The production of biofuels using wastewater as a microalgae culture medium is a little explored technology, but with potential for success. In order to contribute to the knowledge of these technologies and their technical feasibility for microalgae growth, in this work the Chlorella sp. strain was cultivated in two types of effluents generated in an experimental farm located in eastern Colombia, before and after a biological treatment process. The consumption of the main nutrients that regulate growth and lipid production was evaluated, in order to extract, quantify, characterize and convert them into biodiesel. The results showed that Chlorella sp. growth and lipid production is more favourable in R2 medium of treated water than in R1 medium of raw water, mainly due to phosphorus limitation and higher N-NO3 concentration in R2 compared to R1. In the R2 medium culture, a percentage of 42.54% of long-chain fatty acids was found, which is necessary to obtain a high quality biodiesel. Finally, the best transesterification experiment allowed reaching a fatty acid methyl esters (FAME) percentage of 90.1 ± 2.7%. In general, the results demonstrated the potential viability of using the wastewater generated in the San Pablo farm to produce biomass with lipid content to obtain biodiesel, finding that where the concentration of nutrients, mainly nitrogen, has a great influence on the microalgal metabolism for lipid accumulation.

Atrazine (ATR) is a widely used chlorinated herbicide from the s-triazine group. Due to the widespread use of ATR, it leaks into the environment and is detected in drinking water, exceeding the WHO-acceptable concentration of atrazine in drinking water, which is 2 μg/L. The aim of our study was to determine toxicity, protein degradation and genotoxicity of ATR at concentrations of 10; 1; 0.1; 0.01 mg/L on Chlorella vulgaris and with the application of E. coli bioluminescent biosensor strains. We measured the content of chlorophyll a, b, carotenoids in Chlorella vulgaris and the inhibition of this algae culture growth. E. coli RFM443 strains with gene constructs grpE:luxCDABE, lac:luxCDABE, recA:luxCDABE and E. coli strain MM294 trc:luxCDABE were used to determine toxicity, degradation of cellular proteins and genotoxicity. On the base of the obtained results, we concluded that ATR in the tested concentrations shows a toxic effect in relation to Chlorella vulgaris. ATR is toxic and genotoxic in E. coli RFM443 strains with grpE, lac, recA promoters and causes degradation of cellular proteins. Moreover, we have detected ATR toxicity toward the GFP protein in E. coli strain MM294-GFP. Taking into account the toxicity and genotoxicity of ATR documented in our research and in the experiments of other authors, we conclude that the presence of this herbicide in surface waters and drinking water is a serious threat to living organisms.

The article presents a novel solution based on dairy wastewater sorption on a biochar substrate obtained through thermal decomposition of Chlorella sp. algae biomass. The algal biomass obtained in the culture medium containing wastewater from dairy production was separated from the culture medium through sedimentation and centrifugation and then freeze-dried. After freeze-drying, the dry biomass was pyrolysed at 600 °C in a CO ₂ atmosphere.The EDS analysis showed that the oxygen-tocarbon (O/C) and nitrogen-to-carbon (N/C) ratios in the obtained material averaged 0.24 and 0.54 respectively. The arrangement and structure of the obtained biochar was evaluated using Raman spectroscopy. The observed spectra revealed the presence of D bands located at 1346–1354 cm ^-1 and corresponding to disordered carbon structures, as well as G bands located at 1585–1594 cm ^-1 and corresponding to tensile vibrations. The D/G intensity ratio was determined at 0.28. The next phase of the research involved sorption of dairy wastewater from cleaning processes containing 1 g of the obtained biochar using solid phase extraction. The study results confirmed high sorption efficiency of the obtained algal biochar. Turbidity was reduced by 93%, suspension by 88%, sulphates by 61%, chlorides by 80%, and organic carbon by 17%. The research confirmed the possibility of using wastewater from dairy production as a natural culture medium for Chlorella sp. algae cultivation to manufacture valuable biochar, which could be used as a sorption bed in the treatment of dairy wastewater from cleaning processes.

There are approximately 15 million users of system heat in Poland, but unfortunately nearly 70% of the fuel used in heat production is fossil fuel. Therefore, the CO2 emission reduction in the heat production industry is becoming one of the key challenges. City Heat Distribution Enterprise Ltd. in Nowy Sącz (Miejskie Przedsiębiorstwo Energetyki Cieplnej sp. z o.o.) has been conducting a self-financed research and development project entitled The use of algae as carbon dioxide absorbers at MPEC Nowy Sącz. The project deals with postcombustion CO2 capture using Chlorella vulgaris algae. As a result of tests conducted in a 1000 l hermetic container under optimal temperature and light conditions, the recovery of biomass can be performed in weekly cycles, yielding approximately 25 kilograms of biomass per year. Assuming that half of the dry mass of the algae is carbon, it can be said that 240 grams of carbon is bound in one cycle, which, converted to CO2, gives 880 grams of this gas. Our results showed that around 45.8 kilograms of CO2 per year was absorbed. Additionally, it is possible to use waste materials and by-products of technological processes as a nutrient medium for algae

The aim of this study was to examine the possibility of use of synchronous culture of Chlorella vulgaris algae as a biotest in water quality control. In the experiment the samples of water collected from seven sampling points in Goczałkowice Reservoir were used. The criterion of changes was the concentration of photosynthetic pigments, from 24'" hour of the cell life cycle, separated by HPLC technique. On the basis of changes taking place in the cells of the algae cultures it was possible to establish the timing of the flood period and autumnal changes in a water quality. It was also proved that the water quality in the main water current that fall into the western part of reservoir carried by the Wisła River after the flood period significantly differed from the water quality in the other parts of the reservoir, particularly in its eastern section.