Immobilized Algae for Produced Water Treatment and Desalination

Produced water (PW) is the effluent generated during oil mining and extraction. On average, for every barrel of oil, 4-5 barrels of PW are generated worldwide. The presence of various contaminants in PW makes it toxic. Disposal of untreated PW into oceans and water bodies can cause adverse effects on human health and the environment. Taking into account the large volumes of it being generated, and its effects on the environment, proper treatment is required before reuse or disposal. Microalgal treatment is an effective method for the bioremediation and biodesalination of produced water when acclimatized algal biomass is used for the treatment. However, harvesting this acclimatized high-value algal biomass for reuse and recycling, and the reuse or disposal of produced water is challenging. Thus, the immobilization of microalgae into polymer matrices will be beneficial in solving both problems. Different polymers, both natural and synthetic are used as matrices for immobilizing cells. In this study, experiments were done with alginate and chitosan matrices to immobilize algae. Microalgae enriched and grown in wastewater were acclimatized to three different produced water samples by progressive adaptation in a steadily increasing ratio of produced water. The algae which could adapt and grow in the highest ratio in minimum time were immobilized and used for bioremediation of produced water. The study also evaluated the stability of the matrix in produced water and the treatment efficiency. The results of the study led to the conclusion that produced water is highly toxic for the stability of alginate and chitosan matrices. A more stable matrix has to be determined and experimented with for immobilizing algae and treatment of produced water

Nitrate Removal from Groundwater Using Immobilized Heterotrophic Algae

The treatment efficiency of Chlorella sorokiniana and Scenedesmus species, immobilized in sodium alginate, was evaluated for removing nitrate from groundwater. The experiments were performed initially in batch mode and the best-performing conditions were replicated in sequencing batch reactor mode. S. sp. showed a higher nitrate uptake in short term than C. sorokiniana. Immobilized S. sp. and C. sorokiniana cells showed 90% nitrate removal in 9 and 12 days, respectively. The optimal ratio of algal beads/water was found to be 12.5% (v:v). Comparatively, suspended S. sp. cells were able to remove only up to 35% of nitrate in 8 days. Alginate immobilized S. sp. beads were capable of uptaking nitrate for 100 consecutive days in sequencing batch reactor mode. When tested in actual groundwater, 90% of nitrate was eliminated in 2 days without need for any additional carbon source. Immobilized algal beads can be a low-cost alternative technique to remove nitrate from groundwater as they are water-insoluble, non-toxic, easy to harvest, and offer high removal efficiency. Highlights: Utilization of immobilized algae is a practical method for nitrate treatment. • Cultivation of heterotrophic algae reduces retention time needed for treatment. • Actual groundwater is more suitable for nitrate removal than simulated lab water. • In natural water, additional carbon source is not required for successful removal. • Same algae beads could be reused for treatment for repeated cycles up to 100 days. Includes supplementary materials

Role of Fungal Biomass in N-Hexane Biofiltration

The biofiltration of n-hexane is studied to optimize determinants factors of hydrophobic VOC filtration efficiency. Four trickle-bed air biofilters (TBABs) were employed; two of which were supplied with nutrients buffered at a neutral pH, while another two at an acidic pH of 4 to induce and enhance fungal growth. The loading rate of n-hexane was kept constant in all TBABs at 13 g/m3/h. At each pH levels studied, the biomass of the TBABs was pre-acclimated using different ratios of n-hexane and methanol. The fungal biomass responsible for the degradation of n-hexane was then examined and quantified. Dichloran Rose Bengal Chloramphenicol agar was used for fungi quantification, and optical microscopy for classification. Effluent biomass was validated by measuring volatile suspended solids. Fungal counts resulting from n-hexane biodegradation were related to nitrate and carbon consumption. It was found that n-hexane elimination capacity closely followed biomass growth, and reached a steady-state at an optimum biomass density of roughly 3000 cfu/ml. Major shifts in fungal species were observed in all TBABs. Dominant fungal species grew slowly to become the most numerous, and were found to provide maximum elimination capacity, although TBABs pre-acclimated to higher methanol concentrations took less time to reach this steady-state. It was concluded, therefore, that steady and monitored growth of TBAB biomass is an essential factor in maximizing fungi’s ability to metabolize VOCs and that a new ecological biofiltration model may be the most effective at VOC purification

Chemistry of Substituted Thiazinanes and Their Derivatives

Thiazinanes and its isomeric forms represent one of the most important heterocyclic compounds, and their derivatives represented a highly potent drug in disease treatment such as, 1,1-dioxido-1,2-thiazinan-1,6-naphthyridine, which has been shown to have anti-HIV activity by a mechanism that should work as anti-AIDS treatment, while (Z)-methyl 3-(naphthalen-1-ylimino)- 2-thia-4-azaspiro[5 5]undecane-4-carbodithioate showed analgesic activity, cephradine was used as antibiotic and chlormezanone was utilized as anticoagulants. All publications were interested in the chemistry of thiazine (partially or fully unsaturated heterocyclic six-membered ring containing nitrogen and sulfur), but no one was dealing with thiazinane itself which encouraged us to shed new light on these interesting heterocycles. This review was focused on the synthetic approaches of thiazinane derivatives and their chemical reactivity

Chemistry and Biological Activities of 1,2,4-Triazolethiones—Antiviral and Anti-Infective Drugs

Mercapto-substituted 1,2,4-triazoles are very interesting compounds as they play an important role in chemopreventive and chemotherapeutic effects on cancer. In recent decades, literature has been enriched with sulfur- and nitrogen-containing heterocycles which are used as a basic nucleus of different heterocyclic compounds with various biological applications in medicine and also occupy a huge part of natural products. Therefore, we shed, herein, more light on the synthesis of this interesting class and its application as a biologically active moiety. They might also be suitable as antiviral and anti-infective drugs

Recent updates on ions and nutrients uptake by halotolerant freshwater and marine microalgae in conditions of high salinity

Algae is an appropriate natural resource to augment the optimal use of undesired ions in water and wastewater. Increasing algal cells, the consumption of particular ions, including chloride, nitrate, phosphate, and ammonium, provides a suitable way to optimize water treatment processes. Different algal species have the capability to survive in extreme salinities by developing resistance against osmotic pressure in saline water. The current study reviews the effect of salinity on algal biomass production, algal growth rate, chlorides, nitrates, phosphates, chemical oxygen demand (COD), total nitrogen, total phosphorus, and ammonium ions. Mainly algae cultivated in freshwater, synthetic brackish water, seawater, and hypersaline water, were studied for this review. Various ion uptake mechanisms used by the algal cell are summarized, focusing on biosorption and bioaccumulation processes. Critical parameters such as light intensity, pH, and temperature variations significantly influence ion and nutrients uptake efficiencies. Analysis performed on collected data indicated that halophytic algae could survive in high salinities at elevated growth rates compared to freshwater. The halotolerant algal species showed an inclining trend of chloride ion removal with an elimination capacity of 7.5 g.m-3.h-1. Moreover, the nitrate uptake rate in halophytic algae is 10-folds higher to phosphate, regardless of salinity level. It could be concluded that microalgae will be beneficial for ion and nutrient uptake processes in treating high saline water

Selective Oxidation Using Flame Aerosol Synthesized Iron and Vanadium-Doped Nano-TiO 2

Selective photocatalytic oxidation of 1-phenyl ethanol to acetophenone using titanium dioxide (TiO2) raw and doped with Fe or V, prepared by flame aerosol deposition method, was investigated. The effects of metal doping on crystal phase and morphology of the synthesized nanostructured TiO2 were analyzed using XRD, TEM, Raman spectroscopy, and BET nitrogen adsorbed surface area measurement. The increase in the concentration of V and Fe reduced the crystalline structure and the anatase-to-rutile ratios of the synthesized TiO2. Synthesized TiO2 became fine amorphous powder as the Fe and V concentrations were increased to 3 and 5%, respectively. Doping V and Fe to TiO2 synthesized by the flame aerosol increased photocatalytic activity by 6 folds and 2.5 folds, respectively, compared to that of pure TiO2. It was found that an optimal doping concentration for Fe and V were 0.5% and 3%, respectively. The type and concentration of the metal dopants and the method used to add the dopant to the TiO2 are critical parameters for enhancing the activity of the resulting photocatalyst. The effects of solvents on the photocatalytic reaction were also investigated by using both water and acetonitrile as the reaction medium

Comparative Study on the Performance of Anaerobic and Aerobic Biotrickling Filter for Removal of Chloroform

Use of biotrickling filter (BTF) for gas phase treatment of volatile trihalomethanes (THMs) stripped from water treatment plants could be an attractive treatment option. The aim of this study is to use laboratory-scale anaerobic BTF to treat gaseous chloroform (recalcitrant to biological transformation) as a model THM and compare results with aerobic BTF. Additional investigations were conducted to determine the microbial diversity present within the BTFs. Chloroform is a hydrophobic volatile THM known to be difficult to biodegrade. To improve the degradation process, ethanol was used as a cometabolite at a different ratio to chloroform. The experimental plan was designed to operate one BTF under anaerobic condition and the other one under aerobic acidic condition. Higher elimination capacity (EC) of 0.23 ± 0.01 g/[m3·h] was observed with a removal efficiency of 80.9% ± 4% for the aerobic BTF operating at pH 4 for the concentration ratio of 1:40 chloroform to ethanol. For similar ratio, the anaerobic BTF supported lower removal efficiency of 59% ± 10% with corresponding lower EC of 0.16 ± 0.01 g/[m3·h]. Carbon recovery acquired for anaerobic and aerobic BTFs was 59% and 63%, respectively. The loading rate for chloroform on both BTFs was 0.27 g/[m3·h] (per m3 of filter bed volume). Variations of the microbial community were attributed to degradation of chloroform in each BTF. Azospira oryzae and Azospira restrica were the dominant bacteria and potential candidates for chloroform degradation for the anaerobic BTF, whereas Fusarium sp. and Fusarium solani were the dominant fungi and potential candidates for chloroform degradation in the aerobic BTF

Synthesis and crystallographic evaluation of diazenyl- and hydrazothiazoles. [5.5] sigmatropic rearrangement and formation of thiazolium bromide dihydrate derivatives

In this investigation the synthesis of diazenylthiazoles (3a-e) by the reaction of arylthiosemicarbazides with omega-bromoacetophenones via Eschenmoser-coupling reaction in acetonitrile and equimolar amounts of triethylamine and triphenylphosphine. Upon heating 1,4-disubstituted thiosemicarbazides with omega-bromoacetophenones in absolute ethanol, hydrazothiazoles (16a-i) were precipitated. On the other hand, the reaction of arylthiosemicarbazides with omega-bromoacetophenones in refluxing ethanol yielded 2-amino-5-[4-aminophenyl]-4-phenylthiazolium bromide dihydrate derivatives (19a-g) via [5.5] sigmatropic shift. The studied products were further characterized by IR, H-1 NMR, C-13 NMR and mass spectrometry. X-ray single crystal of 3a and 16h showed that, the molecules crystallized in the triclinic crystal system, space group P2(1)/c. Whereas the X-ray single crystal of 19b showed the molecule crystalized in orthorhombic, space group P2(1)2(1)2(1). In the crystal of 19b, the lattice water and bromide ion associated through hydrogen bonded with thiazole-NH2. (C) 2018 Published by Elsevier B.V.Peer reviewe

Eschenmoser-Coupling Reaction Furnishes Diazenyl-1,2,4-triazole-5(4H)-thione Derivatives

Diazenyl 1,2,4-triazol-5(4H)-thione derivatives were synthesized in good yields via Eschenmoser-coupling reaction and nucleophilic attack between 1,4-disubstituted thiosemicarbazides and 2,3,5,6-tetrachloro-1,4-benzoquinone (p-CHL). The structure of the synthesized compounds was confirmed by IR, NMR and mass spectral data as well as single crystal X-ray analysis.Peer reviewe