Parameter-efficient bioclogging model: calibration and comparison with laboratory data

Mechanisms and mitigation control of clogging in constructed wetlands: Insight into the enhancement of the bioelectrochemical systems

Constructed wetlands (CWs), a cost-effective and eco-friendly wastewater treatment technology, are extensively applied in various types of wastewater treatment. There is a series of strong impacts on CWs performance by the accumulation of clogging matters which attribute to physical, chemical, and biological processes after the long-term operation. This paper summarizes the mechanism of clogging formation, which can be classified into physical, chemical, and biological clogging. Moreover, it analyzes the typical measures for preventing and controlling clogging in CWs. The integration of bioelectrochemical systems (BES), including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) into CWs is proposed as a safe and efficient way to alleviate substrate clogging on-site, owing to the fact that BES can easily automate the control or adjustment of its internal electric field form. The mechanism of clogging control by CW-BES is comprehensively described and analyzed. With the help of BES, the clogging substances obtained optimized occurrence form, reduced hydrophobicity and advantageous spatial distribution. Besides, the microbial community achieved promoted structure, accelerated rates of electron transfer and more diverse metabolic pathway. Compared to traditional methods for evaluating the clogging of CWs, the MFC sensor offers the advantages of being fast, enabling in-site detection, and being non-destructive. Future research should be focused on the theoretical underpinnings for putting CW-BES into practical use. Additional, efforts should be made to ensure the stable, long-term operation of CWs.

The State of the Art of Clogging in Vertical Flow Wetlands

Clogging in vertical flow (VF) wetlands is an important process influencing water purification processes. The main contributing factors are the growth of microorganisms within the filter media, the accumulation of suspended solids on top of the wetland, as well as within the filter media. Both processes lead to a decrease of the available pore space, hence changing the soil’s hydraulic properties. This will alter the water flow and cause malfunctioning of the system. This paper summarizes the state of the art of the prevailing physical, biological and chemical processes influencing clogging in VF wetlands. Different design and operational parameters are discussed to give a better understanding on their influence to prevent malfunctioning. Based on a literature review, a detailed overview on experimental as well as modelling studies carried out is presented. The main conclusions are that on the one hand, important insights on clogging processes in VF wetlands have been gained but, on the other hand, design parameters such as intermittent loading operation and the grain size of the filter media are not well represented in those studies. Clogging models use different conceptual approaches ranging from black box models to process based models.