Poly dimethyldiallylammonium chloride (PDMDAAC) was applied in a membrane bioreactor (MBR) to study its effects on mitigation of MBR membrane fouling. Floc size, zeta potential, soluble microbial substances (SMP) and extracellular polymeric substances (EPS) secretion were studied with respect to PDMMAAC-dosing operations. Results demonstrated that a sustainable filtration cycle extended 3.3 times with the optimal PDMDAAC dosage of 90 mg L. The addition of PDMDAAC could increase zeta potential of sludge floc, which led to the decrease in repulsive electrostatic interactions between flocs, as well as the facilitation of flocs-to-flocs aggregation. With the optimal dosage of PDMDAAC, the mean size of sludge was 3.23 ± 0.55 times higher than the control group, resulting in higher impact resistance and better adaptive capacity to the changing environment, which led to less SMP secretion. Moreover, a high contaminants removal rate was achieved in the reactor that was dosed with PDMDAAC. The average effluent concentrations of chemical oxygen demand and total nitrogen were less than 45.6 ± 2.85 and 5.23 ± 0.61 mg L, respectively, and the corresponding removal rates were 93.1 ± 5.81% and 89.1 ± 9.61%.

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This study used hexadecyl trimethyl ammonium bromide (CTAB) to organically modify orange peel biochar (OBC) to produce CTAB-modified orange peel biochar (NOBC), the adsorption performance of NOBC on Congo red dye in water and the influencing factors were investigated.

The oxidation of chloramphenicol (CAP) by potassium ferrate (VI) in test solution was studied in this paper. A series of jar tests were performed at bench scale with pH of 5-9 and molar ratio [VI/CAP] of 16.3:1-81.6:1. Results showed that raising VI dose could improve the treatment performance and the influence of solution pH was significant. VI is more reactive in neutral conditions, presenting the highest removal efficiency of CAP. The rate law for the oxidation of CAP by VI was first order with respect to each reactant, yielding an overall second-order reaction. Furthermore, five oxidation products were observed during CAP oxidation by VI. Results revealed that VI attacked the amide group of CAP, leading to the cleavage of the group, while benzene ring remained intact.

Membrane bioreactors (MBRs) are frequently used to treat municipal wastewater, but membrane fouling is still the main weakness of this technology. Additionally, the low carbon-nitrogen (C/N) ratio influent has been shown to not only increase the membrane fouling, but also introduce challenges to meet the effluent discharge standard for nitrogen removal. Herein, the authors addressed the challenges by adding cost-effective biochar. The results suggested that the biochar addition can enable membrane fouling alleviation and nitrogen removal improvement. The reduced membrane fouling can be ascribed to the biochar adsorption capacity, which facilitates to form bigger flocs with carbon skeleton in biochar as a core. As a result, the biochar addition significantly altered the mixed liquor suspension with soluble microbial product (SMP) concentration reduction of approximately 14%, lower SMP protein/polysaccharide ratio from 0.28 ± 0.02 to 0.22 ± 0.03, smaller SMP molecular weight and bigger sludge particle size from 67.68 ± 6.9 μm to 113.47 ± 4.8 μm. The nitrogen removal is also dramatically improved after biochar addition, which can be due to the initial carbon source release from biochar, and formation of aerobic–anaerobic microstructures. Microbial diversity analysis results suggested more accumulation of denitrification microbes including norank_f__JG30-KF-CM45 and Plasticicumulans. Less relative abundance of Aeromonas after biochar addition suggested less extracellular polymer substance (EPS) secretion and lower membrane fouling rate.

In recent years, coastal reclamation has become an important way for coastal areas to ease the contradiction between supply and demand along the land and to develop and utilize marine resources. However, large-scale coastal reclamation will change the original natural properties of the sea area and cause changes in the surrounding hydrodynamic environment. Although coastal geomorphic features have a non-negligible impact on tidal energy loss and disaster prevention, few studies have paid attention to the intrinsic connection between the complexity of coastal morphology and the rate of tidal reduction. In this study, Hangzhou Bay is selected as the research object, and a model based on the correlation between coastal geomorphic complexity and tidal energy reduction rate is constructed by using the fractal geometry theory and the quantitative evaluation method of landscape complexity, and the model is used in the assessment of the impacts of reclaimed land in Zhoushan Islands on the geomorphic complexity and tidal energy dissipation. The results of the study show that the differential tide reduction rate is highly correlated with the complexity of islands, shoreline irregularities, curved boundaries and spatial morphology. In the application of the model, it was found that the traditional planning and design of reclamation led to a dramatic change in shoreline morphology, and with the significant reduction of the number of subdimensions D and the shape index S, the differential tidal reduction rate would be reduced by more than 88%, which also poses a significant threat to coastal and downstream estuarine bay disaster prevention. Finally, based on the above analysis, effective control indexes and scientific reclamation measures are proposed to provide theoretical basis for the efficient utilization and protection of mudflats in China.

As an important part of the construction industry, rural residential buildings are characterized by low energy utilization, unreasonable structures and low consumption levels, and it is particularly important to study their low-carbon transformation and evaluation system. In view of the many low-carbon transformation needs of rural residential buildings, the existing research results were analyzed in depth, and the coefficient of variation method was used to identify the important factors affecting the low-carbon transformation of rural residential buildings, and the evaluation system of rural residential buildings’ low-carbon transformation was determined by Analytic Hierarchy Process (APH), and the system was used in a rural residential building low-carbon evaluation study. The results show that the influence of “energy use”, “envelope structure” and “economic factors” on the decarbonization of buildings is obvious, with the weights of 36.4%, 24.5% and 19.5% respectively. Among the secondary indicators, “clean energy utilization”, “electricity consumption”, “external wall insulation system” and “window performance” are the most important factors in reducing carbon emissions in rural areas. The most critical influencing factors for the low carbonization level of clean energy in rural residential buildings are “window performance”. Finally, based on the constructed low carbonization evaluation system, we propose a targeted solution strategy to provide a theoretical basis for the establishment of an effective low carbonization evaluation system for clean energy in rural residential buildings.

Coastal reclamation can provide new space for agriculture, industry and urbanization, as well as new investment opportunities in coastal areas. As a result, both the length and proportion of artificial shoreline increased significantly. Meanwhile, the complexity of coastal morphology will be diminished by large-scale land reclamation. Although coastal geomorphic characteristics has a crucial impact on tidal energy loss and disaster prevention, little research has been conducted on the relationship between the tidal range reduction rate and coastal morphological complexity. This relationship is essential for predicting the impact of coastal complexity changes caused by accelerated land reclamation on tidal energy loss. Taking Hangzhou Bay and Zhoushan Islands as the research objects, combined with fractal geometry theory and quantitative assessment method of landscape complexity, the correlation between coastal geomorphological complexity and tidal distance reduction rate is analyzed, and A model based on the correlation of the tidal range reduction rate and geomorphological complexity is established. The model is applied to evaluate the effect of reclamation in Zhoushan Islands on the landscape complexity and dissipation of tidal energy. The results show that the tidal range reduction rate is reduced with the decrease of fractal dimension and shape index, indicating that the coastal geomorphologic complexity has an important effect on tidal energy loss. The efficient control indicators and scientific reclamation measures are discussed in this paper. This study provides new ideas for the analysis of the comprehensive impact of reclamation on coastal geomorphic characteristics and disaster prevention, and can provide guidance for the efficient utilization and protection of tidal flats.