Performance Assessment of a Laboratory Scale Prototype Biofiltration System in Tropical Region

Abstract

Biofiltration systems, as one of the best management practices, have good potentials to improve stormwater quality and hydrology of urban catchments. While biofiltration systems are well-studied in developed countries, the majority of those studies are conducted for temperate climate and there is a lack of lab-scale and field-scale studies on such systems under tropical conditions. This paper focuses on the performance of a lab-scale prototype biofiltration systems in stormwater retention efficiency as well as pollutants removal (including heavy metals and nutrients) from synthetic stormwater reproducing tropical rainfall events. A three-layer sand-based filter media with two different native plants including Pedilanthus tithymaloides and Cyperus alternifolius was selected for this study. Results showed that the system with Cyperus has a better stormwater retention capacity compared to the one with Pedilanthus. In addition, the observed infiltration rate in Cyperus and Pedilanthus were 338 mm/h and 267 mm/h, respectively. The better hydraulic performance in the system with Cyperus was attributed to the deeper and more extensive root penetration of this plant (as deep as 800 mm) compared to Pedilanthus (as deep as 250 mm). While both systems failed to perform well in removing total nitrogen, they performed significantly better in removing total phosphorus (Cyperus and Pedilanthus removed 67.3% and 62.5% of total phosphorus, respectively). The statistical analysis of results showed that the top 100 mm layer of filter media is the main contributor to total phosphorus removal. However, no major differences were observed between the two systems in phosphorus removal. Moreover, both systems were also capable of removing the available heavy metals (i.e., Fe, Cu, Mn, Ni, Pb, and Zn) as the removal efficiencies exceeded 90%, except for Fe (76%). Similar to phosphorus, it was concluded that the top layer is the major contributor to the heavy metals removal. Overall, the biofiltration system using Cyperus was found to be a successful system for operating under tropical conditions.

Pilot and Field Studies of Modular Bioretention Tree System with Talipariti tiliaceum and Engineered Soil Filter Media in the Tropics

“…TSS and TP removals were consistent over time for Phase 1 and Phase 2. It was reported that TSS and TP removals were independent of the tree species used and were more influenced by the media used [36,71]. Likewise, heavy metal removals were more dependent on the media used and were less contributed to by different plant species.…”

“…The unique design of the MBT system's unique design aims to increase the storage capacity of the BRS per surface area by having a deeper filter media layer compared to conventional systems, allowing it to treat more water in the system. Generally, the media layer was reported to be around 0.4 m [9,36]. A deeper filter media layer of 1.0 m also allows sufficient space and soil depth for the root growth of the tree species planted in the MBT system.…”

“…A higher dissolved fraction of influent phosphorus resulted in the lower phosphorus removal performance of the MBT. As adsorption is the major removal mechanism for phosphorus in BRS [10,36,98], the phosphorus adsorption capacity of the filter media is an important parameter in managing and removing dissolved phosphorus.…”

Exploring the Potential in LID Technologies for Remediating Heavy Metals in Carwash Wastewater

“…Some plants showed a better performance in nutrient and heavy metal removal, such as bamboo (Bambusoideae), rosea variegata (Graptophyllum pictum), the ti plant (Cordyline fruticosa), and the umbrella palm plant (Cyperus alternifolius) [64]. Furthermore, some studies have shown that using two different plant species will increase the performance of a system's nutrient removal and increase the plants' resistance to adverse environmental conditions [73].…”

Urban stormwater characterization, control, and treatment

“…High pollutant loadings did not impact photosynthesis rates or chlorophyll content for most plants, though the height of shrubs was significantly affected. A laboratory‐scale biofiltration unit was built and operated in Malaysia to examine the performance under tropical rainfall conditions (Hermawan et al, 2019). The system was split into two hydraulically isolated sections, each section planted with a native plant species— Cyperus alternifolius or Pedilanthus tithymaloides .…”