Morphological features of thermophilic activated sludge treating food industry wastewater in MBR

Microscopic examination of the activated sludge and morphological characterization of the flocs provides detailed information about the treatment process. The aim of this study is to investigate the morphological parameters of flocs obtained from a thermophilic jet loop membrane bioreactor (JLMBR) in different sludge retention times (SRTs), considering EPS and SMP concentration, hydrophobicity, zeta potential. The results showed that irregularity decreased with the increasing SRT. The compactness value was calculated to be less than 1 for all SRTs. However, the sludge had a more compact structure when the SRT increased. Zeta potential increased whereas hydrophobicity and floc size reduced, with increasing SRT. Furthermore, 2-D porosity calculated using the hole ratio was higher at greater SRTs. Hence, there was a significant correlation between the results obtained using the imaging technique and operation conditions of thermophilic JLMBR. © 2018 Techno-Press, Ltd.110Y134This study was financially supported by the Scientific and Technological Research Council of Turkey (TUBITAK) with the project number 110Y134

Membrane fouling in thermophilic aerobic membrane distillation bioreactor treating hospital wastewater

In the membrane distillation bioreactor (MDBR) process, flux increases with increasing feed temperature, but the presence of microorganisms limits the feed temperature. Also, the accumulation of cells and other substances on the membrane surface can affect the efficiency of MDBR. In this study, hospital wastewater was treated by thermophilic activated sludge MDBR. In the MDBR, the initial flux was 7.87 L‧m−2·h−1 and the stable flux was 3.88 L‧m−2·h−1. The particle size, zeta potential and hydrophobicity of the activated sludge in MDBR were 2.25 µm, −14 mV and 24%, respectively. In addition, EPS (extracellular polymeric substances) and SMP (soluble microbial products), having a significant effect on membrane fouling, were determined to be 201.50 mg·L−1 and 669.35 mg·L−1 in MDBR, respectively. Contact angle, FTIR (Fourier transform infrared), SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy) measurements were also made on a virgin membrane and used membrane. Analysis of EDX, SEM and F-TIR showed that the membrane fouling was caused by CaCO3 and EPS

Atmospheric heavy metal deposition in Duzce province by using mosses as biomonitors

WOS: 000244937300007This research was carried out around the industrialised area and D100 highway in Duzce, in order to determine the atmospheric heavy metal deposition by using mosses as biomonitors. Sampling was performed based on the principle that carpet-forming bryophytes (pleurocarpous mosses) at 14 sites distributed over the study area between 2003 and 2004. Dried samples were digested according to the wet digestion method, and the concentrations of heavy metals were determined by graphite-furnace atomic absorption spectrometry (AAS). According to the results of analyses, the heavy metal concentrations in the region are ordered as follows: Fe>Pb>Cu>Co>Cr>Ni>As. Distribution maps were drawn up by using the Geographic Information System (GIS) for each of the studied metals according to their concentration in the mosses. The results were compared with similar studies in Europe, and. it was observed that the accumulation ratios of iron, lead, arsenic and cobalt are higher than European rates. In addition, significant correlations were found among Fe-Cu and Co between the results, and control sites were compared by using SPSS statistical programme

Application of next-generation sequencing methods for microbial monitoring of anaerobic digestion of lignocellulosic biomass

The anaerobic digestion of lignocellulosic wastes is considered an efficient method for managing the world's energy shortages and resolving contemporary environmental problems. However, the recalcitrance of lignocellulosic biomass represents a barrier to maximizing biogas production. The purpose of this review is to examine the extent to which sequencing methods can be employed to monitor such biofuel conversion processes. From a microbial perspective, we present a detailed insight into anaerobic digesters that utilize lignocellulosic biomass and discuss some benefits and disadvantages associated with the microbial sequencing techniques that are typically applied. We further evaluate the extent to which a hybrid approach incorporating a variation of existing methods can be utilized to develop a more in-depth understanding of microbial communities. It is hoped that this deeper knowledge will enhance the reliability and extent of research findings with the end objective of improving the stability of anaerobic digesters that manage lignocellulosic biomass

Fungal bioaugmentation of anaerobic digesters fed with lignocellulosic biomass: What to expect from anaerobic fungus Orpinomyces sp.

Energy-efficient biogas reactors are often designed and operated mimicking natural microbial ecosystems such as the digestive tracts of ruminants. Anaerobic fungi play a crucial role in the degradation of lignocellulose-rich fiber thanks to their high cellulolytic activity. Fungal bioaugmentation is therefore at the heart of our understanding of enhancing anaerobic digestion (AD). The efficiency of bioaugmentation with anaerobic fungus Orpinomyces sp. was evaluated in lignocellulose-based AD configurations. Fungal bioaugmentation increased the methane yield by 15-33% during anaerobic co-digestion of cow manure and selected cereal crops/straws. Harvesting stage of the crops was a decisive parameter to influence methane production together with fungal bioaugmentation. A more efficient fermentation process in the bioaugmented digesters was distinguished by relatively-higher abundance of Synergistetes, which was mainly represented by the genus Anaerobaculum. On the contrary, the composition of the methanogenic archaea did not change, and the majority of methanogens was assigned to Methanosarcina

Evaluation of development in supercritical water oxidation technology

Supercritical water oxidation (SCWO) has been an innovative technology for the treatment of aqueous and hazardous organic wastes for 35 years. The technology provides cleaner output products and energy recovery. The purpose of this study is to evaluate the latest state of SCWO, which is an innovative and promising technology, according to the information obtained from the lab-scale, pilot-scale and full-scale applications. The process has been extensively used mostly in laboratory or pilot scale plants for model and real wastewater treatment. Industrial SCWO plants have usually closed due to corrosion, clogging and high cost problems. In order to operate this innovative technology efficiently, the main suitable wastewater should be selected, appropriate reactor design should be used, more durable materials should be produced, efficient pre-treatment should be determined so as to decrease operating costs and technical solutions should be determined. Otherwise, SCWO studies may be limited to laboratory and R&D studies

Supercritical water gasification of sewage sludge by continuous flow tubular reactor: A pilot scale study

Treatment and disposal of sewage sludge constitute one of the major problems of wastewater treatment plants due to high water content and more stringent environmental regulations. Supercritical water gasification (SCWG) technology is accepted as a promising method for sustainable sludge disposal because of the elimination of need for costly water reduction and drying processes before disposal by conventional methods. The aim of this study is to determine the effect of temperature (450–650 °C), solid matter content (1–2%) and catalyst addition (0.5–2% KOH) on supercritical gasification of sewage sludge in a continuous-flow pilot scale tubular reactor. The results indicate that the gasification efficiency is generally temperature dependent. Furthermore, catalyst addition improves the gasification efficiency at high solids content. The produced gas contains 60% of H2 and 22% of CH4 at experimentally determined optimal conditions (650 °C, 2% solid matter content, 2% KOH). The resulting gas contains H2S and CO below detection limits and there is no need for additional treatment. Consequently, SCWG technology provides complete decomposition of organic matter in a short time, clean gas formation with higher energy content, and volumetric reduction compared to conventional methods.Scientific Research Projects Coordinator-ship of Yildiz Technical University (BAP) Project Number: 2016-05-02-KAP01 and 2016-05-02-DOP0

Characteristics of liquid products in supercritical water gasification of municipal sewage sludge by continuous flow tubular reactor

Sewage sludge is a by-product of wastewater treatment, containing high water and organic content. Supercritical water gasification provides sustainable treatment for biomass sources such as sewage sludge. In this study, the effects of operating conditions (temperature, solid matter content and catalyst) and raw material properties on the resulting liquid products were determined in order to exhibit the success of this innovative technology for treatment and disposal of municipal sewage sludge using a continuous flow pilot-scale tubular reactor for the first time in Turkey. As a result of the study, it was determined that the higher the temperature, the higher the quality of the liquid product. TOC removal efficiencies increased from 84.4% to 99% with increasing the temperature from 450 to 650 °C, for 1% solid matter content. The pollutant concentrations in the liquid products increased by increasing the solid matter content of the raw sludge from 1 to 2%. This situation has been eliminated by the catalyst (KOH) addition, resulting in a very transparent liquid product. Additionally, TOC removal of 99.8% was obtained after addition of 2% catalyst. Thus, supercritical water gasification (SCWG) has been considered as a notable technology for the treatment and disposal of sewage sludge without the need of additional pre- or post-treatment

Biological pretreatment with Trametes versicolor to enhance methane production from lignocellulosic biomass: A metagenomic approach

The presence of poorly biodegradable components in lignocellulosic biomass limits the methane recovery in anaerobic digesters. The main reason to go for aerobic pretreatment before anaerobic digestion (AD) is to enable enzymatic cleavage of the aromatic rings in lignin by oxygen since it cannot be efficiently degraded under anaerobic conditions. In this study, the advantage of highly-cellulolytic white-rot fungi Trametes versicolor was taken by aerobic pretreatment prior to anaerobic co-digestion of cow manure and selected cereal crop materials (i.e. wheat, rye, barley, triticale) harvested at different stages. Fungal pretreatment improved the methane yield by 10%-18% and cellulose degradation up to 80%. Furthermore, higher volatile fatty acid (VFA) speciation was found in the anaerobic digesters upon fungal pretreatment. 16S rRNA gene amplicon sequencing revealed a more diverse microbial community in the fungal-pretreated anaerobic digesters. Generally, typically-detected bacterial species dominated the digesters; except that Synergistetes was only enriched in the fungal-pretreated digesters. Although Methanosarcianease was the predominant methanogenic archaea, a more diverse methanogenic population was identified in the fungal-pretreated digesters in which Methanobacteriaceaa and Methanomibrobiaceae also took role during biomethanation. Comparatively more unique microbiome of biogas reactors upon fungal pretreatment synergistically affected VFA production, cellulose degradation and eventually methane yield in an affirmative way. Considering the functional importance of bacterial and methanogenic archaeal populations, elevated knowledge of the microbial structures is essential for minimizing process failures and for creating strategies for process optimization of lignocellulose based-AD