Muhammad Rizwan

This study explores the bioremediation potential of indigenous industrial microalgal consortia for the simultaneous removal of ciprofloxacin (CIP) and nitrate from high-strength pharmaceutical wastewater. Native microalgae were isolated from effluent sources and cultivated in batch reactors for eight days under three conditions: pharmaceutical wastewater (WW), distilled water (DW), and nitrate-rich BG-11 medium. Remarkably, CIP removal reached 85% in WW, 70% in DW, and 57% in BG-11, demonstrating the consortia’s adaptability across different environments. In the BG-11 system, microalgae achieved 78% nitrate removal. However, elevated nitrate levels initially delayed CIP degradation, suggesting competitive interaction during uptake and metabolic processing. These findings reveal that native microalgal consortia can efficiently reduce pharmaceutical pollutants and nutrient loads without the need for genetic modification or external additives. This low-cost, eco-friendly approach offers promising prospects for integrating microalgae into tertiary treatment systems for pharmaceutical effluents, contributing to sustainable wastewater management and environmental protection.

Microalgae have been investigated for the production of different biofuels, and the feedstock is gaining interest in the present day due to their fast growth potential added to relatively high lipid, carbohydrate, and nutrient contents. The purpose of this study is to perform research to grow commercial microalgae and to produce a significant amount of lipid content from microalgae harvested as a viable alternative to renewable energy. The commercial microalga chosen is Chlorella sorokinian. Nitrogen is an essential element for microalgal growth, lipid synthesis, and several physiological processes. Microalgae can utilize several nitrogen sources, including nitrate and ammonium. The growth and lipid content of microalgae cultures and their biochemical structures are influenced by the type of nitrogen utilized, which is contingent upon the specific species of algae and the quantities and sources of nitrogen. This study aims to increase the growth and lipid accumulation of the microalga Chlorella sorokiniana by varying the nitrogen sources NaNO3, KNO3, and NH4Cl concentration in the culture medium. Results indicate that the highest cell density of 28.83 × 107 cell mL-1 and the maximum 4.1 g L-1 dry biomass were obtained under the treatment of sodium nitrate. Among nitrogen sources, the better pigment contents chl a 17.2 mg L-1 and chl. b contents were recorded in the case of sodium nitrate, followed by potassium nitrate and ammonium chloride. However, carbohydrate production was found to be a maximum of 390.1 μg mL-1 in ammonium chloride culture. The lipid content was measured using the Bligh and Dyer method and observed the highest 19% in sodium nitrate culture compared to other nitrogen sources. Overall, it can be concluded that sodium nitrate culture produced promising results regarding biomass production and different biochemical attributes.

Fluoride is an anionic pollutant found in surface or ground water in large quantities due to various human activities, for examples, disposal of industrial wastewater or geochemical reactions. The presence of fluoride in drinking water above certain limits has intense effects on human health. It strengthens the tooth enamel to a small level (1.0-1.5 mg/L). In drinking water, the presence of fluoride in the range of 1.5 to 4.0 mg/L may give rise to dental fluorosis at initial the stage, while the continuous exposure to high fluoride concentrations (4.0-10.0 mg/L) leads to skeletal fluorosis. In many countries of the world, including Pakistan, fluoride exists in ground water in high concentration, reaching above 30.0 mg/L on a large scale. The objective of writing this article is to offer accurate information on the efforts of a number of scholars who worked on fluoride removal from drinking water. The fluoride removal techniques have been categorized into two parts dealing with coagulation/precipitation and adsorption. Lime and alum (Nalgonda technique) and chitin have been discussed under coagulation technologies, while adsorption deals with a number of adsorbents, i.e., activated carbon, activated alumina, saw dust, bone char, rice husk ash, bauxite, tea-ash, and kaolin. Each technique discussed can remove fluoride under certain conditions. Each treatment technology has its limitations, and since there is no technology that can achieve its purpose in diverse conditions, the choice of fluoride removal techniques should be according to a specific site, depending on fundamental conditions and the needs of the local area.

Pharmaceutical active compounds (PACs) are under consideration due to their potential risk to human health and the ecosystem. Researchers are exploring economical and effective wastewater treatment methods to address these issues. Conventional wastewater treatment facilities cannot successfully remove PACs. The co-existence of several PACs and various microalgal species provides an opportunity for microalgae-based bioremediation of PACs. This review paper focuses primarily on antibacterial resistance genes (ARGS), removal of PACs through microalgal systems, essential factors influencing PACs removal, ecotoxicity of microalgae, bioprospecting strategy for microalgae, and challenges and future aspects for microalgae in PACs removal.

Arsenic (As) is a prominent carcinogen component produced via both geogenic and anthropogenic processes, posing serious risks to human health. This study aimed to investigate the potential of hydrochar prepared from red macroalgae for removing As from synthetic wastewater. The hydrochar was produced through 5 h hydrothermal carbonization (HTC) treatment at 200 °C, and then, chemically activated with ferric chloride hexahydrate (FeCl₃·6H₂O). SEM analysis revealed a permeable structure of hydrochar, while FTIR analysis detected the occurrence of several functional groups at the hydrochar interface. EDS analysis showed an increase in carbon concentration after FeCl₃·6H₂O activation. Hydrochar was then tested in batch experiments to investigate its As removal efficiency, with ICP-MS used to determine the levels of As after the adsorption process. The results showed that As removal efficiency increased with increasing initial As concentration from 50 to 250 mg/L, and the highest As removal efficiency was 84.75% at a pH of 6, initial concentration of 0.25 mg/L, and adsorbent dose of 1000 mg at 120 min. The Langmuir isotherm model supported the occurrence of homogeneous adsorption over the surface of hydrochar, while the pseudo-second-order model confirmed the chemisorptive nature of the process.

Eucalyptus wood is made up of lignocellulosic material; this lignocellulosic material contains two types of biopolymers, i.e., carbohydrate and aromatic polymers. In this study, this lignocellulosic material was used to prepare biochar. Three biochar, i.e., laboratory-based (B1), barrel-based (B2), and brick kiln-biochar (B3), were used for fluoride and arsenic removal from aqueous solution. Barrel-based biochar was prepared by using the two-barrel method’s alteration. The highest fluoride removal (99%) was attained at pH 2 in the presence of B1, while in the presence of B2 and B3, maximum fluoride removal was 90% and 45.7%, respectively. At pH 10, the maximum arsenic removal in the presence of B1, B2, and B3 was 96%, 94%, and 93%, respectively. The surface characteristics obtained by Fourier-transform infrared spectroscopy (FTIR) showed the presence of carbonyl group (C-O), and alkene (C=C) functional groups on all the three studied biochars. Isotherm studies showed that the adsorption was monolayered (all the adsorbed molecules were in contact with the surface layer of the adsorbent) as the Langmuir isotherm model best fits the obtained data. Adsorption kinetics was also performed. The R² value supports the pseudo-second-order kinetics, which means that chemisorption was involved in adsorbing fluoride and arsenic. It is concluded that B1 gives maximum removal for both fluoride (99%) and arsenic (96%). The study shows that lignocellulose-based biochar can be used for arsenic and fluoride removal from water.

The decline in fossil fuel reserves has forced researchers to seek out alternatives to fossil fuels. Microalgae are considered to be a promising feedstock for sustainable biofuel production. Previous studies have shown that urea is an important nitrogen source for cell growth and the lipid production of microalgae. The present study investigated the effect of different concentrations of urea combined with kelp waste extract on the biomass and lipid content of Chlorella sorokiniana. The results revealed that the highest cell density, 20.36 × 10⁷ cells⁻¹, and maximal dry biomass, 1.70 g/L, were achieved in the presence of 0.5 g/L of urea combined with 8% kelp waste extract. Similarly, the maximum chlorophyll a, b and beta carotenoid were 10.36 mg/L, 7.05, and 3.01 mg/L, respectively. The highest quantity of carbohydrate content, 290.51 µg/mL, was achieved in the presence of 0.2 g/L of urea and 8% kelp waste extract. The highest fluorescence intensity, 40.05 × 10⁷ cells⁻¹, and maximum total lipid content (30%) were achieved in the presence of 0.1 g/L of urea and 8% kelp waste extract. The current study suggests that the combination of urea and kelp waste extract is the best strategy to enhance the biomass and lipid content in Chlorella sorokiniana.