Integrating natural and engineered remediation strategies for water quality management within a low-impact development (LID) approach

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

Carwash wastewater (CWW) can be a significant source of environmental pollution due to the diversity and high concentrations of contaminants it contains. This toxic wastewater can contain several different heavy metals that if left untreated, can enter surface and sub-surface waters. Innovative, nature-based solutions such as low-impact development (LID) technologies may provide an eco-friendly CWW treatment process that is both effective and affordable. This research reviews the available literature to provide definitive values of flowrate and contaminant concentrations found in CWW around the globe. Dividing LID technologies into two groups, vegetated and unvegetated systems, the authors explored the literature for the general performance of these technologies to sustainably treat heavy metals in CWW. Depending on the car wash’s size and intended purpose, whether cleaning vehicles in agriculture-based rural communities, mining, or in high-density urban environments, volumetric flowrates requiring treatment found in six different countries ranged from 35–400 L/car. CWW also contains a wide range of contaminants at various levels, including COD, turbidity, TDS and TSS, surfactants, oils and greases, and heavy metals such as lead, cadmium, zinc, copper, chromium, and iron. Heavy metal removal by both vegetated and unvegetated LIDs shows mixed results in the literature, but given the different processes involved in both types, the authors propose a system that combines these types in order to provide all the necessary removal processes, including mechanical filtration, adsorption, sedimentation, chemical and biological treatment processes.

Novel Integration of Geopolymer Pavers, Silva Cells and Poplar Trees for In-Situ Treatment of Car-Wash Wastewater

This paper presents an eco-friendly, low-impact development (LID) approach, developed and implemented at a car wash site for a cleaner and greener environment. In this approach, the contaminated water discharged after car washing is treated as it is directed through an engineered, ecology-based water-management design. The design involves poplar (Populus deltoides) trees, Silva Cells®, and Fly-ash based Geopolymer concrete pavers working collectively to minimize the percolation of contaminants into the soil. In this novel system, each component has a vital role. For instance, the extensive roots of the poplar trees enable water filtration owing to phytoremediation effect; while the Silva Cells® promote stormwater management, planting of poplar trees and serve as a foundation for paver blocks. Lastly, the paver blocks made from industrial waste allow it to withstand urban load and infiltrate water runoff, thereby reducing runoff quantities. To evaluate the efficacy of contaminant uptake by this system, pH, electrical conductivity and turbidity, which are indicators of water quality levels, were monitored pre- and post-treatment. The percentage change in total dissolved solids indicates the potential of this treatment system for effective treatment of the contaminated car wash water.

Nonpoint source pollution

A comprehensive review of the research papers published in 2018 focusing on nonpoint source (NPS) pollution is presented in this review article. The identification of pollution from different sources and estimation of NPS pollution using various models are summarized in this review paper. Various innovative techniques are also examined to abate NPS pollution. PRACTITIONER POINTS: The non-point source pollution in 2018 is systematically reviewed and documented. This review evaluates and summarizes the identification, quantification, reduction, and management of NPS pollution. Future perspectives of NPS pollution research are discussed.