ENVIS Energy and Environmental Systems RandD Ltd

İstanbul, Turkey

ENVIS Energy and Environmental Systems RandD Ltd

İstanbul, Turkey
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Sozen S.,ENVIS Energy and Environmental Systems R and D Ltd | Sozen S.,Technical University of Istanbul | Orhon D.,ENVIS Energy and Environmental Systems R and D Ltd | Orhon D.,The Science Academy | And 9 more authors.
Bulletin of Engineering Geology and the Environment | Year: 2017

This paper highlights resource recovery and stabilization as the novel approach adopted in the rehabilitation strategy of the abandoned copper mine site (CMC mine) located in Northern Cyprus, recognized as a source of chronic pollution problems. The site holds 9.5 million tons of tailings stored in poorly equipped ponds. The waste contains pyrite and chalcopyrite undergoing slow oxidation; this way, sulfide has been partly converted to sulfuric acid causing severe acid mine drainage problems. The rehabilitation strategy adopted the EU’s key principle of resource recovery, where all tailings would be processed for copper recovery and stabilized to further prevent the chemical mobility of heavy metals before final landfilling. A leaching-cementation process, with no chemical usage, except for lime stabilization after recovery, was designed for this purpose. The corresponding action plan entailed that all the waste material be processed in situ, in a zero waste environment. Accordingly, the remediation will be carried out in a sequential process involving emptying the ponds for resource recovery, preparing the necessary number of emptied ponds with sufficient holding capacity, as selected landfill sites in a way to secure and provide all necessary measures imposed by international regulations for containing and controlling hazardous wastes. Finally closure plans will be implemented for the rehabilitation of the mining site to reclaim full attributes of natural characteristics. © 2017 Springer-Verlag Berlin Heidelberg


Katipoglu-Yazan T.,Technical University of Istanbul | Katipoglu-Yazan T.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Merlin C.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Pons M.-N.,CNRS Reactions and Process Engineering Laboratory | And 3 more authors.
Water Research | Year: 2016

This study investigated the chronic impact of sulfamethoxazole (SMX) on activated sludge sustaining an enriched nitrifying biomass. For this purpose, a laboratory scale fill and draw reactor was operated with 100 mg COD/L of peptone mixture and 50 mg N/L of ammonia at a sludge age of 15 days. Additionally, the biomass was exposed to a daily SMX dose of 50 mg/L once the reactor reached steady-state conditions. The reactor performance and microbial composition were monitored for 37 days with conventional parameters and molecular techniques based on the gene for ammonia monooxygenase subunit A (amoA) and the prokaryotic 16S rRNA gene. Denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene cloning analyses suggested a microbial community change concurrent with the addition of SMX. Specifically, quantitative polymerase chain reaction analyses (qPCR/RT-qPCR) revealed a significant reduction in the levels and activity of ammonia oxidizing bacteria (AOB). However, the acclimation period ended with high amoA mRNA levels and improved nitrification efficiency. Partial degradation of SMX by heterotrophic bacteria was also observed. © 2016 Elsevier Ltd.


Ciggin A.S.,Akdeniz University | Orhon D.,Technical University of Istanbul | Orhon D.,ENVIS Energy and Environmental Systems R and D Ltd
Bioresource Technology | Year: 2014

The paper evaluated the impact of substrate storage on the respirometric assessment of process stoichiometry based on oxygen uptake rate (OUR) measurements. Two parallel sequencing batch reactors were operated with pulse feeding of synthetic substrate mixture at a sludge age of 8. days and 2. days. During the cycle experiments with acetate, 40-45% of acetate was converted to polyhydroxybutyrate, which was partly consumed during each cycle. Respirometric analysis also yielded OUR profiles for the corresponding cyclic operation. A mass balance expression was derived based on oxygen utilization. Oxygen demands calculated on the basis of partial PHB utilization closely matched the experimental values retrieved from OUR profiles within limits of analytical precision. The relative contribution of storage mechanism represented more than 50% of overall oxygen demand. Substrate storage, when totally disregarded or not properly evaluated, was observed to involve an error of around 10% on overall the oxygen demand. © 2014 Elsevier Ltd.


Sozen S.,Technical University of Istanbul | Pala-Ozkok I.,Technical University of Istanbul | Aysel M.,Technical University of Istanbul | Teksoy-Basaran S.,Technical University of Istanbul | And 6 more authors.
Desalination and Water Treatment | Year: 2014

The study investigated the effect of sludge age on substrate utilization kinetics, soluble microbial product generation, and composition of the microbial community sustained in a superfast submerged membrane bioreactor (SSMBR). For this purpose, a laboratory-scale membrane bioreactors (MBR) unit was operated at steady state, with three different sludge ages in extremely low range of 0.5-2.0 d, and a hydraulic retention time of 8.0 h. Substrate feeding was adjusted to 220-250 mg COD/L and involved a synthetic mixture representing the readily biodegradable COD fraction in domestic sewage. The MBR operation at sludge age of 1.0 d was duplicated with acetate feeding as the sole organic carbon source. Under different operating conditions, SSMBR was able to secure complete removal of available soluble/readily biodegradable substrate, with a residual microbial product level as low as 20-30 mg COD/L, partly retained and accumulated in reactor volume. Phylogenic analysis based on polymerase chain reactions-denaturing gradient gel electrophoresis analysis indicated that selected sludge ages affected the composition of microbial community. Lower sludge ages selected a community characterized by faster rates for microbial growth. Results confirmed the existence of a functional relationship between variable process kinetics and changes in the microbial community structure, even for slight variations that can be inflicted on the culture history while operating superfast MBR systems. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.


Katipoglu-Yazan T.,Technical University of Istanbul | Katipoglu-Yazan T.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Merlin C.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Pons M.-N.,CNRS Reactions and Process Engineering Laboratory | And 3 more authors.
Water Research | Year: 2015

This study evaluated the chronic impact of tetracycline on biomass with enriched nitrifying community sustained in a lab-scale activated sludge system. For this purpose, a fill and draw reactor fed with 100mg COD/L of peptone mixture and 50mgN/L of ammonia was sustained at a sludge age of 15 days. At steady-state, the reactor operation was continued with a daily tetracycline dosing of 50mg/L for more than 40 days, with periodic monitoring of the microbial composition, the nitrifying bacteria abundance, as well as the amoA and 16S rRNA gene activity, using molecular techniques. Changes in the kinetics of nitrification were quantified by modelling concentration profiles of major nitrogen fractions and oxygen uptake rate profiles derived from parallel batch experiments. Activated sludge modeling results indicated inhibitory impact of tetracycline on the growth of nitrifiers with a significant increase of the half saturation coefficients in corresponding rate equations. Tetracycline also inactivated biomass components of the enriched culture at a gradually increasing rate with time of exposure, leading to total collapse of nitrification. Molecular analyses revealed significant changes in the composition of the microbial community throughout the observation period. They also showed that continuous exposure to tetracycline inflicted significant reduction in amoA mRNA and 16S rRNA levels directly affecting nitrification. The chronic impact was much more pronounced on the ammonia oxidizing bacteria (AOB) community. These observations explained the basis of numerical changes identified in the growth kinetics of nitrifiers under stress conditions. © 2014 Elsevier Ltd.


Yagci N.,Technical University of Istanbul | Novak J.T.,Virginia Polytechnic Institute and State University | Randall C.W.,Virginia Polytechnic Institute and State University | Orhon D.,Technical University of Istanbul | Orhon D.,ENVIS Energy and Environmental Systems R and D Ltd
Bioresource Technology | Year: 2015

This study evaluates the biological solid reduction in a conventional activated sludge system with an anoxic/anaerobic side stream reactor receiving 1/10 of return sludge mass. Influent iron concentrations and feeding modes were changed to explore the consistency between the influent iron concentration and yield values and to assess the impact of feeding pattern. The results indicated that sludge reduction occurs during alternately exposure of sludge to aerobic and anoxic/anaerobic conditions in a range of 38-87%. The sludge reduction values reached a maximum level with the higher iron concentrations. Thus, it is concluded that this configuration is more applicable for plants receiving high iron concentrations in the wastewaters. © 2015 Published by Elsevier Ltd.

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