Date

2017

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Environmental Engineering

First Adviser

SenGupta, Arup K.

Other advisers/committee members

Brown, Derick G.; Jellison, Kristen L.; Fox, John T.; Watkins, Todd A.; Roberts, James E.

Abstract

Millions of people across the Indian subcontinent are at risk of chronic exposure to arsenic and fluoride in aquifers with excess TDS (>500 mg/L). Hybrid anion exchange resins with nanoparticles of zirconium oxide (HAIX-NanoZr) were created for effective fluoride removal; zirconium oxide selectively bound fluoride, silica, and phosphate. The zeta potential of HAIX-NanoZr was directly correlated to the fluoride removal capacity. Thus, to increase fluoride capacity and achieve partial desalination concurrently, a weak acid cation (WAC) exchange pretreatment was used to lower alkalinity, hardness, pH, and TDS. Consistent partial desalination (~50%) occurred in proportion to influent alkalinity and hardness. With regular acid conditioning of WAC, the fluoride capacity of HAIX-NanoZr increased 10x, 300 bed volumes (BVs) to 3500 BVs. Upon regeneration with 2% NaOH, >95% of capacity was restored; fluoride treatment was identical over three consecutive cycles with water from a fluoride-contaminated well (Nakuru, Kenya). Passive pH adjustment (pH 6.5-8.5) of HAIX-NanoZr effluent was achieved with WAC-Na form and/or dolomite.Pilot-scale production of HAIX-NanoZr was researched and developed in Kolkata; analysis of zirconium content and fluoride capacity were performed at Lehigh. Modifications to washing/drying steps were critical for high fluoride capacity. Concurrently, Drinkwell (WIST, Inc., USA; WIST Systems Pvt. Ltd., India) was founded to scale-up HAIX-NanoZr across the Indian subcontinent. An exclusive licensing agreement for HAIX-NanoZr to an Indian partner company was created to pursue Indian government grants and tenders for arsenic and fluoride treatment. Under government supervision, HAIX-NanoZr was piloted for fluoride/TDS removal in Andhra Pradesh, Assam, Madhya Pradesh, Odisha, and West Bengal; HAIX-NanoFe/Zr was piloted for arsenic removal in Chhattisgarh, Jharkhand, and West Bengal. After initial lessons, treatment systems have met Indian drinking water standards.A cash flow model of HAIX-Nano as an entrepreneur-owned small business was developed and Monte Carlo analysis was performed. After being capitalized, self-sustaining operations with market-rate wages were achievable under a range of scenarios. But, capitalization will be difficult for most operations. Price of water and number of customers (TR = P x Q) were the most sensitive input variables, i.e., the most critical factor to financially sustainable water treatment was good business practices.

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