Pressure-driven Membrane Nutrient Recovery from Wastewater
Restricted (Penn State Only)
- Author:
- Anari, Zahra
- Graduate Program:
- Chemical Engineering (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 16, 2024
- Committee Members:
- Andrew Zydney, Chair & Dissertation Advisor
Rachel Brennan, Outside Unit & Field Member
Stephanie Velegol, Major Field Member
Christopher Arges, Major Field Member
Robert Rioux, Professor in Charge/Director of Graduate Studies - Keywords:
- Nanofiltration
Reverse Osmosis
Nutrient Recovery
Wastewater Treatment
Struvite - Abstract:
- This dissertation investigates the use of pressure-driven membranes for nutrient recovery from wastewater. The focus is on the recovery of nitrogen and phosphorus, which are essential nutrients for agriculture and industry, and are commonly found in industrial and municipal wastewater. The rising price of nitrogenous fertilizers and the depletion of phosphorus reserves have led to a growing interest in sustainable approaches to recover and reuse these nutrients from wastewater. The study evaluates the performance of commercial nanofiltration (NF) and reverse osmosis (RO) membranes with different polymer chemistry and molecular weight cut-offs (MWCO) for maximum nutrient recovery efficiency. The results show that the Alfa NF membrane (PA-TFC, 300 Da MWCO) has the highest concentration factor for phosphorus (P) recovery from synthetic wastewater, while the BW30LE (PA-TFC, 100 Da), Synder (PA-TFC, 100-250 Da), and NF90 (PA-TFC, 200-400 Da) NF membranes achieved a high concentration factor for nitrogen (N) recovery. In an effort to apply these results to real wastewater nutrient recovery, we investigated the recovery of ammonium and organic carbon as organic liquid nitrogen fertilizer from poultry wastewater. The use of Synder and NF90 membranes resulted in severe fouling and membrane degradation due to high concentrations of complex poultry wastewater. Peracetic acid (PAA) treatment was used to reduce fouling and improve membrane performance. We also investigated the recovery of P from municipal wastewater as struvite using an NF preconcentration step followed by electrochemical struvite recovery. Alfa membrane showed a severe inorganic fouling using real wastewater sources with high phosphate concentration. The use of a more hydrophobic NF membrane (polyethersulfone) resulted in a seven-fold increase in wastewater concentration, leading to a faster rate of phosphate precipitation and lower electrochemical energy consumption, magnesium electrode loss, and electrochemical operating costs. However, the combined membrane-electrochemical system operating cost was increased, highlighting the need for further optimization of membrane conditions. Despite the increased total operating cost, the gained struvite profit increased from approximately 245 to 1162 $/m3, demonstrating the potential for increased resource recovery through the utilization of membrane preconcentration in electrochemical struvite precipitation processes. This dissertation contributes valuable insights to the field of wastewater treatment by exploring the potential of using pressure-driven membranes to recover nutrients from wastewater. Specifically, the study sheds light on the importance of selecting an appropriate membrane polymer chemistry based on the composition of the real wastewater being treated. The results of the study demonstrate that nanofiltration (NF) membranes with varying molecular weight cut-offs (MWCOs) and polymer chemistries can effectively recover both nitrogen and phosphorus from wastewater. However, the study also identified the need for further optimization to address issues such as fouling and scaling of the membrane systems. This finding underscores the importance of controlling the pH of the wastewater and applying proper pretreatment measures to prevent fouling and scaling of the membrane nutrient preconcentration systems. Overall, this dissertation contributes to the development of more efficient and sustainable methods for nutrient recovery from wastewater, which can have important implications for environmental and public health.