
Recommended Citation
Piash, KM Prottoy Shariar, "Novel Membrane Materials for Nutrient Recovery from Nutrient-Rich Resources" (2024). Graduate Theses, Dissertations, and Problem Reports. 12662.
https://researchrepository.wvu.edu/etd/12662
Included in
Environmental Engineering Commons, Membrane Science Commons, Polymer and Organic Materials Commons, Polymer Science Commons, Transport Phenomena Commons