The Influence of Two Natural Reinforcement Fibers on the Hygrothermal Properties of Earthen Plasters in Mogao Grottoes of China

Murals in Mogao Grottoes consist of three parts:support layer,earthen plasters and paint layer.The earthen plasters play a key role in the preservation of murals.It is a mixture of Dengban soil,sand,and plant fiber.Two different natural fibers,hemp fiber and cotton fiber,were reinforced to earthen plasters in the same percentage to evaluate the influence on hygrothermal performance.The two types of earthen plasters were studied:one containing hemp fiber in the fine plaster(HFP)and the other containing cotton fiber in the fine plaster(CFP).Specific heat capacity,dry thermal conductivity,water vapor permeability,and sorption isotherms were investigated.The results showed that the difference between two natural fibers has much more impact on the hygric properties(water vapor permeability and sorption isotherms)of earthen plasters than on their thermal performance(specific heat capacity and dry thermal conductivity).The CFP with higher density has higher thermal conductivity than the HFP with lower density.But no significant differences of specific heat capacity were observed.Compared with HFP,CFP used in murals can reduce the rate of water transfer and prevent salt from transferring water to the mural surface.The overall findings highlight that all these features of CFP are beneficial to the long-term preservation of murals.The study of the earthen plasters in Mogao Grottoes is of general significance,and the measured properties can be used to obtain coupled heat and moisture analysis of the earthen plasters and to dissect the degradation mechanism of murals.

Exploring building's envelope thermal behavior of the neo-vernacular residential architecture in a hot and dry climate region of Algeria

It is well known that the passive strategies applying in traditional buildings respond satisfactory to climatic requirements and succeed to provide maximum indoor comfort with minimum energy consumption.From this point of view,it is interesting to quantitatively assess the effectiveness of the vernacular strategies to improve the environmental performance of the building's envelope under desert climate conditions.The research tries to address this issue and was undertaken in southern Algeria where a very hot and arid climate prevails.The effect of some selected passive cooling strategies on enhancing the building's envelope climate performance was examined.These strategies are inspired from the local vernacular architecture,and they are expected to provide satisfactory indoor thermal comfort for users and to reduce the energy cooling demand from residential buildings.Applying field and computational investigations,two existing residential buildings were tested:a typical residential unit and a contemporary vernacular(neo-vernacular)building.In the latter,climate responsive strategies inspired from vernacular architecture were applied.A comparison based on site measurements was carried out on the two selected buildings which differ from their envelope design properties and components.

Possible solutions for sludge dewatering in China

In China,over 1.43×10^(7)tons of dewatered sewage sludge,with 80%water content,were generated from wastewater treatment plants in 2007.About 60%of the COD removed during the wastewater treatment process becomes concentrated as sludge.Traditional disposal methods used by municipal solid waste treatment facilities,such as landfills,composting,or incineration,are unsuitable for sludge disposal because of its high water content.Disposal of sludge has therefore become a major focus of current environmental protection policies.The present status of sludge treatment and disposal methodology is introduced in this paper.Decreasing the energy consumption of sludge dewatering from 80%to 50%has been a key issue for safe and economic sludge disposal.In an analysis of sludge water distribution,thermal drying and hydrothermal conditioning processes are compared.Although thermal drying could result in an almost dry sludge,the energy consumption needed for this process is extremely high.In comparison,hydrothermal technology could achieve dewatered sewage sludge with a 50%–60%water content,which is suitable for composting,incineration,or landfill.The energy consumption of hydrothermal technology is lower than that required for thermal drying.

Effects of Different Types of Sludge on Soil Microbial Properties:A Field Experiment on Degraded Mediterranean Soils

The recycling of suitable organic wastes can enhance soil fertility via effects on soil physical, chemical and biological properties. To compare the effects of digested (DS), thermally dried (TDS) and composted dewatered (CDS) sewage sludge on soil microbiological properties, an experiment was conducted at field sites for more than one year (401 d) when applied to two Mediterranean degraded soils (loam and loamy sand soils). All three types of sewage sludge had a significant effect on measured parameters. In a short time, the plots of both loamy sand and loam soils amended with TDS showed the highest microbial basal respiration (loam soil: P < 0.01; loamy sand soil: P < 0.001) and carbon mineralization coefficient (loam soil: P < 0.01; loamy sand soil: P < 0.001). Furthermore, on loamy sand soil, the plots amended with TDS showed the highest microbial metabolic quotient (qCO 2 ) (P < 0.05). This study revealed that the addition of sludge caused transient non-equilibrium effects on almost all soil microbial properties. However, there were no differences one year later because the remaining organic carbon was stable and quite similar in all treatments. These results may have practical implications for the rehabilitation of degraded soils.