Experimental Treatment of Hazardous Ash Waste by Microbial Consortium Aspergillus niger and Chlorella sp.: Decrease of the Ni Content and Identification of Adsorption Sites by Fourier-Transform Infrared Spectroscopy

Abstract

Despite the negative impact on the environment, incineration is one of the most commonly used methods for dealing with waste. Besides emissions, the production of ash, which usually shows several negative properties, such as a higher content of hazardous elements or strongly alkaline pH, is problematic from an environmental viewpoint as well. The subject of our paper was the assessment of biosorption of Ni from ash material by a microbial consortium of Chlorella sp. and Aspergillus niger. The solid substrate represented a fraction of particles of size <0.63 mm with a Ni content of 417 mg kg–1. We used a biomass consisting of two different organisms as the sorbent: a non-living algae culture of Chlorella sp. (an autotrophic organism) and the microscopic filamentous fungus A. niger (a heterotrophic organism) in the form of pellets. The experiments were conducted under static conditions as well as with the use of shaker (170 rpm) with different modifications: solid substrate, Chlorella sp. and pellets of A. niger; solid substrate and pellets of A. niger. The humidity-temperature conditions were also changed. Sorption took place under dry and also wet conditions (with distilled water in a volume of 30–50 ml), partially under laboratory conditions at a temperature of 25°C as well as in the exterior. The determination of the Ni content was done using inductively coupled plasma optical emission spectrometry (ICP-OES). The removal of Ni ranged from 13.61% efficiency (Chlorella sp., A. niger with the addition of 30 ml of distilled water, outdoors under static conditions after 48 h of the experiment) to 46.28% (Chlorella sp., A. niger with the addition of 30 ml of distilled water, on a shaker under laboratory conditions after 48 h of the experiment). For the purpose of analyzing the representation of functional groups in the microbial biomass and studying their interaction with the ash material, we used Fourier-transform infrared (FTIR) spectroscopy. We observed that the amount of Ni adsorbed positively correlates with absorbance in the spectral bands where we detect the vibrations of several organic functional groups. These groups include hydroxyl, aliphatic, carbonyl, carboxyl and amide structural units. The observed correlations indicate that, aside from polar and negatively charged groups, aliphatic or aromatic structures may also be involved in sorption processes due to electrostatic attraction. The correlation between absorbance and the Ni content reached a maximum in amide II band (r = 0.9; P < 0.001), where vibrations of the C=O, C–N, and N–H groups are detected. The presented results suggest that the simultaneous use of both microorganisms in biosorption represents an effective method for reducing Ni content in a solid substrate, which may be useful as a partial process for waste disposal.

Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

“…We conducted FTIR analyses to probe the potential chemical reactions between biomatter and cement (spectra presented in Figure f, main peak assignments listed in Table ). The functional groups of chlorella include the predominant O–H bonds (stretching peak at 3600–3000 cm –1 ), CO and C–O bonds in COOH (CO stretching peak at 1740–1730 cm –1 , C–O stretching peak at 1050–1020 cm –1 ), and protein-related groups (amide I band at 1600–1700 cm –1 from CO stretching and water O–H bending around 1640 cm –1 , amide II region from N–H bending and C–N stretching centered at 1540 cm –1 , and amide III vibrations of C–N stretching and N–H bending result in the weaker 1230–1240 cm –1 peaks). , In addition, we detect carbohydrate-related bands with multiple peaks (C–H stretching peak at 3000–2800 cm –1 , weak symmetric and asymmetric CH 3 , CH 2 , and C–H bending at 1375–1450 cm –1 from polysaccharides or lipids, C–O stretching peaks at 1075, 1095, and 1150 cm –1 , and C–C stretch from carbohydrates or alcohols at 1030 and 1050 cm –1 ). , …”

Effect of Algal Biomass on the Properties of Calcium Sulfoaluminate Cement

“…The results are presented in Figure . Various functional groups were observed, including CO in −COOH (1725 cm –1 ), CO stretch in ketone, and carbonyl acid (1650 cm –1 ), CC (1535 cm –1 ), and C–OH (1059 cm –1 ). ,,, Carboxyl and hydroxyl functional groups, among the identified structures, have been found to retard the OPC hydration. ,, …”

“…Various functional groups were observed, including C�O in −COOH (1725 cm −1 ), C�O stretch in ketone, and carbonyl acid (1650 cm −1 ), C� C (1535 cm −1 ), and C−OH (1059 cm −1 ). 13,17,20,28 Carboxyl and hydroxyl functional groups, among the identified structures, have been found to retard the OPC hydration. 13,29,30 Raw algae samples had significant peaks at 1725 and 1060 cm −1 which are attributed to the carboxyl and hydroxyl groups.…”

Multiple indicators metrological analysis for 5 kinds of tea produced in Yunnan, China

“…The heat of combustion (Libing et al, 2021), thermogravimetric parameters (Junfeng et al, 2021), fat contents (Novokshanova et al, 2019;Pauter et al, 2018), crude fiber contents (Oboh, 2006;Slama et al, 2019), ash contents (Hassid et al, 2022;Krishna et al, 2022;Šimonovičová et al, 2021), and contents of trace elements (Ohata et al, 2009;Vaculovič et al, 2011) for 5 kinds of tea were determined. According to the combustion heat, thermogravimetric parameters, fat contents, crude fiber contents, trace element contents and ash contents, the multi-index entropy method, gray pattern recognition and entropy cluster analysis of 5 kinds of tea were performed in Yunnan, China.…”