Comparative Assessment of Sludge Pre‐Treatment Techniques to Enhance Sludge Dewaterability and Biogas Production

Effectiveness of ultrasonication, microwave technologies, and enzyme addition prior to anaerobic digestion is investigated using sludge samples taken from the secondary settling tank of a domestic wastewater treatment plant to improve methane production, enhance dewaterability characteristics of the sludge, and to reduce excess sludge. Microwave pre‐treatment (1500 W, 10 min at 175 °C) results in better extra digester performance (compared to the control reactor) in terms of methane production (25 m³ ton^?1 suspended solids (SS)) than ultrasound (no improvement) and enzyme pre‐treatment (11 m³ ton^?1 SS). While methane production is not improved as a result of ultrasonication pre‐treatment (15 000 kJ kg^?1 SS), a noticeable increase (19%) is observed in the case of microwave pre‐treatment. Higher compactibility values are obtained after ultrasonication and microwave application compared to the control (i.e., from 7.1 to 8.7 and 9.2%, respectively) before anaerobic digestion. Although ultrasonication and microwave application decrease the dewaterability of the raw sludge (capillary suction time (CST) from 827 to 1364 and 2290 s, respectively), similar dewaterability results are obtained at the end of the anaerobic digestion process for all pre‐treated sludge samples. An economic assessment of this study shows that pre‐treatment with microwave results in more than 10‐fold less net cost compared to the enzyme application.     

Soil and water pollution derived from anthropogenic activities in the Porsuk River Basin, Turkey

This study aims to investigate the degree of the influence of contaminant sources on both the surface (Porsuk River) and groundwater in the Eskisehir plain, (Turkey) and to determine the changes in groundwater quality after the sewage system was started in 1998. For this purpose surface and groundwater samples were collected from various locations in the Eskisehir plain between May and October, 2001. The Porsuk River is already polluted in the upstream wastewater and by industries such as Nitrogen Fertilizer Factory, Sugar-beet Factory, and Magnesite Factory located around the city of Kutahya. This high-contaminated water forms an eutrophic environment which generates high phosphorus and nitrogen in downstream flow. Agricultural and industrial activities in the Eskisehir plain are an additional source of the pollution of the Porsuk River. The study revealed that some trace elements, Pb, Cr, Mn, Fe, and Cd, are present in high concentrations both in the surface and groundwater besides extremely high quantities of phosphorus, nitrogen and sulfide compounds. In addition, analyses of samples also indicated that there are no considerable contaminations in terms of local pesticides. High concentration of Cd, N and S are found in the groundwater. On the basis of a detailed analysis of the groundwater in the Eskisehir plain, it is concluded that groundwater is not suitable for drinking according to Turkish standards, European Union Standards (EU) and World Health Organization (WHO). An erratum to this article can be found at     

Seismic performance evaluation of traditional timber <Emphasis Type="Italic">Hımış</Emphasis> frames: capacity spectrum method based assessment

Timber constructions have been widely suggested to be seismically resistant based on post-disaster reconnaissance studies. This observation has, however, remained to a large extent anecdotal due to the lack of experimental work supporting it, especially for certain timber architectural forms, including traditional timber frame “h?m??” structures. To fill this gap, the authors carried out an extensive full-scale testing scheme using frames of various geometrical configurations, tested under reverse-cyclic lateral loading with/without infill (brick and adobe) or cladding (ba?dadi and ?amdolma) (Aktas et al. in Earthq Spectra 30(4):1711–1732, 2014a, b). The tests concluded that h?m?? frames had high energy dissipation capabilities due mostly to nailed connections. Infill/cladding significantly helped improve stiffness and lateral load strength of the frames, and timber type did not seem to make a remarkable impact on the overall behaviour. The current paper, on the other hand, uses test data to calculate capacity/demand ratios based on capacity spectrum method and Eurocode 8 to elaborate more on the performance of “h?m??” structures under seismic loading. The obtained results are discussed to draw important conclusions with regards to how frame geometry and infill/cladding techniques affect the overall performance.     

Estimation of soil temperatures with machine learning algorithms—Giresun and Bayburt stations in Turkey

Theoretical and Applied Climatology - Since soil temperature (ST) is one of the most critical determinants affecting the soil’s physical and chemical properties, the studies on soil...     

土耳其Pütürge变质地体晚白垩世岩浆作用与变质作用的年代学研究

Pütürge变质地体位于新特提斯构造带南部的土耳其Anatolia逆冲推覆构造带内,形成于欧亚板决与阿拉伯板块之间晚白垩纪碰撞造山事件.Pütürge变质地体主要由变质泥质片岩及片麻岩、花岗质片麻岩、石英岩、角闪岩和大理岩组成,发育类似巴罗型递增变质带的变质带序列,变质程度达高绿片岩相至低角闪岩相.此前该变质地体一直缺乏精确的年代学约束,为此我们采用了二次离子质谱锆石U-Pb测年方法和黑云母40Ar/39 Ar测年方法,对该变质地体进行了年代学研究.结果表明,区内花岗片麻岩原岩形成于84.2±1.1Ma,变质泥质片麻岩中黑云母40Ar/39 Ar年龄所代表的变质时代为83.21±0.1Ma.这说明早白垩世期间岩浆侵入事件不久,Pütürge变质地体就发生了区域变质作用.     

Effects of Different Carbon Sources on Denitrification Efficiency Associated with Culture Adaptation and C/N Ratio

Stringent effluent limitations for nitrogen necessitate an accurate interpretation of the design and operation conditions of biological nitrogen removal systems. In this study, the effects of the nature of the organic substrate on biomass adaptation and response to different C/N ratios in terms of denitrification efficiency were investigated. A relatively high chemical oxygen demand (COD)_utilized/NO_x–N_reduced ratio of 8.1 was obtained when an excess amount of readily biodegradable carbon was supplied, which is suggested as the conversion of substrate surplus into storage polymers. An anoxic yield of 0.64 g cell COD/g COD for a four‐compound substrate mixture (acetate, propionate, ethanol and glucose), 0.63 g cell COD/g COD for a two‐compound substrate mixture (acetate and propionate), and 0.5 g cell COD/g COD for methanol were calculated. Fluorescence in situ hybridization analysis showed that the β‐subclass of proteobacteria was dominant in the seed and in cultures adapted to both the four‐compound and the two‐compound substrate mixture, whereas in the methanol‐adapted culture significant amounts of β‐proteobacteria were detected. The biocommunity composition, the type of organic compound and the COD/NO₃–N ratio strongly influence the nitrate reduction and carbon utilization profiles. Methanol has been shown to select for a denitrifying population consisting of Paracoccus and Hyphomicrobium vulgare genera, when used as only external carbon source.     

Monitoring of earthquake precursors by multi-parameter stations in Eskisehir region (Turkey)

The objective of this study was to investigate the geochemical and hydrogeological effects of earthquakes on fluids in aquifers, particularly in a seismically active area such as Eskisehir (Turkey) where the Thrace–Eskisehir Fault Zone stretches over the region. The study area is also close to the North Anatolian Fault Zone generating devastating earthquakes such as the ones experienced in 1999, reactivating the Thrace–Eskisehir Fault. In the studied area, Rn and CO₂ gas concentrations, redox potential, electrical conductivity, pH, water level, water temperature, and the climatic parameters were continuously measured in five stations for about a year. Based on the gathered data from the stations, some ambiguous anomalies in geochemical parameters and Rn concentration of groundwater were observed as precursors several days prior to an earthquake. According to the mid-term observations of this study, well-water level changes were found to be a good indicator for seismic estimations in the area, as it comprises naturally filtered anomalies reflecting only the changes due to earthquakes. Also, the results obtained from this study suggest that both the changes in well-water level and gas–water chemistry need to be interpretated together for more accurate estimations. Valid for the studied area, it can be said that shallow earthquakes with epicentral distances of <30 km from the observation stations have more influence on hydrochemical parameters of groundwater and well-water level changes. Although some hydrochemical anomalies were observed in the area, it requires further observations in order to be able to identify them as precursors.