Tetracycline removal from aqueous solution by biochar derived from algae and modified with MnMoO4: effects of operating parameters, isotherm, kinetic, and thermodynamic study.

The aim of the present study is to improve the adsorption of tetracycline (TC) onto biochar of microalgae modified by nanocomposite of MnMoO4 (MM40BC60). The synthesized nanocomposite was characterized by Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area, Fourier transforms infrared (FTIR) spectroscopy to investigate the morphology, surface area, pores and the functional groups of MM40BC60, respectively. The effect of various parameters including initial pH, TC concentration, and temperature on the adsorption performance of TC to the adsorbent was evaluated with considering kinetics, isotherms, and thermodynamics models. The adsorption of TC on MM40BC60 shows good agreement with the pseudo-second-order kinetic and the Langmuir isotherm models. Results of the thermodynamic study showed that the adsorption process was a spontaneous and endothermic reaction in nature.

In the present research, a novel biocomposite that could efficiently remove tetracycline (TC) from wastewater was synthesized. The biocomposite was fabricated by biochar of microalgae (BC) and MnMoO₄ (MM) nanoparticles in different ratios to find a biocomposite with optimum characteristic as an efficient adsorbent. Finally, the optimum one was characterized to confirm its properties as an economical and efficient adsorbent for TC adsorption. Adsorption experiments including kinetic, isotherm and thermodynamic modeling were conducted to verify the high potential of novel biocomposite for TC adsorption. TC as an antibiotic frequently is found in soil, sediment, and aquatic environments which may lead to adverse side effects on human health including bacterial resistance and change in the microbial ecological functions. This makes the present study comprehensive and allows us to reach a strong conclusion on selecting biomaterial for biosorption purposes. Therefore, the present study will add unique knowledge to the science of biosorption.

Phytoremediation potential of vetiver grass irrigated with wastewater for treatment of metal contaminated soil.

A field experiment was conducted to understand the potential of vetiver grass (Vetiveria zizanioides) in heavy metal uptake from the soil and wastewater. Four main irrigation treatments including T1 (treated industrial wastewater), T2 (1:1 ratio of municipal:industrial wastewater), T3 (treated municipal wastewater) and T4 (fresh water) were applied. Moreover, the effect of arbuscular mycorrhizal fungus (AMF), Glomus mosseae, on plant growth and heavy metal concentration was evaluated. Three main criteria including bioconcentration factor (BCF), translocation factor (TF) and heavy metal uptake were applied to assess the potential of vetiver grass in accumulation and translocation of heavy metals to aerial parts. The highest concentration of heavy metals was found in plant and soil irrigated with T1 treatment followed by T2, T3 and the lowest concentrations were found in T4 treatment. Irrigation with treated municipal wastewater led to a significant increase in plant biomass and heavy metal uptake compared to other treatments. In T1 treatment (industrial wastewater), vetiver grass caused a significant decrease in Zn, Fe, Cu, Cd and Pb concentrations in soil as compared to no-plant treatment (without planting vetiver grass). Therefore, vetiver grass, irrigated with treated industrial wastewater, is a promising method for the development of urban and industrial green space.

Utilization of the microalga Scenedesmus quadricauda for hexavalent chromium bioremediation and biodiesel production.

The purpose of this study was to evaluate the bioremediation potential of the microalga Scenedesmus quadricauda in removing hexavalent chromium (Cr (VI)) from synthetic wastewater, under autotrophic and heterotrophic conditions and different inoculum concentrations. In both cultivation modes, the highest inoculum density of 0.8 g L-1 led to the highest Cr (VI) removal efficiency. In addition, Cr (VI) stress was more severe in 10 ppm compared to 5 ppm, while heavy metal effects were alleviated under heterotrophic conditions. Concurrently, Cr (VI) stress affected biomass quality, resulting in an increase in lipid and carbohydrate production and decreased proteins. Furthermore, under higher Cr (VI) concentration more saturated and monounsaturated fatty acids were produced, while monounsaturated fatty acids content was also greater under heterotrophic conditions. In total, the findings of this study highlight the advantages of heterotrophic cultivation of microalgae for concomitant industrial wastewater treatment and biofuel production.