Bing Geng

The reuse of human wastes as biofertilizer resources offers a new option for meeting the growing demand for food and addressing poor soil productivity. Feces and black water are ubiquitous human wastes that usually require proper treatment, such as composting and anaerobic digestion, to remove potentially harmful substances before they can be applied as fertilizers. As an effective treatment technology for livestock farming wastes, the ectopic fermentation bed system (EFS) provides a new means of treating human waste and producing organic fertilizer from decomposed filler. Therefore, the objective of this study was to evaluate and compare the nutrient content and fertilizer potential of decomposed fillers obtained after EFS treatment of human feces and black water under different application conditions. The results showed that the application of fillers increased the yield of pakchoi by 3.60⁓29.32% and nutrient uptake by 8.09⁓83.45% compared to the CK, which could effectively promote the growth of pakchoi. This approach also improved the quality of pakchoi and enhanced soil fertility, and differences were observed in the effects of different kinds and application amounts of fillers. Soil EC was the soil property that had the greatest effect on the growth characteristics of pakchoi in this study. These findings help to better clarify the agronomic value of human wastes, but the effects of long-term filler application need to be further explored.

The reuse of human excreta as biofertilizer resources offers a new option for meeting the growing demand for food and addressing the scarcity of soil productivity. Feces and black water are two prevalent forms of human excreta, both of which contain potentially harmful substances and therefore need to be treated in an environmentally sound manner by appropriate means. Ectopic fermentation bed systems (EFSs) seem to be a new technique for effective human excreta management and the production of biofertilizers using decomposed fillers. Therefore, the objective of this study was to evaluate and compare the nutrient content and fertilizer potential of decomposed fills after treatment of human feces and black water by an EFS under different application conditions. The results showed that the application of an appropriate proportion of fillers was beneficial to promote the growth of pakchoi, improve the yield and quality of pakchoi, and enhance soil fertility. The safe production requirements of agricultural products can be met as long as a reasonable filler application rate is maintained, with human feces fillers controlled within 5% and black water fillers controlled within 10%. The main factors affecting the yield and quality of pakchoi in this study were soil properties, especially soil EC. These findings help to better clarify the agronomic value of human excreta; however, the effects of long-term filler application need to be further explored.

The discharge of aquaculture wastewater increased significantly in China. Especially, high content of nitrogen and phosphorus in wastewater could destroy the receiving water environment. To reduce the pollution of aquaculture wastewater, farmed triangle sail mussel (Hyriopsis cumingii) was proposed to be cultivated in the river. This was the first time that bacteria (Bacillus subtilis and Bacillus licheniformis) and microalgae (Chlorella vulgaris) were also used and complemented ecosystem functions. The pollutants in wastewater were assimilated by Chlorella vulgaris biomass, which was then removed through continuous filter-feeding of Hyriopsis cumingii. While, Bacillus subtilis and Bacillus licheniformis enhanced the digestive enzyme activities of mussel. It demonstrated that approximately 4 mussels/m³ was the optimal breeding density. Under such condition, orthogonal experiment indicated that the dose of Bacillus subtilis, Bacillus licheniformis, and Chlorella vulgaris should be 0.5, 1, and 2 mL respectively. Compared with mussel, mussel/microalgae, mussel/bacteria system, treatment ability of the mussel/microalgae/bacteria system in batch experiment was better, and 94.67% of NH₃-N, 92.89% of TP and 77.78% of COD were reduced after reaction for 6 days. Finally, 90 thousand mussels per hectare of water were cultivated in Kulv river in China, and the field experiment showed that water quality was significantly improved. After about 35 days of operation, NH₃-N, TN, TP and COD concentration were maintained around 0.3, 0.8, 0.3, and 30 mg/L respectively. Therefore, the mussel/microalgae /bacteria system in this study showed a sustainable and efficient characteristic of aquaculture wastewater bioremediation.

BACKGROUND: With the development of China’s livestock breeding industry, a large amount of waste was discharged and the local environment was seriously polluted. In this research, treatment performance of piggery waste in an ectopic fermentation system (EFS) using different padding materials and safety evaluation of generated organic fertilizer were studied in a pilot experiment.RESULTS: During the whole fermentation process, temperature in the EFS fluctuated with addition of fresh feces and its consumption, and the pH value varied between 6.5 and 9.5. The absorption coefficient of pig breeding wastewater and feces per kilogram of padding (maize straw) at the end was 2.52 and 1.88, respectively. Bacteria played a major role in decomposing organic matter, and its number was basically maintained at 10⁷–10⁸ orders of magnitude. The C:N ratio in two EFS beds decreased gradually and was below 14:1 at the end, indicating the maturity of fermentation. Moreover, operation of the EFS with addition of rice husk/coconut shell mixture was more stable than that of EFS with maize straw. After fermentation, the heavy metal, total nutrient content, ascaris egg mortality and fecal coliform population of the generated organic fertilizer from two fermentation beds all met the limits of the Organic Fertilizer Standard of China, and the seed germination index of the product increased.CONCLUSIONS: EFS employing maize straw or rice husk/coconut shell mixture as padding material can be used to treat both solid and liquid waste from pig farms. EFS technology reduced the biotoxicity of piggery waste. © 2022 Society of Chemical Industry (SCI).

The interaction between chrysene with humic acids (HA) was studied by the fluorescence spectroscopy. The results of fluorescence spectra revealed that chrysene could strongly quench the intrinsic fluorescence of HA through a static quenching procedure. The apparent binding constants K and number of binding sites n of chrysene with HA were 2.99 × 10⁵ and 1.0 which were obtained by the fluorescence quenching method. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) were negative, which indicated that the interaction of chrysene with HA was driven mainly by van der Waals forces and hydrogen bonds. The process of interaction was a spontaneous process in which Gibbs free energy change was negative. The results of three-dimensional fluorescence spectra showed that the chrysene entered into the hydrophobic cavities in some domain of HA.