Microalgae, in wet conditions, tend to grow on surfaces and form biofilms. The adhesion of microalgae to surfaces is very important for algal mass culture. The formation and development of microalgal biofims are in large denpend on the properties of cell surface, substratum surface and gowth medium. In this paper, the influence of substratum surface zeta potential on the microalgal biofilms was particularly investigated. We focused on a widely-used microalgal strain, the freshwater autotrophic Chlorella sp..The adhesion phenomena of Chlorella sp. to surfaces with different zeta potential were observed microscopically. It was found that Chlorella sp. adhered easily to the surface with a positive zeta potential and difficultly to the surface with a negative zeta potential. We concluded that the surface zeta potential had a greater influence on the adhesion of microalgal cells to substratum surfaces. Our findings have important implications for microalgae mass culture and harvesting.

The circular economy (CE) is a new development strategy for China to alleviate the contradiction between rapid economic growth and the shortage of raw materials and energy. As the basic material, steel is a key driver of the world's economy. Therefore, it is essential to set up CE indicators system to understand the mechanism of steel resources role in the circular economy. In this paper, a national level material flow evaluation framework based on CE theory is presented at the first. Then steel resources national lifetime cycle diagram is built based on dynamic Material Flow Analysis (MFA) method considering the steel lifetime circular flow characteristics. Under the guidance of this diagram, the material flow results of various stages (such as production process, fabrication & manufacturing process, in-use process, etc.) of steel lifetime cycle between 2001-2010 in China is obtained, including the end-of-life scarp amount of nine downstream industries. The results indicate that China steel resources has made gratifying achievements in improving productivity, reducing energy consumption and related pollution emission, but the degree of overall circulation remains to be improved urgently. In the end, a sketch of the future relevant policy recommendations are provided.

Thermodynamic analysis method for iron and steel manufacturing system is developed to describe the energy flow. The theoretical energy consumption for the manufacturing process is proposed to analyze the energy-saving potential. Energy balance based on enthalpy with a uniform reference state is established to analyze the amounts and forms of energy flow in the manufacturing system. The energy-saving potential of blast furnace system is discussed to choose the appropriate energy-saving methods and technologies.

According to the technical demand of hot-rolling production in steel plant, a production scheduling mathematical model was proposed with the aim of reducing the production cost and optimizing the product quality. The scheduling of reheating furnaces which was summed up as the Boolean satisfiability problem was involved in rolling scheduling optimization which was summed up as the multiple traveling salesman problem with uncertain traveling salesman number, and a two-stage genetic-tabu algorithm was designed to solve the problem. It was shown that, the model could fully meet the demand of hot-rolling production. Compared to the human-computer method, the results had better performance on high production and energy efficiency.

Rheological properties of microalgae suspensions affect the mixing and mass transport in photobioreactor systems and the design of downstream biomass processing technologies，and directly impact the energy demand and system performance of algae biofuel production. The purpose of this paper is to obtain the rheological properties as a function of volume fraction. The volume fractions of microalgae suspensions φ were derived according to the size distribution of the microalgae cells and cell number concentrations per cubic meter liquid. We found that at low concentrations, microalgae suspensions display a Newtonian fluid behavior. At high concentrations, microalgae suspensions behave as a shear thinning non-Newtonian fluid. The results are of potential scientific relevance and also useful in relation to the design of algae bioprocessing for the large scale production of economic biofuels.