Bioremediation efficacy—comparison of nutrient removal from an anaerobic digest waste-based medium by an algal consortium before and after cryopreservation

Abstract

An algal consortium was isolated from an integrated steelmaking site at TATA Steel Strip Products Ltd. in Port Talbot, UK, and its bioremediation capacity tested. Excellent “bioremediation” was observed when the mixed culture was “applied” to diluted effluent from an enhanced anaerobic digestion plant at Dŵr Cymru Welsh Water at Port Talbot, UK. After 5 days of cultivation in a 600-L photobioreactor, 99% of the total nitrogen (initial level, 4500 μmol L−1) and total phosphorus (initial level, 690.4 μmol L−1) were removed from the waste stream. The consortium was deposited in the Culture Collection of Algae and Protozoa (CCAP), an international depository authority for microalgal patents, as CCAP 293/1. This material has been successfully cryopreserved using a two-step cryopreservation protocol with dimethyl sulphoxide (5% v/v) used as a cryoprotectant. On recovery of samples after 3 months storage at −196 °C, the specific bioremediation activity of the revived consortium was tested. The capacity of the revived culture to bioremediate effluent was not significantly different (p < 0.05) from a non-cryopreserved control, with 99% of total nitrogen and phosphorus remediated by day 4. Although non-axenic algal cultures have previously been cryopreserved, this is the first report of the successful cryopreservation of mixed algal consortium, with validation of its ability to bioremediate after thawing comparing non-cryopreserved cultures with a revived post-thaw algal consortium. The study also highlights the need to ensure the long-term security and the requirement to validate the functionality of conserved inocula with biotechnological/bioremediation potential.

Formulation and utilisation of spent anaerobic digestate fluids for the growth and product formation of single cell algal cultures in heterotrophic and autotrophic conditions

“…Several applications of this technology, namely the use of anaerobically digested effluents in aquaculture, regarding growth of microalgae within the scope of phycoremediation and commodities generation, have been effective in South East Asia and Mediterranean countries including Israel, Spain and Portugal (Rawat et al, 2011;Pereira et al, 2012;Silkina et al, 2017). Microalgae are highly adaptable organisms, resistant to the heavy metals and other toxins, able to use macro (nitrogen, phosphorus) and micro (vitamins, minerals) nutrients for successful growth.…”

Short-term deleterious effects of standard isolation and cultivation methods on new tropical freshwater microalgae strains

“…An additional advantage of algal biomass production is the potential use of wastewater as culture media for the production of middle and high-value by-products. The use of wastewater is beneficial as it reduces the use of freshwater, decrease the cost of nutrient addition, and helps in the removal of nitrogen and phosphorus which otherwise would end in the environment (Chiu et al, 2015), and have been show that several microalgae have high bioremediation potential as Chlorella and Scenedesmus (Silkina et al, 2017). However, wastewater has an elevated amounts of nitrogen, phosphorus and microbes, which could affect algal productivity (Mara, 2004;Mahapatra & Ramachandra, 2013) Therefore, an efficient strategy to mitigate potential negative effects of the use of wastewater as culture media is the isolation of wild algal strains that proliferate in it (Mahapatra & Ramachandra, 2013).…”

Short-term deleterious effects of standard isolation and cultivation methods on new tropical freshwater microalgae strains

“…1). Consensus sequence percentage 6 showed a 90% of similarity between M2 and M6 in nucleotide alignment. Sequences from M2 Scenedesmus and Desmodesmus (Fig.…”

“…However, high temperatures can severely affect the 14 productivity of said systems (Béchet et al, 2013). For this reason, it has become important the 15 isolation and characterization of high temperature-tolerant microalgal species in order to Chlorella and Scenedesmus (Silkina et al, 2017). However, wastewater has an elevated amounts 1 of nitrogen, phosphorus and microbes, which could affect algal productivity (Mara, 2004; 2 Mahapatra & Ramachandra, 2013) Therefore, an efficient strategy to mitigate potential negative 3 effects of the use of wastewater as culture media is the isolation of wild algal strains that 4 proliferate in it (Mahapatra & Ramachandra, 2013).…”