Application of Cellular Microencapsulation to Wastewater Nitrogen Removal

Abstract

Microencapsulation of cells is a technique in which cells are enclosed in microscopic spheroids of a desired substance, with applications in many fields, such as biomedical engineering. In this study, a microfluidic approach to encapsulate bacteria (nontoxic to humans) in polyethylene glycol-diacrylate (PEG-DA) spheroids is investigated, particularly its potential application in a multistage bacterial process to remove Nitrogen from wastewater. A mixture of the bacteria and PEG-DA solution is pumped through channels in a microfluidic device. Mineral oil is also pumped simultaneously into microfluidic channels. PEG-DA microdroplets will be generated due to the shear focusing effect of the mineral oil on the PEG-DA mixture at the cross junction in a microfluidic device, and cross-linked immediately in a straight channel by a time of UV exposure around 0.1 milliseconds. The cross-linked PEG-DA spheroids will be extracted from the mineral oil phase by centrifugation. This approach is expected to produce PEG-DA spheroids with diameter of 50 μm to 300 μm. In the case of the multi-step bacterial process, a procedure for multiple-encapsulation (yet another encapsulation of already cross-linked PEG-DA microspheres) will also be examined. The number and viability of cells in the PEG-DA spheroids is subsequently investigated.