Influence of zinc and manganese enrichments on growth, biosorption and photosynthetic efficiency of Chlorella sp

• Published in: Environmental science and pollution research international Vol. 28; no. 7; pp. 8539 - 8555
• Main Authors: Ciurli, Adriana, Di Baccio, Daniela, Scartazza, Andrea, Grifoni, Martina, Pezzarossa, Beatrice, Chiellini, Carolina, Mariotti, Lorenzo, Pardossi, Alberto
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2021; Springer Nature B.V
• Subjects: Algae; Aquatic environment; Aquatic microorganisms; Aquatic plants; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioaccumulation; Biomass; Biosolids; Biosorption; Chlorella; Copper; Earth and Environmental Science; Ecotoxicology; Efficiency; Enrichment; Environment; Environmental Chemistry; Environmental Health; Environmental science; Growth rate; Heavy metals; Industrial plants; Manganese; Metals, Heavy; Nutrient content; Nutrient solutions; Photochemicals; Photosynthesis; Photosynthetic pigments; Pigments; Pollutants; Research Article; Solid wastes; Trace elements; Urban agriculture; Waste Water Technology; Water Management; Water pollution; Water Pollution Control; Zinc; Chlorophyll fluorescence; Biofertilisation; Zn and Mn balance; Trace elements; Photosynthetic pigments; Bioaccumulation
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-11033-2

Treating biosolids from industrial, urban, and agricultural plants produces high amounts of water. After organic pollutants and non-essential heavy metals have been removed, these wastewaters are still rich in trace elements such as zinc (Zn), copper, or manganese (Mn) and have high conductivity and extremely variable pH. In this study, an isolated Chlorella sp. strain was grown for 21 days in nutrient solutions enriched with known amounts of Zn or Mn to obtain concentrations three (4.0 mg L −1 )- and six (1.0 mg L −1 )-fold higher than the basal medium levels, respectively, and over the limits permitted in aquatic environments. The green alga exhibited high tolerance to Zn and Mn, with the maximum abatement of Zn (28–30%) and Mn (60–63.5%) after 14 and 7 days of culture, respectively. Mn stimulated the growth rate and biomass production of Chlorella , which showed the highest carbon levels just in the first week. In both treatments, the nitrogen and protein contents remarkably increased. The photosynthetic pigments increased until the 14th day, with a higher extent in the Zn-enriched solution. An increasing photochemical efficiency was observed after 7 days of treatment, when the microalgae grown in Zn- and Mn-enriched solutions showed a slightly higher maximum photochemical efficiency than control. The autotrophic and controlled growth system adopted was designed to monitor the dynamic balance of Zn and Mn contents in the solutions and in the algal biomass. This system has proved to be useful in identifying the optimal nutritional conditions of the microalgae, along with the optimal temporal patterns of both metal biosorption capacity for water remediation and element bioaccumulation in the algal biomass.