Hybrid ferrihydrite-MF/UF membrane filtration for the simultaneous removal of dissolved organic matter and phosphate

Abstract

Dissolved organic matter (DOM) and phosphorus promote microbial regrowth in water distribution networks. Ferrihydrite (Fh) has a high adsorption affinity with DOM and phosphate. Hence, a lab-scale unit of the hybrid Fh-MF/UF membrane filtration system was used to evaluate membrane fouling and the removal efficiency of DOM and phosphate. Suwannee River natural organic matter (SRNOM) was used as a surrogate for DOM in natural water. The Fh-membrane system demonstrated removal rates of dissolved organic carbon (DOC), UV254 and phosphate up to 50%, 80% and 90%, respectively, at the Fh dose of 17.5 mg/L. The effect of phosphate on the removal of DOM was different without or with the addition of Fh; namely, phosphate increased the DOM removal without Fh by interacting with the UF membrane made of regenerated cellulose (RC), but phosphate decreased the DOM removal by Fh due to the strong affinity of phosphate with Fh. Size exclusion chromatography revealed that phosphate mainly competed against smaller DOM molecules for Fh adsorption sites. Although the addition of Fh caused only a moderate flux decline with the RC membranes, the deposition of positively charged Fh on the surface of a negatively charged high-flux membrane, i.e., polyethersulfone (PES), caused a rapid decline of the permeation flux.

Removal of precursors of disinfection byproducts by hybrid ferrihydrite adsorption-membrane filtration process

“…(2) DOM removal by the hybrid MF processes Calculated hydraulic contact time with adsorbents is shown in Table 3. According to the Yang et al (2014) 25) , the adsorption of DOM onto FH reached equilibrium within 5 min, which is within the range of calculated hydraulic contact times in this study.…”

“…The 2-line FH was synthesized following the method proposed by Leone et al (2001) 24) and Yang et al (2012) 25) . The stock solution of FH was sonicated at 80 W for 10 min (Branson Sonifer 450, Branson, USA) before storage.…”

“…(3) Hybrid FH+MF and PAC+MF processes The lab-scale MF system are described in detail in our previous publications 25,29) . A hydrophilic PVDF membrane with a nominal pore size of 0.10 μm and an effective surface area of 13.4 cm 2 (VVLP09050, Millipore) was used to ensure adsorbent separation.…”

Release of dissolved organic matter from melting ice

“…UV-254 is mainly caused by electro-rich sites, such as aromatic functional groups and double-bonded C groups in the DOM molecule, and is generally reflects the aromatic C@C contents [32].…”

Facile Synthesis of Struvite from Municipal Wastewater Using Pre-Treated Magnesite

“…In the quest to manage high levels of phosphates and nitrates and the endeavours to curtail its impacts, researchers have developed a number of technologies for the removal of the said pollutants. The technologies involve the use of adsorbents [7], precipitants [8], filters [9], phytoremediation [10,11], and ion exchange resins [12] to remove high levels of phosphates. Adsorption is a widely used technology for the removal of pollutants from water but it challenge is limited efficiency in concentrated solution and the requirement of the adsorbent to be regenerated frequently.…”