Abstract
Hydrophobic membrane contactors represent a promising solution to the problem of recycling ammoniacal nitrogen (N-NH4) molecules from waste, water or wastewater resources. The process has been shown to work best with wastewater streams that present high N-NH4 concentrations, low buffering capacities and low total suspended solids. The removal of N-NH4 from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. This study investigates how the molecular composition of rendering condensate wastewater undergo changes in its chemistry in order to achieve suitability to be treated using hydrophobic membranes and form a suitable product. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene (PP) and polytetrafluoroethylene (PTFE) at pilot scale and carry out: (i) Process modification for NH3 molecule removal and (ii) product characterization from the process. The results demonstrate that PP membranes are not compatible with the condensate waste as it caused wetting. The PTFE membranes showed potential and had a longer lifetime than the PP membranes and removed up to 64% of NH3 molecules from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater.
Highlights
Increasing research interest has focused on the use of hydrophobic membrane contactors in recent years as a method of recovering ammonia (NH3) molecules from wastewater (WW) streams due to a number of advantages including: fast separation from WW due to the large surface area of the membranes, low energy input per mole of (NH3) removed, production of a viable fertilizer as the final product which can be sold, independent control of gas and liquid flow rates, and ease of operation [1,2]
The PTFE and PP membranes were characterized and the effect rendering facility condensate wastewater (RCWW) posed on the membranes was investigated
The results showed that the pH changes depending on the temperature of the RCWW and as the temperature increases, the pH increases which results in an decreased volume of NaOH being required to achieve the optimum pH to change the NH4 into gaseous NH3
Summary
Increasing research interest has focused on the use of hydrophobic membrane contactors in recent years as a method of recovering ammonia (NH3) molecules from wastewater (WW) streams due to a number of advantages including: fast separation from WW due to the large surface area of the membranes, low energy input per mole of (NH3) removed, production of a viable fertilizer as the final product which can be sold, independent control of gas and liquid flow rates, and ease of operation [1,2]. In order to achieve the required legislative limits, an efficient method to remove (NH3) molecules must be installed, integrated to the WW treatment facility, with low operational and capital costs and short retention time This makes the use of hydrophobic membrane contactors ideal as various studies have shown as much as 99% (NH3) removal from waste streams [11]. PA) bnefionrietiaanl dcaofstterabneainlygsiesxpoofseNdHto thmeoRleCcWulWe raetmdioffvearlenutstinmge hinytderrovpahlso.bAicn mineitmiabl rcaonset acnoanlytascistoorfsNwHit3hmporleocduulcetrioenmoovfaal musminognhiuymdrospuhlpohbiactem(e(mNbHra4)n2SeOco4)ntuancdtoerrs dwififtehrpenrotdoupcetiroantionfgamcomndonitiuomnssuislpphraetsee(n(NtedH.4)T2hSOe 4m) uanssdetradniffsfeerrenetfofipcieernactiyngacnodndwiteiottnasbilsitpyreosef nttheed. mTheme mbraasnsetsrarnesfdeerterffimciineendcy, aannddthwee(tNtaHbi4l)i2tSyOo4fptrhoedmucetmchbararancetserairsetidcsetaerremdiinsceuds,saendd. the (NH4)2SO4 product characteristics are discussed
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