Armor-Structured Interconnected-Porous Membranes for Corrosion-Resistant and Highly Permeable Waste Ammonium Resource Recycling

Abstract

Ammonium recovery from wastewater by gas-permeable membranes is promising but suffers from the tradeoff between membrane stability and permeability under harsh operating conditions. Chemical-resistant membranes display modest permeability due to the poor solubility and processibility; chemically active membranes are easier to be endowed with better permeability however hinder by instability. To resolve such a problem, we cleverly design a novel membrane configuration via one-step solution-electrospinning, with the chemical-active component (low-strength fluorine polymer) as the inner skeleton to construct interconnected porous structures and the chemical-resistant component (high-strength fluorine polymer) as the outer armor to serve as a protective layer. Due to the significantly enhanced mass transfer coefficient, the interconnected-porous armor-structured membrane exhibited much higher permeability for NH4 +-N recovery, which was 1.4 and 5 times that of the traditional PTFE membrane and PP membrane, respectively. Through long-term intermittent and consecutive experiments, the reusability and durability of the armor-structured nanofibrous membrane were verified. When treating actual hoggery wastewater with complicated water quality, the armor-structured nanofibrous membrane also displayed robust stable performance with excellent antiwettability. The mechanisms of membrane formation, corrosion resistance, and mass transfer were discussed in detail.

Bubble Turbulent Gas-Permeable Membrane for Ammonia Recovery from Swine Wastewater: Mass Transfer Enhancement and Antifouling Mechanisms

“…After seven batches of operation, the element content on the surface of the BT-GM was consistent with that of the original membrane (Figure h). In particular, the oxygen element content on the surface of the membrane did not change significantly after operation, confirming the excellent corrosion resistance of the gas-permeable nanofibrous membrane used in this process . Compared with the pristine membrane, the O content on the membrane surface without turbulence increased 13 times and a new component N appeared, indicating the presence of nitrogen-containing organic pollutants on the membrane surface.…”

“…In particular, the oxygen element content on the surface of the membrane did not change significantly after operation, confirming the excellent corrosion resistance of the gaspermeable nanofibrous membrane used in this process. 30 Compared with the pristine membrane, the O content on the membrane surface without turbulence increased 13 times and a new component N appeared, indicating the presence of nitrogen-containing organic pollutants on the membrane surface. In addition, the conventional GM process showed an F/C ratio of 0.51, which was 52% lower than that of BT-GM, indicating that the membrane surface was covered with pollutants.…”

“…A corrosion-resistant nanofibrous gas-permeable membrane with an armored sheath and interconnected pores was used for ammonium recovery, and its stable chemical structure was demonstrated in preliminary work. 30 The hydrophobic gas-permeable membrane was used as a medium to separate high-concentration ammonium-containing wastewater and the acidic solution. The effective contact area of the test membrane with an average pore size of 1.45 μm was 12.6 cm 2 .…”

“…28,29 The working principle involves managing the ammonia partial pressure difference between the two sides of a hydrophobic membrane with the assistance of alkali regulation to facilitate ammonia transmembrane absorption. 30 Recently, several novel gas-permeable membrane coupling synergistic technologies have been investigated, including dialysis-osmotic distillation, 31,32 electrochemical coupled membrane stripping, 33,34 and thermal-membrane distillation. 35 Recovering ammonium from wastewater to draw support from a gas-permeable membrane (GM) not only bypasses the time-consuming nitrogenous species removal through nitrification/denitrification but also reduces the reliance on energy-intensive resynthesis via the Haber−Bosch process.…”

“…35 Recovering ammonium from wastewater to draw support from a gas-permeable membrane (GM) not only bypasses the time-consuming nitrogenous species removal through nitrification/denitrification but also reduces the reliance on energy-intensive resynthesis via the Haber−Bosch process. 30 Although the gas-permeable membrane process has made breakthrough progress in ammonium resource recovery, there are still challenges to its large-scale industrial implementation. On the one hand, ammonia molecules are bound by hydration in conventional gas-permeable membrane systems, slowing their desorption from the solution phase.…”