Diatomite precoat filtration for wastewater treatment: Filtration performance and pollution mechanisms

Progress in the Sustainable Development of Biobased (Nano)materials for Application in Water Treatment Technologies

Water pollution remains a widespread problem, affecting the health and wellbeing of people around the globe. While current advancements in wastewater treatment and desalination show promise, there are still challenges that need to be overcome to make these technologies commercially viable. Nanotechnology plays a pivotal role in water purification and desalination processes today. However, the release of nanoparticles (NPs) into the environment without proper safeguards can lead to both physical and chemical toxicity. Moreover, many methods of NP synthesis are expensive and not environmentally sustainable. The utilization of biomass as a source for the production of NPs has the potential to mitigate issues pertaining to cost, sustainability, and pollution. The utilization of biobased nanomaterials (bio-NMs) sourced from biomass has garnered attention in the field of water purification due to their cost-effectiveness, biocompatibility, and biodegradability. Several research studies have been conducted to efficiently produce NPs (both inorganic and organic) from biomass for applications in wastewater treatment. Biosynthesized materials such as zinc oxide NPs, phytogenic magnetic NPs, biopolymer-coated metal NPs, cellulose nanocrystals, and silver NPs, among others, have demonstrated efficacy in enhancing the process of water purification. The utilization of environmentally friendly NPs presents a viable option for enhancing the efficiency and sustainability of water pollution eradication. The present review delves into the topic of biomass, its origins, and the methods by which it can be transformed into NPs utilizing an environmentally sustainable approach. The present study will examine the utilization of greener NPs in contemporary wastewater and desalination technologies.

Bismuth-Based Z-Scheme Heterojunction Photocatalysts for Remediation of Contaminated Water

Agricultural runoff, fuel spillages, urbanization, hospitalization, and industrialization are some of the serious problems currently facing the world. In particular, byproducts that are hazardous to the ecosystem have the potential to mix with water used for drinking. Over the last three decades, various techniques, including biodegradation, advanced oxidation processes (AOPs), (e.g., photocatalysis, photo-Fenton oxidation, Fenton-like oxidation, and electrochemical oxidation process adsorption), filtration, and adsorption techniques, have been developed to remove hazardous byproducts. Among those, AOPs, photocatalysis has received special attention from the scientific community because of its unusual properties at the nanoscale and its layered structure. Recently, bismuth based semiconductor (BBSc) photocatalysts have played an important role in solving global energy demand and environmental pollution problems. In particular, bismuth-based Z-scheme heterojunction (BBZSH) is considered the best alternative route to overhaul the limitations of single-component BBSc photocatalysts. This work aims to review recent studies on a new type of BBZSH photocatalysts for the treatment of contaminated water. The general overview of the synthesis methods, efficiency-enhancing strategies, classifications of BBSc and Z-scheme heterojunctions, the degradation mechanisms of Z- and S-schemes, and the application of BBZSH photocatalysts for the degradation of organic dyes, antibiotics, aromatics compounds, endocrine-disrupting compounds, and volatile organic compounds are reviewed. Finally, challenges and the future perspective of BBZSH photocatalysts are discussed.

Clay-Alginate Beads Loaded with Ionic Liquids: Potential Adsorbents for the Efficient Extraction of Oil from Produced Water

Produced water (PW) generated from the petroleum industry, during the extraction of oil and gas, has harmful impacts on human health and aquatic life, due to its complex nature. Therefore, it is necessary to treat it before discharging it into the environment in order to avoid serious environmental concerns. In this research, oil adsorption from PW was investigated using clay-alginate beads loaded with ionic liquids (ILs), as the adsorbent material. The effects of several process parameters, such as the initial concentration of oil, contact time, pH, and temperature on the removal efficiency of the beads, were analyzed and optimized. Different characterization methods, such as the Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and thermal gravimetric analysis (TGA), were used to investigate the surface morphology, the chemical bond structure and functional group, and the thermal stability of the ILs-based beads. The results revealed that the clay-alginate-ILs beads indicated a removal efficiency of 71.8% at the optimum conditions (600 ppm initial oil concentration, 70 min contact time, 10 pH, and at room temperature) with an adsorption capacity of 431 mg/g. The FTIR analysis confirmed the successful chemical bond interaction of the oil with the beads. The SEM analysis verified that the beads have a porous and rough surface, which is appropriate for the adsorption of oil onto the bead’s surface. The TGA analysis provides the thermal degradation profile for the clay-alginate-ILs. The beads used in the adsorption process were regenerated and used for up to four cycles.

Diatom Frustule Array for Flow-Through Enhancement of Fluorescent Signal in a Microfluidic Chip

Diatom frustules are a type of natural biomaterials that feature regular shape and intricate hierarchical micro/nano structures. They have shown excellent performance in biosensing, yet few studies have been performed on flow-through detection. In this study, diatom frustules were patterned into step-through holes and bonded with silicon substrate to form an open-ended filtration array. Then they were fixed into a microfluidic chip with a smartphone-based POCT. Human IgG and FITC-labeled goat–anti-human IgG were adopted to investigate the adsorption enhancement when analyte flowed through diatom frustules. The results indicated up to 16-fold enhancement of fluorescent signal sensitivity for the flow-through mode compared with flow-over mode, at a low concentration of 10.0 μg/mL. Moreover, the maximum flow rate reached 2.0 μL/s, which resulted in a significant decrease in the testing time in POCT. The adsorption simulation results of diatom array embedded in the microchannel shows good agreement with experimental results, which further proves the filtration enrichment effect of the diatom array. The methods put forward in this study may open a new window for the application of diatom frustules in biosensing platforms.

Pathways and mechanisms of nitrogen transformation during co-composting of pig manure and diatomite

The aim of this study was to investigate the pathways and mechanisms of nitrogen transformation during the composting process, by adding diatomite (0%, 2.5%, 5%, 10%, 15% and 20%) into initial mixtures of pig manure and sawdust. The results revealed that diatomite facilitated the conversion from NH₄⁺-N to amino acid nitrogen and hydrolysis undefined nitrogen, then reduced NH₃ and N₂O emission by 8.63-35.29% and 14.34-73.21%, respectively. Moreover, the structure and abundance of nitrogen functional genes provided evidence for nitrogen loss. Furthermore, compared with the control (0.03), the treatment blended with 10% diatomite (T3) had the highest value in composting score (-1.27). Additionally, the ratio of carbon and nitrogen (57.30%) was vital for reducing nitrogen loss among all physio-chemical parameters in this study. In conclusion, adding diatomite was a practical way to enhance nitrogen conservation and increase quality of end products, and the optimum added dosage was at 10%.

Application of diatomite for gallic acid removal from molasses wastewater

In this study, diatomite was refined by a simple purification method consisting of calcination combined with acid washing. Optimal purification conditions were the focus, including the influence of conditions on diatomite morphology, structure, and specific surface area. The results showed that the optimal conditions were a 550 °C carbonization temperature and 25 wt% HCl. This purified diatomite was then employed to adsorb gallic acid (GA) from molasses wastewater in a series of adsorption experiments, which illustrated that (ḭ) GA adsorption fitted a pseudo-second-order model and the Freundlich equation better with GA adsorption by purified diatomite; (ḭḭ) the adsorption process was physical, nonspontaneous, and endothermic; (ḭḭḭ) the maximum GA adsorption capacity by purified diatomite was 19.852 mg g^-1. This study reported the examination of a promising material for sugar mill wastewater pretreatment.

A new method to recover L-tyrosine from E. coli fermentation broth

Although the production of L-tyrosine by recombinant Escherichia coli has been widely reported, L-tyrosine recovery from the fermentation broth has been rarely reported. Methods to recover L-tyrosine from the broth after alkaline lysis of the bacterial cells have been described. However, the broth becomes viscous and dark following cell lysis, making further extraction and purification difficult. Here, a new method for L-tyrosine extraction and purification from the fermentation broth without the lysis of bacteria is reported. First, acids, rather than bases, were used to dissolve L-tyrosine in the broth without causing lysis of the bacterial cells. E. coli cells in the broth were then removed through centrifugation. Activated carbon was then used to decolorize the supernatant containing L-tyrosine. Finally, sodium hydroxide was added to the clarified L-tyrosine solution for isoelectrocrystallization. L-tyrosine was obtained after filtration and drying. The recovery yield of L-tyrosine was 92%, and the purity was >98.5%, indicating high efficiency of the new method of L-tyrosine recovery from fermented broth. Furthermore, the method provides a reference for the extraction of guanosine, inosine, hypoxanthine, and other biological fermentation products.

A Critical Review on Metal-Organic Frameworks and Their Composites as Advanced Materials for Adsorption and Photocatalytic Degradation of Emerging Organic Pollutants from Wastewater

Water-borne emerging pollutants are among the greatest concern of our modern society. Many of these pollutants are categorized as endocrine disruptors due to their environmental toxicities. They are harmful to humans, aquatic animals, and plants, to the larger extent, destroying the ecosystem. Thus, effective environmental remediations of these pollutants became necessary. Among the various remediation techniques, adsorption and photocatalytic degradation have been single out as the most promising. This review is devoted to the compilations and analysis of the role of metal-organic frameworks (MOFs) and their composites as potential materials for such applications. Emerging organic pollutants, like dyes, herbicides, pesticides, pharmaceutical products, phenols, polycyclic aromatic hydrocarbons, and perfluorinated alkyl substances, have been extensively studied. Important parameters that affect these processes, such as surface area, bandgap, percentage removal, equilibrium time, adsorption capacity, and recyclability, are documented. Finally, we paint the current scenario and challenges that need to be addressed for MOFs and their composites to be exploited for commercial applications.

Characterization of Diatomaceous Earth and Halloysite Resources of Poland

The mining industry of Poland is based mostly on coal and copper ores. Strict carbon emissions and the depletion of deposits will slowly phase out coal. Therefore, metallic ores and other mineral raw materials will dominate the extractive industry of Poland. Current measured resources of the largest deposits of halloysite and diatomaceous earth in Poland are over 0.5 Mt and 10 Mt, respectively. Halloysite and diatomaceous earth samples from halloysite Dunino deposits and Jawornik diatomaceous earth deposits (composed mostly of diatomaceous skeletons (frustules)) were subjected to mineralogical analysis, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS) nanostructural, chemical, elemental, and mineral content analysis. Both these minerals have similar properties, i.e., sorption capacity and cation exchange capacity, and are used mostly for the same purposes, e.g., adsorbents, filler material, and filtration. Samples of Dunino halloysite consist of minerals such as halloysite, kaolinite, hematite, magnetite, quartz, magnesioferrite, rutile, ilmenite, geikielite, goyazite, gorceixite, and crandallite, with little impurities in the form of iron oxides. Occasionally, halloysite nanoplates (HNP) nanotubes (HNT) were found. Diatomaceous earth is composed mainly of silica-containing phases (quartz, opal) and clay minerals (illite and kaolinite). The frustules of diatoms are mostly centric (discoid) and have radius values of approximately 50–60 μm. Large resources of these minerals could be used in the future either for manufacturing composite materials or highly advanced adsorbents.

Improvement of cleaner composting production by adding Diatomite: From the nitrogen conservation and greenhouse gas emission

In order to investigate the improvement of Diatomite (DM) on the production of cleaner composting, reflected by emission of NH₃ and greenhouse gases (GHGs), three dosages of DM (0%, 5% and 10%) were added into mixture of pig manure and sawdust for 42 days composting. Addition of DM promoted the transformation of organic matter and improved the quality of end product. Meanwhile, it was confirmed by the increase of NO₃^--N formation and nitrogen conservation. Besides, adding DM aided on reducing emission of CH₄, N₂O and NH₃ by 18.27%-30.41%, 26.89%-84.16% and 10.41%-23.70%, respectively. Furthermore, the DM had a positive effect on the maturity of compost products, reflecting by GI value and HA/FA. Consequently, through the factor analysis, 10% was suggested to improve the quality of end product and reduce nitrogen loss as well as GHGs emission.