Development of a loose powder sintering method for the preparation of porous ceramic from municipal solid waste incineration fly ash.

Loose powder sintering was used to prepare porous ceramic from municipal solid waste incineration fly ash (MSWI FA) and waste glass (WG). Sintering experiments at various temperatures, holding times, Al2O3 and SiC were conducted to investigate their effect on the ceramic properties and volatile heavy metal removal efficiency. The results show that increasing temperature from 1100 °C to 1250 °C promoted the transition of the mixtures from loose powder to a densified sintered matrix, with a bulk density increase of 31.10% and an open porosity decrease of 70.41%. The bulk density of the ceramic increased to 2.44 g/cm3 with 3% Al2O3 addition. The removal rates of Pb, Zn, Cu and Cd were higher than 90% at 1200 °C for 90 min, and promoted by the increasing temperature and holding time. Notably, 3% Al2O3 addition inhibited the volatilisation of Zn, Cu and Cd, particularly for Zn, the removal rate of which reduced to 61.66% at 1200 °C. The bulk density of the ceramic decreased to a minimum value of 1.48 g/cm3 with 4% SiC. The ratio of MSWI FA:WG:Al2O3:borax of 28.3:56.7:10:5 was proposed to obtain ceramic with a bulk density of 1.54 g/cm3 and a water absorption rate of 8.59% at 1150 °C. The leaching concentration of the porous ceramic met the Chinese regulatory standard (GB 8978-1996). Preparation of MSWI FA-based porous ceramics using the powder sintering method is a promising route for the harmless utilisation of MSWI FA. The porous ceramic is potentially applicable as a thermal-insulation building material.

Study on personalized microbial formulation during high-temperature aerobic fermentation of different types of food wastes.

The rapidly growing generation of food wastes has attracted extensive attention. In this context, biochemical processors, using high-temperature aerobic fermentation, has become a beneficial method to treat food waste in situ. However, existing microbial agents do not vary the proportion of strains according to the different food wastes, with this approach affecting the degradation efficiency. In this study, high-temperature resistant strains, with high degradation efficiency, were isolated and screened, before establishing a novel method for preparing personalized microbial formulations. Using the degradation efficiency of wastes after three days as the evaluation standard, 12 groups of Plackett-Burman experiments were used to determine the main effect strains for different types of food waste. Fifteen groups of Box-Behnken experiments were then used to determine their best proportions at which the maximum degradation efficiency occurred. Finally, simulated fermentation experiments were used to check for improvement of the fermentation process by mixing strains according to the personalized proportions. Results of molecular identification and physiological assessments indicated that all the seven strains were Bacillus spp., with no antagonistic effects between them. Based on the Plackett-Burman and Box-Behnken tests, three personalized bacterial agents were obtained for different types of food waste. The fermentation results further showed that, compared with the use of equal proportions of strains, a maximum increase of 15.43% in organic matter degradation was achieved after adding personalized proportions. This study provides both theoretical and practical references for the use of personalized microbial agent formulations for high-temperature aerobic fermentation of food wastes, thus providing these microbial agents with good prospects and economic value.

Investigation of the aerobic biochemical treatment of food waste: A case study in Zhejiang and Jiangsu provinces in China.

Food waste production is increasing rapidly and becoming a global concern. In areas with small production volumes and scattered production sources, the use of biochemical processors can be a beneficial supplement to the centralized treatment method for the in-situ treatment of wastes to effectively improve the efficiency of resource utilization. China is an important case study for this global issue; however, the implementation and outcomes of this process are not clear in China. In this study, field investigation and laboratory analysis were carried out on 14 biochemical processors in four representative regions of the Jiangsu and Zhejiang Provinces. The results showed that biochemical processors mostly used high-temperature aerobic fermentation, accounting for more than 80% of the commonly used procedures. The fermentation period was relatively short and ranged from 48 h to 10 days. Only 21.4% of devices were equipped with relatively complete secondary pollution-control units, which introduced the risk of secondary pollution during operation. The fermentation products exhibited common characteristics of acidity, high salt levels, and low maturity, rendering them unsuitable for agricultural use directly prior to an additional secondary fermentation process. Therefore, it is necessary to unify the design standards of biochemical processors and develop acid-resistant thermophilic microbial inoculants to increase fermentation efficiency. Thus, this study has significant implications in regulating food waste and serves as a theoretical and practical reference point to promote its in-situ treatment.

Flower-Shaped Mg3Al1-xFex-CO3 Layered Double Hydroxides Derived Adsorbents with Tunable Memory Effect for Environmental Remediation.

Herein, flower-shaped ternary layered double hydroxides (LDHs) Mg3Al1-xFex-CO3 with tunable memory effect as promising adsorbents was developed for the removal of acid red 88 anionic dye. All the samples were prepared using a co-precipitation method and were thoroughly characterized using several analytical techniques. The influence of Fe/(Al + Fe) ratio on the memory effect and dye adsorption capacity of Mg3Al1-xFex-CO3 LDHs was evaluated. Among all samples, Mg3Fe0.1Al0.9CO3 LDH resulted in the best adsorption capacity of 2709 mg/g in the first cycle. Comparing to Mg3Al1-CO3 and Mg3Fe1-CO3 LDHs, it also showed much better cycling performance during 4 cycles at 30 °C and atmospheric pressure. The influence of regeneration temperature was also investigated and found that 400 °C exhibit best performance. The detailed studies demonstrated that the adsorption capacity of Mg3Al1-CO3 can be improved by partially replacing Al by Fe.