International Journal of Environmental Engineering (5 papers in press)
Comparison of performance of three different seeding sludge under three different hyper-thermophilic temperatures
by Isaac Mbir Bryant, Marko Burkhardt, Marion Martienssen
Abstract: The performance of three seeding sludge under three different hyper-thermophilic temperatures, 60 oC, 65 oC and 70 oC was investigated and compared with optimal mesophilic (37 oC) and thermophilic (55 oC) temperatures using the same seeding sludge and substrate in batch tests. Three different seeding sludge: Sludge from Cottbus Wastewater Treatment Plant (LWG), Sludge from thermophilic reactor in Brandenburg University of Technology, Germany (BTU) and Cow Manure (CM) were selected. The performance of the three sludge was compared based on net normalized cumulative volume of methane content, methane yield and higher degree of COD degradation of the black water. Cow manure at 65 oC recorded the highest net normalized cumulative volume of methane content (387.2 mlNCH4-%), methane yield (231.7 mlNCH4/gVS) and degree of COD degradation (79.1%) while BTU at 70 oC recorded the least performance of methane yield (0.0 mlNCH4/gVS) and content (0.0 mlNCH4-%) and degree of COD degradation (0.0%).
Keywords: Methane yield; Net cumulative methane content; Degree of COD degradation; Hyper-thermophilic temperatures; Seeding sludge; Biogas.
Evapotranspiration for cotton in plain and hilly areas in Chuadanga and Rangamati districts in Bangladesh using Penman method
by Mahbub Hasan, Aschalew Kassu
Abstract: Water management and its appropriate application for cultivating cotton have been a promising issue to ensure the best quality and quantity of production. Rainfall intensity and pattern, differences in temperature, and cloudiness and non-cloudiness during the growing season, will affect crop water requirement. Different studies showed that excess or less water uses result into a lower yield. Evapotranspiration of any crop is predominantly dependent on environmental factors and crop factors. The environmental factors are further critical for energy requirement for crop development where sunshine hours, intensity of sunshine, duration of sunshine, temperature, and relative humidity play the vital role. Due to the change in geographical location, the energy availability for contributing in the evapotranspiration is also different. Hence, the water requirement for the same cotton crop may vary for two different locations. A dependable and reliable scheduling system for irrigating is desirable for timeliness and quantity of water to irrigate for potential yield of cotton. In this article, a reliable approach to determine crop water requirement for cotton cultivation is proposed using the Penman method for Chuadanga, representing the flat land, and Rangamati, representing hilly areas of Bangladesh.
Keywords: evapotranspiration (ETc); Penman method; reference crop coefficient (Kc); Cotton irrigation; hilly and non-hilly areas ET; net radiation (Rn); energy balance.
CHARACTERIZATION OF NANO-SIZED PARTICLES IN CHEMICAL MECHANICAL POLISHING WASTEWATER
by NOOR AINA MOHAMAD ZUKI, NORLI ISMAIL, FATEHAH MOHD OMAR
Abstract: Treatment of chemical mechanical polishing (CMP) wastewater and fluoride-containing wastewater in semiconductor manufacturing are conventionally separated. The combined treatment of these two streams of wastewater was studied in terms of zeta potential and z-average hydrodynamic diameter profiles as a function of pH 2 to 12. Optimum pH for CMP wastewater was at pH 6 with zeta potential value of -10 mV and mean particle size of 180 d.nm. Meanwhile, for fluoride-containing wastewater the optimum pH obtained was at pH 9 with zeta potential of 10 mV and mean particle size of 5214 d.nm. These two streams were combined together at their respective optimum pH and resulted a zeta potential value of 0.55 mV and mean particle size of 12590 d.nm. Results indicated that the combined treatment for both polishing and fluoride-containing wastewater were beneficial as a larger flocs of fluorosilicate (SiF62-) was generated without the presence of coagulation chemicals. It is proposed that positively charged particles present in fluoride-containing wastewater become adsorbed on the surface of silica nanoparticles in CMP wastewater in which act as nuclei and enhances flocculation since repulsive force of both wastewater is decreased.
Keywords: Semiconductor wastewater; chemical mechanical polishing; pH; zeta potential; particle size; aggregation; disaggregation.
The Influencing Factors Study on Environmental Responsibility Motive of Oil and Gas Enterprises
by Yanling Xiao, Yanmei Sheng, Yuanyuan Liu
Abstract: Nowadays, with the rapid development of the economy and the intensification of global environmental pollution, people's quality of life has not improved, so the voice of green development is growing. In China, as heavily polluting enterprises, oil and gas enterprises, while playing a major role in national economy and the people's livelihood, should assume the environmental responsibility of state-owned enterprises. Through in-depth corporate research and survey questionnaires, the influencing factors of the environmental responsibility motive of oil and gas enterprises are explored. Principal component analysis method was used to reduce dimensionality of influencing factors, extract four main influencing factors, namely comprehensive supervision, enterprise development capability, ecological sustainable development, and construction of laws and regulations. Then the relationship between each influencing factor and the implementation of environmental responsibility of oil and gas enterprises, so as to the relationship between various factors, was analyzed in depth, and the causality diagram was creatively drawn according to the system dynamics principle. On this basis, the realization path of the environmental responsibility dynamic mechanism of oil and gas enterprises is proposed, which is of great significance for promoting the fulfilment of the environmental responsibility of oil and gas enterprises and achieving ecological sustainable development.
Keywords: oil and gas enterprise; environmental responsibility; influencing factors; dynamic mechanism.
Analysis of Vegetation Community Landscape Structure Based on Eco-tourism Management
by Chunjiang Yang, Yujiang Yang, Xiuli Tan
Abstract: Vegetation community is an important factor to enrich green landscapes and an important index to evaluate their greening level. With the development of economy and the acceleration of urbanization, single vegetation landscapes have failed to meet people's aesthetic vision. For ecotourism management, this study takes the two cities of Anshan, Liaoning and Yantai, Shandong as an example to analyze the forest vegetation community in Anshan and the road vegetation community of Yantai. The results showed that herb coverage, shrub coverage, shrub frequency, proportion of arbors and needles, number of shrubs and average diameter had a certain influence on forest community landscape. The relationship between the number of arbors and shrubs and the diameter of arbors had significant influence on forest landscape. Besides, a structural design was carried out on road landscape based on color and space in order to meet the cooling, noise reduction and shadowing functions to highlight the uniqueness of urban road landscape, combining with the speed of the pacers and drivers. Through the structural analysis of the two plant community landscapes, the related support for the structural design of the future plant community landscapes is provided.
Keywords: ecotourism; vegetation community; landscape structure.