[Development of Zeolite Loaded Mg-La-Fe Ternary (hydr) oxides for Treatment of Low Concentration Phosphate Wastewater].

A novel Mg-La-Fe ternary (hydr)oxide magnetic zeolite adsorbent (MLFZ) was prepared using the hydrothermal method and employed for effective phosphate removal in this study. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicated that the MLFZ presented an amorphous surface with Mg, Fe, and La dispersed on the surface of the zeolite. The isothermal adsorption and kinetics results showed that the adsorption behavior of the MLFZ was consistent with that of the Langmuir isothermal model and quasi-second-order kinetics model. A relatively fast adsorption of phosphate with a short equilibrium time of 30 min was observed in the kinetics experiment, and the maximum adsorption capacity of the MLFZ was 13.46 mg·g-1 in the equilibrium adsorption isotherm study. The MLFZ showed effective adsorption performance over a wide pH range from 3.0 to 9.0. Moreover, the coexisting ions had an insignificant effect on phosphate adsorption. The MLFZ could easily be recovered using a magnet. After five adsorption-desorption cycles, the phosphate removal efficiency was maintained at approximately 90%. The FTIR, XPS, and Zeta potential analysis confirmed that the adsorption mechanisms were attributed to the surface deposition, electrostatic adsorption, and the inner complex formation by ligand exchange between lanthanum and phosphate. Furthermore, the MLFZ demonstrated high efficiency in scavenging phosphate from a natural pond (phosphate concentration decreased from 0.86 mg·L-1 to 0.013 mg·L-1), indicating that the MLFZ was an ideal material for phosphate management and treatment.

Phosphate removal from actual wastewater via La(OH)3-C3N4 adsorption: Performance, mechanisms and applicability.

In this study, La(OH)3 nanoparticles were immobilized on C3N4 to effectively restrict their aggregation and subsequently enhance the La utilization efficiency to promote phosphate adsorption. The prepared La(OH)3-C3N4 nanocomposite was characterized by SEM, XRD, FTIR, XPS, BET and Zeta potential analysis. Batch and continuously-fed (fixed-bed column) experiments to assess the adsorption performance of La(OH)3-C3N4 showed that the composite exhibits superior utilization efficiency, resulting to relatively quick adsorption with a short equilibrium time of 30 min. The theoretical maximum P adsorption capacity reached the 148.35 mg·g-1, efficiency that remained unaffected by the anions and HA present. The adsorption mechanism showed stability in a wide pH range (4.0-11.0) and is considered effective even after extensive use (five-cycles). The dynamics of the adsorption capacity and the half-penetration time values were estimated by 'Thomas' and 'Yoon-Nelson' models showed that are better represented from the experimental values obtained from the fixed-bed column trial. The adsorption mechanisms were attributed to surface precipitation, electrostatic attraction, and inner-sphere complexation via ligand exchange. Furthermore, La(OH)3-C3N4 demonstrated high efficiency in scavenging phosphate from both diluted and concentrated wastewater (natural pond and swine wastewater respectively). The above confirm that La(OH)3-C3N4 is a promising composite material for phosphate management in aqueous environments.

Exploring the effect of plant substrates on bacterial community structure in termite fungus-combs.

Fungus-cultivating termites are successful herbivores largely rely on the external symbiotic fungus-combs to decompose plant polysaccharides. The comb harbors both fungi and bacteria. However, the complementary roles and functions of the bacteria are out of the box. To this purpose, we look into different decomposition stages of fungus-combs using high-throughput sequencing of the 16S rRNA gene to examine bacterial community structure. We also explored the bacterial response to physicochemical indexes (such as moisture, ash content and organic matter) and plant substrates (leaves or branches or mix food). Some specific families such as Lachnospiraceae, Ruminococcaceae, and Peptostreptococcaceae may be involved in lignocellulose degradation, whereas Burkholderiaceae may be associated with aromatic compounds degradation. We observed that as the comb mature there is a shift of community composition which may be an adjustment of specific bacteria to deal with different lignocellulosic material. Our results indicated that threshold amount of physicochemical indexes are beneficial for bacterial diversity but too high moisture, low organic matter and high ash content may reduce their diversity. Furthermore, the average highest bacterial diversity was recorded from the comb built by branches followed by mix food and leaves. Besides, this study could help in the use of bacteria from the comb of fungus-cultivating termites in forestry and agricultural residues making them easier to digest as fodder.