Pilot-scale, on-site investigation of crushed recycled glass as tertiary filter media for municipal lagoon wastewater treatment

ABSTRACTGlass recycling is a process that faces many obstacles, especially in the closed-loop context. Waste glass separation and transportation can become quite expensive, turning glass collection for remanufacture unfeasible. For this reason, it is important that alternative markets for waste glass are sought. This study evaluated crushed recycled glass as tertiary media in subsurface pilot-scale filters for on-site municipal wastewater treatment, using control sand media filters. Filters were operated over 128 days at a 24-h hydraulic retention time, treating secondary lagoon effluent from the rural municipality of Dunnottar, Manitoba, Canada. Crushed recycled glass filters removed 92%, 90% and 45% of the total suspended solids (TSS), ammonium nitrogen (NH₄⁺-N) and chemical oxygen demand (COD), respectively. Total suspended solids were removed equally well in sand and crushed recycled glass filters (α = 0.05), whereas NH₄⁺-N and COD reductions were 10% and 21% greater in sand media, respectively. Both sand and crushed recycled glass filters failed to achieve phosphorus (P) discharge guidelines. This study shows that there is potential for crushed recycled glass in wastewater filtration, especially to achieve TSS, COD and NH₄⁺-N removal. Small communities served by waste stabilization ponds could benefit from glass media filters, as waste glass could be diverted from curbside collection and utilized locally to polish municipal lagoon effluent.

The potential for bioaugmentation of sand filter materials from waterworks using bacterial cultures degrading 4-chloro-2-methylphenoxyacetic acid

BACKGROUND

The herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) is found frequently in Danish groundwater in concentrations exceeding the EU threshold limit of 0.1 µg L(-1) . Groundwater is used for drinking water, and one potential remediation strategy is bioaugmentation using inoculation of sand filters at affected waterworks with degrader bacteria. Numerous bacteria degrading phenoxyacetic acid herbicide have previously been isolated, and they may be candidates for bioaugmentation processes. Designing the optimum inoculum, however, requires knowledge of the capacity for degrading realistically low herbicide concentrations and the robustness of the bacteria when inoculated into sand filter materials.

RESULTS

Testing a range of different MCPA-mineralising bacterial combinations, using a high-throughput microplate radiorespirometric mineralisation assay, highlighted three efficient cocultures for mineralising low MCPA concentrations. Cocultures demonstrating a shorter time delay before initiation of (14) C-ring-labelled MCPA mineralisation to (14) CO2 , and a more extensive mineralisation of MCPA, compared with those of single strains, were found. When inoculated into different sand filter materials, the coculture effect was diminished, but several single strains enhanced MCPA mineralisation significantly at low MCPA concentrations.

CONCLUSION

This study shows that an increase in the potential for mineralisation of low herbicide concentrations in sand filter materials can be achieved by inoculating with bacterial degrader cultures. © 2014 Society of Chemical Industry.

Urban runoff treatment using nano-sized iron oxide coated sand with and without magnetic field applying

Increase of impervious surfaces in urban area followed with increases in runoff volume and peak flow, leads to increase in urban storm water pollution. The polluted runoff has many adverse impacts on human life and environment. For that reason, the aim of this study was to investigate the efficiency of nano iron oxide coated sand with and without magnetic field in treatment of urban runoff. In present work, synthetic urban runoff was treated in continuous separate columns system which was filled with nano iron oxide coated sand with and without magnetic field. Several experimental parameters such as heavy metals, turbidity, pH, nitrate and phosphate were controlled for investigate of system efficiency. The prepared column materials were characterized with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDXA) instruments. SEM and EDXA analyses proved that the sand has been coated with nano iron oxide (Fe3O4) successfully. The results of SEM and EDXA instruments well demonstrate the formation of nano iron oxide (Fe3O4) on sand particle. Removal efficiency without magnetic field for turbidity; Pb, Zn, Cd and PO4 were observed to be 90.8%, 73.3%, 75.8%, 85.6% and 67.5%, respectively. When magnetic field was applied, the removal efficiency for turbidity, Pb, Zn, Cd and PO4 was increased to 95.7%, 89.5%, 79.9%, 91.5% and 75.6% respectively. In addition, it was observed that coated sand and magnetic field was not able to remove NO3 ions. Statistical analyses of data indicated that there was a significant difference between removals of pollutants in two tested columns. Results of this study well demonstrate the efficiency of nanosized iron oxide-coated sand in treatment of urban runoff quality; upon 75% of pollutants could be removed. In addition, in the case of magnetic field system efficiency can be improved significantly.