Graphical abstract

In the last 10 years, the microbial fuel cell (MFC) has been extensively studied worldwide to extract energy from wastewater via electricity generation. More recently, a merged technique of embedding MFC into a constructed wetland (CW) has been developed and appears to be increasingly investigated. The driving force to integrate these two technologies lies in the fact that CWs naturally possess a redox gradient (depending on flow direction and wetland depth), which is required by MFCs as anaerobic anode and aerobic cathode chambers. No doubt, the integration of MFC with a CW will upgrade the CW to allow it to be used for wastewater treatment and, simultaneously, electricity generation, making CWs more sustainable and environmentally friendly. Currently, published work shows that India, China, Ireland, Spain, Germany and Malaysia are involved in the development of this technology although it is in its infant stage and many technical issues are faced on system configuration, operation and maximisation of electricity production. This paper aims to provide an updated review and analysis of the CW-MFC development. Focuses are placed on the experience gained so far from different researchers in the literature and further research directions and proposals are discussed in great detail.

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This study compares and contrasts the glyphosate removal efficiency of alum sludge (waterworks residue) and Irish peat in aqueous solution. Organic phosphonate of glyphosate aqueous solution was removed in pot tests separately filled with peat and alum sludge, while effluent samples were taken from each pot to analyse the concentration of phosphorus (P) and COD (chemical oxygen demand); physical and chemical analysis for both media before and after use was carried out subsequently. The results show that the P removal capacity of alum sludge was significant (>99%), while the removal capacity of peat was considerably less than 10% after 10 weeks. Both materials significantly reduced the levels of COD, but it was noted that peat had a marginally greater initial P removal capacity (68 ± 22%) and did perform better than alum sludge (57 ± 12%). Moreover, pre-treatment is a crucial step to harness the full potential of peat. Overall, this study provides a scientific clue for sorbents selection when considering alum sludge and peat to maximize their value in practice.

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