Team:SCAU-China/implementation
End users
Often, bacteria colonize the endotracheal or tracheostomy tube and are embolized into the lungs with each breath. Bacteria may also be brought down into the lungs with procedures such as deep suctioning or bronchoscopy, the mucus lining the bronchial tree etc. Ciliary action of the cells lining the trachea drives the mucus superiorly, leading to a build-up of fluids around the inflated cuff where there is little to no airway clearance. The bacteria then colonize readily, reach the alveoli and fill up the sacs with liquids which causes pus and breathing issues. The late-onset VAP is caused by methicillin-resistant S. aureus (MRSA), P. aeruginosa, Acinetobacter baumannii (drug-resistant group) which causes increased morbidity and mortality.
Figure 1: Process flow of sewage treatment plant
Imagine how to use
We hope to design a pool in the sewage treatment plant to place our device. The size of the pool may be determined jointly according to the rate of flow of the sewage treatment plant, the absorption efficiency of the device and the pollution level of heavy metals. We may also need a real-time detection device for heavy metal ions in sewage to measure the concentration of heavy metal ions at the inlet and outlet of the pool, so as to ensure the good operation of our device. Use in the natural environment may be more complex. We need to prevent the destruction of our devices by organisms in the external natural environment. In the future, we hope to have electronic devices, such as Bluetooth and wireless network, to help users. Remind them when they need to recycle the device and carry out the next operation.
Other challenges
Commercialization: We believe that the current device cost is not as low as other methods. We need higher cost performance to convince potential investors in the future, such as environmental protection enterprises and sewage treatment plants. The commercialized batch operation mode may bring us new opportunities.
Large scale use: large scale use has always been our desired direction, but due to various limitations, we did not verify large-scale use in real world. This means that our large-scale fixed mode may be immature. In the future, we may continue to complete this step by human practice.
Membrane contamination: With the activity of microorganisms in the device. An increasing number of microbial metabolites can form membrane contamination. Membrane contamination is formed by the accumulation of fouling colloids, organics, extracellular polymers, as well as soluble biological products, etc. These things will attach the membrane surface to form a cake layer or by the attachment of membrane pores inside to form membrane pore blockage. A too long residence time also increases the amount of dissolved organic matter in the sewage and forms a layer of gel outside the membrane, which in turn causes the membrane's open porosity to decrease and the water flux to dramatically decrease, which will eventually affect the use effect of our device (Song Wanzhao and Yang Yunjun, 2012; Liu Yajuan and Zhao Jianguo, 2016). Currently, the commonly adopted method is the dosing of powdered activated carbon, which acts to adsorb colloidal substances and solutes in the supernatant, but excessive dosage still increases membrane contamination, as well as increasing costs. Flocculants are also a more commonly used dosing agent to reduce supernatant small particulate matter by disrupting the stability of the mixed liquid colloids, but this method can produce by-products that will elicit negative effects. The choice of control methods for membrane contamination in membrane bioreactors is more inclined to membrane alteration and membrane cleaning, such as improving the terminal hydrophilicity through surface modification, enabling better control of membrane contamination. The surface roughness was more manifested to promote the formation of membrane contamination. The more hydrophilic membrane could reduce the formation of membrane fouling (Sun Da Shi et al., 2016). In the future we may enhance the stability of the device by putting an appropriate amount of activated carbon powder in the device, or by treating the membrane.
References
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- 刘雅娟, and 赵建国. (2016).膜生物反应器中膜污染机理研究. 山西大同大学学报(自然科学版) 32, 36-39.
- 谢观体. (2021). 污水处理厂污水深度处理工艺运行比对. 广东化工 48, 137-138.
- 宋万召, and 杨云军. (2012). 膜生物反应器膜污染机理及控制措施分析. 北方环境 24, 177-179.
