Hexavalent chromium Cr (VI) is a toxic heavy metal that discharged by many industries into the water streams. It is the most poisoned form of chromium compounds that destroy the ecosystem. Microalgal species, Chlorella sp., was used as a biosorbent material to remove Cr (VI) from the Cr-contaminated effluents. Furthermore, different variables: pH, temperature, contact time, Cr (VI) concentration and algal dose were optimized in order to determine the optimum conditions that achieve the highest removal efficiency. Optimization process was achieved through two steps: one factor at a time (OFAT) experiments followed by 2⁵ general full factorial. Moreover, molecular identification was performed using 18S rRNA in order to demonstrate the species of Chlorella and it was identified as Chlorella sorokiniana. The highest chromium removal efficiency of 99.6793% was achieved at 100 ppm Cr (VI) after three days contact time. Chlorophyll ‘a’ estimation as a growth indicator stated that Chlorella sorokiniana can tolerate 100 ppm Cr (VI) for three days exposure. The results suggested that Chlorella sorokiniana is a good biosorbent material and it distinguished by its high ability to uptake Cr (VI) from solutions.

Biosorption is a bioremediation approach for the removal of harmful dyes from industrial effluents using biological materials. This study investigated Methylene blue (M. blue) and Congo red (C. red) biosorption from model aqueous solutions by two marine macro-algae, Ulva fasciata and Sargassum dentifolium, incorporated within acrylic fiber waste to form composite membranes, Acrylic fiber-U. fasciata (AF-U) and Acrylic fiber-S. dentifolium (AF-S), respectively. The adsorption process was designed to more easily achieve the 3R process, i.e., removal, recovery, and reuse. The process of optimization was implemented through one factor at a time (OFAT) experiments, followed by a factorial design experiment to achieve the highest dye removal efficiency. Furthermore, isotherm and kinetics studies were undertaken to determine the reaction nature. FT-IR and SEM analyses were performed to investigate the properties of the membrane. The AF-U membrane showed a significant dye removal efficiency, of 88.9% for 100 ppm M. blue conc. and 79.6% for 50 ppm C. red conc. after 240 min sorption time. AF-S recorded a sorption capacity of 82.1% for 100 ppm M. blue conc. after 30 min sorption time and 85% for 100 ppm C. red conc. after 240 min contact time. The membranes were successfully applied in the 3Rs process, in which it was found that the membranes could be used for five cycles of the removal process with stable efficiency.

Dyes are a type of pollutant that have been discharged into water streams by various industries and had harmful effects on the environment and human health. Therefore, present work was directed to recycle acrylic fibers waste to be used as an adsorbent to exclude dyes such as methylene blue (MB) and Congo red (CR) from dyes-polluted wastewater. Acrylic fibers waste was converted into membrane followed by chemical grafting with p-phenylenediamine monomer to form functional modified membranes. Afterwards, some characterization analyses; Fourier transform-infrared, scanning electron microscope, swelling behavior, and porosity properties were performed for the acrylic fiber grafted membrane (AFGM). For obtaining the best conditions that permit the highest adsorption capacity of the AFGM, some preliminary experiments followed by general full factorial design experiments were displayed. Langmuir, Freundlich isotherms and kinetic studies evaluations were applied. Results revealed that, the adsorption capacities of the AFGM were 61% for Methylene blue and 86% for Congo red that stated the high affinity of the AFGM to the anionic dyes. The reusability of the AFGM membranes in different cycles for 3Rs processes “Removal, Recovery, and Re-use” indicated the efficiency of the AFGM to be used in wastewater treatment.

The bio-sorption is the using of biological biomasses, live or dead form, for heavy metals removal from polluted wastewater. In the current work, live planktonic Nostoc sp. cells were used for hexavalent Chromium [Cr(VI)] elimination from Cr-contaminated wastewater. Optimisation process was achieved in order to obtain the optimum conditions that help achieving the highest Cr(VI) removal efficiency. For instance, One Factor At a Time ‘OFAT’ experiments were performed for the determination of the coded factors levels (low/high levels) that can be included in the Full factorial design experiment ‘many interacted factors at a time’. Afterwards, a small reactor design was implemented to develop Nostoc sp. algal biofilm. After that, the algal biofilm was applied in the Cr(VI) removal process to facilitate harvesting and dewatering of the biomass after the treatment process. Results showed that, live planktonic Nostoc sp. achieved the highest Cr(VI) removal efficiency of 98.16%at 100 ppm after 7 days contact time. Furthermore, Nostoc sp. stated its great ability to form a biofilm on polystyrene substrate which achieved the highest Cr(VI) removal of ‘86.498%’ at a concentration of 100 ppm after 7 days contact time. Some characterisation techniques such as Fourier Transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analyses were applied on the developed biofilm of Nostoc sp. Isotherm and kinetics were investigated for the Cr(VI) removal process using Nostoc sp. biofilm.