Pilot Scale Study: First Demonstration of Hydrophobic Membranes for the Removal of Ammonia Molecules from Rendering Condensate Wastewater

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.

Potential Viable Products Identified from Characterisation of Agricultural Slaughterhouse Rendering Wastewater

“…However, this method is only capable of producing a NH 3 fertiliser, whereas the use of membrane distillation allows for the production of (NH 4 ) 2 SO 4 . Hydrophobic membranes have become increasingly popular for extracting NH 3 from WW streams [23,43]. One of the major benefits of using membranes to treat NH 3 in WW is the production of an NH 4 salt (most commonly (NH 4 ) 2 SO 4 ) as a by-product [44].…”

“…The high levels of NH 3 present in RCWW makes it an ideal matrix to produce (NH 4 ) 2 SO 4 fertilizer. A study by Brennan et al [23] stated that the operation costs to produce 1 kg of (NH 4 ) 2 SO 4 was €2.48 and could be sold for €1.54. It was calculated that the present RCWW produces an average of 4.7 million kg of NH 3 a year, which would allow for the production of up to 711,866 kg of 30% (NH 4 ) 2 SO 4 , equating to 1.1 million euro in revenue.…”

“…NH 3 discharge has a strong correlation with the amount of protein that has been degraded. NH 3 present in the WW can be removed by using the denitrification process or it could be recovered by using hydrophobic membranes, and when reacted with sulphuric acid (H 2 SO 4 ), it produces ammonium sulphate ((NH 4 ) 2 SO 4 ), which can be used as a nitrogen and sulphur-rich fertiliser [22,23]. Cattle bones are mostly composed of hydroxyproline, N and calcium hydroxyapatite (CaHA) at 3.7, 5.8 and 57.8%, respectively [24].…”

Ion and Molecule Transport in Membrane Systems 2.0

“…There are publications aimed at the preparation and study of novel artificial membranes [ 5 , 6 , 7 , 8 , 9 , 10 ]. M. Mofasserul Alam et al [ 5 ] prepared and studied a novel anion-exchange membrane designed to separate bisulfite anion from mixt solutions.…”

“…It was found that the main cause of improving membrane behavior after the surface modification is electroconvection. The effect of the nature of hydrophobic material on the operation parameters of membrane contactors used to remove ammoniacal nitrogen (N-NH 4 ) molecules from wastewater was studied by B. Brennan et al [ 9 ]. It was found that polypropylene membranes are incompatible with the condensate waste, while the polytetrafluoroethylene membranes showed high performance in removing up to 64% of NH 3 molecules from the condensate waste.…”