Wet oxidation: a pre-treatment procedure for sludge

Wet oxidation process is specially effective for wastes with a high organic matter which can not be removed by conventional treatment methods. The digested and raw activated sludges of PAKMAYA yeast factory are treated by wet oxidation process. The liquid-phase organic matter concentration [as total organic carbon (TOC)] was increased by 16.5% in 10 min during the wet oxidation in the presence of Cu as catalyst and H2O2. Lenghtening the period of the wet oxidation, the TOC-concentration was increased by 66% in 120 min. The biodegradability of the sludge after wet oxidation process was also examined. A very little development in the biodegradability was observed, when wet oxidation was applied as pre-treatment to the digested sludge (5% decrease as TOC, in the presence of Cu catalyst and H2O2). However, in the case of digestion of the raw sludge after the application of wet oxidation, the biodegradability increased significantly (approximately 75%, as TOC). Moreover, wet oxidation improved the ability of settling of sludge solids, as well as enhancing the treatment efficiency. Finally, the volume of settled solids was decreased by 80% in the presence of Cu and H2O2. NH3+-N, NO2(-)-N and NO3(-)-N concentrations in the supernatant decreased with the wet oxidation. pH value of the sludge increased from 6.6 to 7.8-8.0. Since stable sludge was taken from the digester where the nitrification process was progressing, a decrease in the nitrite concentration, with an increase in nitrate was observed in the digestion continuing after the wet oxidation pre-treatment. However, in the raw activated sludge, there was a nitrite formation only in the non-pretreated sludge.     

A mathematical model for the anaerobic treatment of Baker's yeast effluents

Baker's yeast fermentation produces high strength wastewaters containing high concentrations of organic materials that cannot easily be degraded by biological processes. A two-stage (anaerobic-aerobic) treatment system has been used in order to treat this effluent efficiently. Most of the COD reduction takes place during the anaerobic degradation. The objective of this study was to generate a simple mathematical model for the anaerobic stage. The model, which is based on the elimination of COD, assumes that only three consecutive reactions namely hydrolysis, acidogenesis and methanogenesis are significant. In the laboratory-scale experiments, feed strength was increased from 3600 to 14,000 mg O2 l-1 in a batch reactor. Three reaction rate constants were found as 0.08, 0.004, 0.06 h-1 by analyzing data from the laboratory experiments. The model was tested and found to be congruent with the daily operation data, which were collected from the Pakmaya Baker's Yeast Kocaeli Factory Plant. This plant contains three Upflow Anaerobic Sludge Blanket reactors, which are run in series. The rate constants of the hydrolysis and methanogenesis were similar to the batch experiment case.     

Spatial Considerations in Wet and Dry Periods for Phosphorus in Streams of the Fort Cobb Watershed,United States

The Fort Cobb Watershed in Oklahoma has diverse biogeophysical settings and provides an opportunity to explore the association of water quality with a diverse set of landscapes during both wet (April 2007‐December 2009) and dry (January 2005‐March 2007) periods. The objective of this work was to identify spatial patterns in phosphorus (P) (soluble reactive P [SRP] and bioavailable P [BAP]) associated with landscape metrics for two distinct streamflow regimes. Spatial autocorrelation of P was evaluated using contiguous (side‐by‐side) and upstream (upstream:downstream) connectivity matrices. Biogeophysical metrics were compiled for each contributing area, and were partitioned based on association to P concentrations. Results for both SRP and BAP indicated that spatial autocorrelation was present (p < 0.05). There was more spatial autocorrelation and stream P concentrations were three to five times higher in the Wet phase than in the Dry phase (p < 0.05). Analysis with recursive partitioning resulted in higher R² with spatial autocorrelation than without spatial autocorrelation and indicated that lateral metrics (topography, soil, geology, management) were better predictors for SRP than instream metrics. During Wet phase, lateral metrics indicative of rapid surface and subsurface water movement were associated with higher P stream concentrations. This research demonstrated that we can detect landscapes more vulnerable to P losses and/or contaminations in either drought or very wet periods.     

An experimental study of an LPG tank at low filling level heated by a remote wall fire

This paper describes an experimental study of 2300 L pressure vessels exposed to remote fire heating by a natural gas fuelled wall fire simulator. The tanks were filled to 15% capacity with commercial liquid propane. The flame intensity and distance were varied to study the effect of different heating levels on the tank and its lading.The fire simulator is first characterized with tests including fire thermocouples, radiative flux meters and thermal imaging. With the appropriate positioning of a target tank it is possible to get very realistic fire heat fluxes at the tank surface.Three tests were conducted with the 2300 L tanks filled to 15% capacity with propane. The tanks were positioned at three different distances from the wall fire resulting in measured average peak heat flux at the tank surfaces ranging between 24 and 43 kW m^?2. The data shows rapid rise in vapour space wall temperatures, significant temperature stratification in the vapour space, and moderate rate of pressure rise. These results provide excellent data for the validation of computer models used to predict the response of pressure vessels exposed to moderate heating from a remote fire.     

World mineral production and consumption in 1978

This article is an abridged version of a report on the status of world mineral production and consumption in 1978. Various indexes are used to assess the position in 1978 in comparison with that of earlier periods (1950 and 1973). The data given in this article are based on the calculation of mining production in terms of value. 51 major minerals are dealt with — six fuel materials, 22 metal materials, and 23 non-metal materials.     

Formation of radioactivity enriched soils in mountain areas

A field study was carried out in the Mercantour Mountains at 2200 m altitude to investigate the processes of soil enrichment in atmospheric Chernobyl (137)Cs. Soils with high (137)Cs activities have been collected in the pasture areas with frequently measured (137)Cs activity values of the order of 7000 Bq m(-2). At some single spots (about 6% of the studied area), activity in soils reached 300000 Bq m(-2), which represents 44% of the (137)Cs of the total area. Data further showed that spatial distribution of Cs depends widely on its origin: Chernobyl Cs is mainly concentrated in "enriched" soils, whereas older Cs and (241)Am fallout from nuclear weapons tests (NWTs) and natural atmospheric (210)Pb in soils is less heterogeneously distributed.In order to elucidate the processes which have led to the enrichment in Chernobyl (137)Cs in the Alps in May of 1986, we have studied the repartition of atmospheric (7)Be isotope (half-life=53.3 d) in the pasture compartments (soil, litter, grass, and snow). Snow (7)Be data give evidence that fallout enrichment is related to snow accumulation (snow drift). The transfer of beryllium occurs rapidly to the grass and litter, where the strongest pollutant accumulations were measured. However, (7)Be transport to the soil required more than 8 months.     

Towards a clean Izmit Bay

The elongated semi-enclosed Bay of Izmit, which receives both domestic and industrial wastes, has been monitored by measuring its physical and biochemical parameters for 2 years, 1994-1995. It is clear that there are two distinct water masses. The upper layer has been occupied by the less saline (22-26 ppt) waters of the Black Sea origin; whereas the lower layer contains saline (38.5 ppt) Mediterranean waters. The seasonal variations in the biochemical characteristics were dependent on the bay's two-layer flow system. If one considers the distribution of transparency in the upper bay waters, it has been observed that the Secchi disk depth (SDD) decreases from west to east. Furthermore, these depths are limited by the high primary productivity associated with the low concentrations of nutrients observed during the spring. Discharges of wastes into the surface waters significantly affect the biological production and oxygen consumption in the lower layer. Within the last 10 years, 80% of organic matter has been removed from industrial wastewater. However, organic loads from the domestic wastewaters have doubled because of the growth in the surrounding population. Fortunately, as a result, the total organic loads in the bay have not changed significantly within the last 10 years.     

The Effect of UV-B Irradiation on the Biodegradability of Poly-β-Hydroxybutyrate (PHB) and Poly-ɛ-Caprolactone (PCL)

The biodegradability of poly--hydroxybutyrate and poly--caprolactone in soil compostage before and after irradiation of the polymers for 192, 425, and 600 h in a Weather-Ometer was examined. The biodegradability tests were done in soil compostage at pH 7.0, 9.0, and 11.0 to assess the influence of this parameter on degradation. The rate of degradation was directly proportional to the soil alkalinity. Poly--hydroxybutyrate showed the greatest weight loss and aging in a Weather-Ometer did not significantly increase the biodegradation, except when the polymer was aged for 425 h and buried in soil compostage of pH 11.0.     

利用寿命周期评估(LCA)进行的鲑科鱼饲料的环境影响评价

了解与水产饲料有关的环境负荷是评价和改进水产养殖环境性能的一项重要内容.本研究的目的是利用寿命周期评估(LCA)评价与法国用于硬头鳟生产的饲料有关的环境影响.所评价的各个阶段为:原材料的提取,所使用的原始配料的生产与改造,饲料的生产,饲料在养殖场的使用,各个阶段的运输以及能源的生产和使用.评价结果显示,渔业资源的利用(例如生物资源利用)以及养殖场中营养物的排放(例如富营养化潜能)对鲑科鱼饲料的潜在环境影响所起作用最大.改进饲料的组成以及管理做法看来是改善水产饲料环境概貌的最佳途径.