V. Eroglu

Identification of Archaeal population in the granular sludge of an UASB reactor treating sewage at low temperatures

Effect of low temperature on up-flow anaerobic sludge bed (UASB) reactor performance treating raw sewage was investigated in terms of the variations in methanogenic diversity using the 16S rRNA based Fluorescence In-Situ Hybridization (FISH) technique. The diversity of microorganisms present in the anaerobic granular sludge and the structure of the granules operated at 13°C have been investigated using FISH combined with CSLM (Confocal Scanning Laser Microscopy). According to FISH results, archaeal cells representing methanogens were found intensively dominant in the bottom sampling port of the UASB reactor and acetoclastic Methanosaeta was the abundant methanogen. Other methanogens such as Methanosarcina and Methanobacterium like species were also observed. The abundance of originally mesophilic Methanosaeta-related Archaea under low temperature at all sampling days revealed the microbial adaptation to psychrophilic conditions. This might be attributed to the enzymatic alterations in Methanosaeta cells originating from seed sludge, which were exposed to sub-mesophilic temperatures at start-up and then to psychrophilic conditions during gradual decreases of temperature. According to CSLM observation, even though the sludge retained in the reactor kept its granular form as a whole, the majority of the granules had a tendency to be partly broken and they lost their rigidity when raw sewage was fed following synthetic sewage. Besides, Methanosaeta related species prevailing in seed sludge have noticeably lost their long filamentous forms and deteriorated during raw sewage feeding. Members of the order Methanobacteriales constituted the major hydrogenothrophic methanogens present in the psychrophilic UASB reactor, whereas the other hydrogenothrophic methanogens—members of the order Methanococcales and Methanogenium relatives—were absent.

Pretreatment requirements and status of industrial effluents in the greater Istanbul area

Evaluation of the industrial pretreatment plants in Istanbul Metropolitan area is presented. Out of 7899 industries located in Istanbul, 1420 of them require pretreatment to meet the discharge criteria. Currently, there are 532 pretreatment works which treat 82.6 percent of the industrial wastewaters. Discharge standards and the compliance monitoring system for the industrial wastewater discharges into the public sewers as applied by the Istanbul Water and Sewerage Administration are discussed. The performance data of the pretreatment plants are given based on the percent non-compliance and percent removal efficiency figures determined for different categories of industry. Problem areas in terms of industrial sector and in terms of quality parameters are identified.

DETACHMENT MECHANISMS OF DEPOSITED MATERIAL IN A BACKWASHED FILTER

Theoretical and experimental studies were performed to evaluate the detachment mechanisms of deposited material by fluidizing the filter media. The hydrodynamic characteristics of a backwashed filter and the energy dissipation during backwashing processes were investigated. The existence of a viscous sublayer around each fluidized particle and laminar sublayer thickness at the wall were neglected. Direct measurements of the effluent turbidity Te and the total backwash water volume V bt were made during backwashing in the laboratory experiments. Some relationships applicable to backwashing processes were developed with good accuracy. The turbulence parameter Ca 0.5/Re which characterizes the effect of turbulence fluctuations in a backwashed filter increased with increasing fraction solids (1−ε) and decreased with increasing the Reynolds number of the flow Re. The detachment rate of deposited material rd was found to vary with hydrodynamic shear (ι a ), turbulence fluctuations (Ca 0.5/Re) and backwash water volume (Vb ). Maximum shear stress caused a maximum detachment of the deposited material from the filter media. The detachment rate of deposited material rd had a minimum value at the turbulent parameter of 0.9 and fraction solids of 0.3. Also the detachment rate of the deposited material rd decreased with increasing the unit backwash water volume Vb which is the ratio of the total backwash water volume V bt to the expanded bed volume Ve .

Marine outfall alternative to solve the color problems of pulp and paper industry effluents

In this paper, elimination of color from the effluents of the secondary stage biological treatment plant of an integrated pulp and paper mill located at a tourism resort was investigated by using a marine outfall system. The investigated mill has a full-scale aerated lagoon system treating effluents from a chemical pre-treatment plant. The colored effluents from the treatment plant have been discharged to a river ending in the Mediterranean and this has resulted in deterioration of the natural appearance of the coastal waters used for recreational purposes. In this study, a marine outfall system with a diameter of 1200 mm and a multiport diffuser of 290 m were planned to eliminate the color problem from the lagoon effluents. The required initial dilution to reduce the color to unnoticeable levels in the marine environment was determined 70 by laboratory-scale dilution experiments. In addition to these investigations, long-term full scale treatment results of the related industry are presented. Oceanographic studies and water quality measurements were performed to evaluate the effects of effluents from the industry on the marine environment. Bioassay tests were also conducted to assess the toxic impacts of the secondary treatment effluents on the macro fauna using Lapistes retucularis as a test species. Considering these findings, a marine outfall system was designed. The designed marine outfall system is currently under construction.

Cost Effective Treatment of Textile Mill Effluents by Water Reuse

The treatment results of a full scale plant treating the effluents from an integrated woolen textile industry have been presented. Effluents from the wool finishing process were recirculated after chemical treatment followed by rapid sand filtration. This practice provides a reduction of about one million US Dollars per year in the treatment cost, which corresponds to a pay back period of one year for the whole investment. Lanolin, which is recovered from the acid-cracking sludges, is a valuable by-product resulting in an extra reduction in the treatment cost.