Lemnaceae clones collected from a small geographic region display diverse traits relevant for the remediation of wastewater

Abstract

The Lemnaceae (duckweed) are a family of aquatic plants which can be used as part of a circular economy approach to remediate and valorise wastewater. The suitability of duckweeds relates to their tolerance of wastewater conditions, fast growth rates and valuable biomass. Duckweed species and clones display a wide range of remediation abilities and nutritional composition. In order to find duckweed species and clones best suited for remediation and valorisation of dairy processing wastewater, plant samples were collected from a number of locations around southern Ireland. These species and clones were cultured on a synthetic dairy processing wastewater while growth, TN/TP removal and protein content were assessed. Synthetic dairy wastewater was found to be suitable for remediation by different species and clones. However, significant differences were found in relative growth rate (RGR), TN removal rate and protein content. As per PCA, it was found that species and clones with higher RGR tended to have a lower protein content. Furthermore, nutrient removal rate was not strongly associated with growth and protein content. The results demonstrate that remediation is not positively correlated with valorisation across duckweed species and clones. Thus, clonal selection for duckweed reactors will need to consider the prime objective of remediation i.e. biomass production or wastewater remediation. • Synthetic dairy processing wastewater is suitable medium for duckweed growth. • Significant diversity in remediation relevant traits between Lemnaceae clones. • Nitrogen uptake is only loosely associated with biomass yield. • High protein content is associated with lower growth. • No single duckweed clone is optimal for both remediation and valorisation.