- Alette A.M. Langenhoff (1)
- Leire Caizán-Juanarena (1)
- Xuan Chen (1)
- Ekkehard Christoffels (1)
- Andrea F. Brunsch (1)
- Huub H.M. Rijnaarts (1)
- Annemiek Heijne ter (1)
- Cees J.N. Buisman (1)
- Thomas L. Laak ter (1)
- Ivonne Servin-Balderas (1)
Electrochemical and microbiological characterization of single carbon granules in a multi-anode microbial fuel cell
Caizán-Juanarena, Leire ; Servin-Balderas, Ivonne ; Chen, Xuan ; Buisman, Cees J.N. ; Heijne, Annemiek ter - \ 2019
Journal of Power Sources 435 (2019). - ISSN 0378-7753
Capacitive bioanode - Charge storage - Charge/discharge cycles - Granular activated carbon - Microbial community - Total nitrogen
Capacitive microbial fuel cells (MFCs) use bacteria on a capacitive anode to oxidize organics in wastewater and simultaneously charge the electrode. This study aims to gain knowledge on the performance of single activated carbon (AC) granules, which are used as capacitive bioanodes. To this end, a multi-anode MFC that allows the testing of up to 29 granules under the same experimental conditions is used. 2 types of AC granules (PK and GAC) and 3 different size-ranges (n = 8 each) are studied in terms of current production, biomass quantification, microbial community and charge storage. Additionally, charge storage of PK granules (n = 24) is determined for different charging/discharging times. Results show that total produced charge directly relates to biomass amount, which has a linear relation towards granule outer surface area. Small AC granules have higher volumetric current densities, which could be of interest for their application in up-scaled reactors. PK granules show slightly higher biomass and current production than GAC granules, while these latter ones show larger volumetric charge storage capacity. Similarly, it is shown that short charging/discharging times are needed to obtain maximum charge storage and current output. These findings are of importance to design and operate MFCs with capacitive properties.
Retention soil filter as post-treatment step to remove micropollutants from sewage treatment plant effluent
Brunsch, Andrea F. ; Laak, Thomas L. ter; Christoffels, Ekkehard ; Rijnaarts, Huub H.M. ; Langenhoff, Alette A.M. - \ 2018
Science of the Total Environment 637-638 (2018). - ISSN 0048-9697 - p. 1098 - 1107.
Constructed wetlands - Granular activated carbon - Micropollutants - Post-treatment step - Retention soil filter - Wastewater treatment
Retention soil filters (RSFs) are a specific form of vertical flow constructed wetlands for the treatment of rain water and/or wastewater. We have tested 3 pilot RSFs to investigate removal of dissolved organic carbon (DOC) and 14 different organic micropollutants (OMPs) from the effluent of a large scale sewage treatment plant (STP). Two of them were operated as conventional RSF with material (sand with CaCO3 and organic matter) from two different full-scale RSFs. The third pilot RSF contained filter material (sand with CaCO3) with additional biochar in the upper layer (0–10 cm) and granulated activated carbon (GAC) in the lower layer (60–90 cm). The filters were planted with Phragmites australis. The RSFs were operated and monitored for 3 years, and water samples were taken regularly at inflow, outflows and in 3 depths within the filters. In total 523 samples were taken. In the conventional RSF, best median removal was detected for galaxolide, diclofenac 4-hydroxy, metoprolol and clarithromycin (75–79%). No removal was seen for sulfamethoxazole and carbamazepine. The DOC and OMP removal in the conventional RSFs was best in the upper layer with highest organic matter content, increased in time over the three years of operation and also with extended contact time. In the effluent of the RSF with GAC, 10 out of the 14 OMPs could not be detected; 4 OMPs were detected, but only metformin with removal < 80%, thus showing a more efficient removal than the conventional RSF. A decrease in DOC removal was detected in the GAC layer (>88% to 60%) over the 2.5 years of operation. Biochar was most effective in OMP removal in the first operational year. It can be concluded that the increasing removal efficiency of the conventional RSF material – also present in the RSF with biochar and GAC – might mitigate the reduced efficiency of the sorbent additives biochar and GAC. This enables to extend the operational lifetime of the filters with acceptable removal rates. Finally, our study demonstrates that an RSF with GAC shows an enhanced removal of OMPs, which is a suitable post-treatment step for STPs.