The Effect of Mixed Wastewaters on the Biomass Production and Biochemical Content of Microalgae

The effect of ammonia and iron concentration in Bold Basal Medium and mixed wastewater (including pretreated piggery wastewater and acid mine drainage) on biomass production and biochemical content (lipid and ß-carotene) of microalgae (Uronema sp. KGE 3) was investigated. Addition of iron to the Bold Basal Medium enhanced the growth, lipid, and ß-carotene of Uronema sp. KGE 3. The highest dry cell weight, lipid content, and lipid productivity of KGE 3 were 0.551 g L-1, 46% and 0.249 g L-1 d-1, respectively, at 15 mg L-1 of Fe. The highest ß-carotene was obtained at 30 mg L-1 of Fe. The biomass production of KGE 3 was ranged between 0.18 to 0.37 g L-1. The microalgal growth was significantly improved by addition of acid mine drainage to pretreated piggery wastewater by membrane. The highest dry cell weight of 0.51 g L-1 was obtained at 1:9 of pretreated piggery wastewater by membrane and acid mine drainage for KGE 3. The removal efficiencies of total nitrogen and total phosphate was ranged from 20 to 100%. The highest lipid and ß-carotene content was found to be 1:9. Application of this system to wastewater treatment plant could provide cost effective technology for the microalgae-based industries and biofuel production field, and also provide the recycling way for pretreated piggery wastewater and acid mine drainage.

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Bacterial Oxidation of Ferrous Iron and RISCs at Low Temperatures: Their Effect on Acid Mine Drainage and Bioleaching of Sulphide Minerals

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.71-73.433 ◽

2009 ◽

Vol 71-73 ◽

pp. 433-436 ◽

Cited By ~ 1

Author(s):

B. Escobar ◽

S. Buccicardi ◽

G. Morales ◽

J.V. Wiertz

Keyword(s):

Acid Mine Drainage ◽

Low Temperatures ◽

Mine Drainage ◽

Basal Medium ◽

Copper Production ◽

High Price ◽

Low Grade ◽

Isolated Cells ◽

Sulphide Minerals ◽

Acid Mine

Chilean copper production has been growing in the last 20 years reaching an annual production of 5,557,000 tons of Cu in 2007. For each ton of copper produced, about 200 tons of sterile and low grade ore and 100 tons of tailings are discharged in the environment. Most of these wastes contain significant amounts of sulphide minerals, mainly pyrite, and once submitted to weathering, may produce acid mine drainage. On the other hand, the high price of copper raised the interest for processing by leaching the low grade ore deposited in large dumps. An important part of these mining wastes and low grade ores is located in the Andes, where the mean temperature is usually ~5°C or less. The rate at which bioleaching reactions occur is directly related to the temperature at which the microorganisms (bacteria and archaea) develop. A temperature decrease causes both a decrease of the rate of the involved chemical reactions and a decrease or inhibition of microbial growth. In this work we present the results of the isolation of microorganisms from an old tailing deposit, exposed at low temperatures (5oC) during most of the winter. The isolated microorganisms initially showed a low capacity to oxidize 3g/L Fe(II) sulfate at pH 1.6, and tetrathionate 0.01 M, with an initial pH 4 both at 5oC. However, after successive cultures, microorganisms showed a slow capacity to oxidize both substrates, as well as the sulphide contained in the tailings samples. The terminal Restriction Fragment Length Polymorphism (tRFLP) of the isolated cells grown in basal medium containing Fe(II) showed a nearly pure culture of Acidithiobacillus ferrooxidans. The present study indicates that, even at very low temperatures, microorganisms play an important role in the generation of acid mine drainage and in the oxidation and leaching of sulphide ores.

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