Search results for "environmental engineering"
showing 10 items of 2674 documents
Combination of the OSA process with thermal treatment at moderate temperature for excess sludge minimization
2019
Abstract This study investigated the chance to couple the conventional Oxic Settling Anaerobic (OSA) process with a thermic treatment at moderate temperature (35 °C). The maximum excess sludge reduction rate (80%) was achieved when the plant was operated under 3 h of hydraulic retention time (HRT). Compared with the conventional OSA system, the thermic treatment enabled a further improvement in excess sludge minimization of 35%. The observed yield coefficient decreased from 0.25 gTSS gCOD−1 to 0.10 gTSS gCOD−1 when the temperature in the anaerobic reactor was increased to 35 °C, despite the lower HRT (3 h vs 6 h). Moreover, the thermic treatment enabled the decrease of filamentous bacteria,…
Assessment and characterization of the bacterial community structure in advanced activated sludge systems
2019
Abstract The present study is aimed to assess and characterize the structure of bacterial community in advanced activated sludge systems. In particular, activated sludge samples were collected from an Integrated Fixed-film Activated Sludge – Membrane Bioreactor pilot plant under a University of Cape Town configuration with in-series anaerobic (Noair)/anoxic (Anox)/aerobic (Oxy) reactors – and further analyzed. The achieved results – based on Next Generation Sequencing (NGS) of 16S rDNA amplicons – revealed that the bacterial biofilm (bf) communities on plastic carriers of Oxy and Anox reactors had a greater diversity compared to suspended (sp) bacterial flocs of Oxy, Anox and Noair. Indeed,…
Solar and atmospheric forcing on mountain lakes
2016
We investigated the influence of long-term external forcing on aquatic communities in Alpine lakes. Fossil microcrustacean (Cladocera) and macrobenthos (Chironomidae) community variability in four Austrian high-altitude lakes, determined as ultra-sensitive to climate change, were compared against records of air temperature, North Atlantic Oscillation (NAO) and solar forcing over the past ~400years. Summer temperature variability affected both aquatic invertebrate groups in all study sites. The influence of NAO and solar forcing on aquatic invertebrates was also significant in the lakes except in the less transparent lake known to have remained uniformly cold during the past centuries due to…
Effect of complexing agents on phosphorus release from chemical-enhanced phosphorus removal sludge during anaerobic fermentation
2020
Phosphorus (P) release from sludge containing phosphate precipitates (FePs or AlPs) as well as the anaerobic performance with the addition of complexing agents (citric, tartaric and EDTA) during ambient anaerobic fermentation process were investigated. Results showed that citrate addition was the most effective method to enhance P release from inorganic phosphate by chelation and promote volatile fatty acids (VFAs) production simultaneously during anaerobic fermentation. Equimolar citrate addition with chemical precipitates was the optimal dosage. Microbial analysis revealed that EDTA has the strongest inhibitory effect on microbial activity and community structure, while citrate was more e…
Study on the effects of several operational variables on the enzymatic batch saccharification of orange solid waste
2017
In this work, batch enzyme-aided extraction and enzymatic saccharification of blade-milled orange waste was studied. The operation variables for this process were thoroughly analysed. It was determined that batch runs with initial pH values of 5.0 and 5.2 controlled during the first hour, 50°C and 300-500r.p.m. agitation resulted in the best yields, with a limited total and partial first-order enzyme deactivation (for cellulases and polygalacturonidase, respectively). Orange peel waste (OPW) at 6.7% w/w dry solid, 0.22 filter paper units (FPU)/g DS and proportional activities of other enzymes led to over 40g/L free monosaccharides and global yields to glucose over 80%. When using 10.1% w/w …
Bioplastic recovery from wastewater: A new protocol for polyhydroxyalkanoates (PHA) extraction from mixed microbial cultures
2019
Abstract A new protocol for polyhydroxyalkanoates (PHA) extraction from mixed microbial cultures (MMCs) is proposed. PHA-accumulating capacity of the MMC was selected in a sequencing batch reactor (SBR) fed with a synthetic effluent emulating a fermented oil mill wastewater (OMW). The highest recovery yield and purity (74 ± 8% and 100 ± 5%, respectively) was obtained when using NH4-Laurate for which operating conditions of the extraction process such as temperature, concentration and contact time were optimized. Best conditions for PHA extraction from MMC turned to be: i) a pre-treatment with NaClO at 85 °C with 1 h of contact time, followed by ii) a treatment with lauric acid in a ratio ac…
Designer ecosystems : A solution for the conservation-exploitation dilemma
2016
Increase in human population is accelerating the rate of land use change, biodiversity loss and habitat degradation, triggering a serious threat to life supporting ecosystem services. Existing strategies for biological conservation remain insufficient to achieve a sustainable human-nature relationship and this situation has fueled a debate on the conservation-exploitation dilemma. We need to devise novel strategies, in a mutually inclusive way, which can support biological conservation and secure economic development of deprived populations. Here we propose the use of designer ecosystems which can ensure ecological sustainability while providing ample and some new means of livelihood to loc…
Using foresight exercise to design adaptation policy to climate change: The case of the French wine industry
2018
Foresight studies are regularly conducted at sectoral or geographical scales, in order to help policy makers and economic actors to define their strategy of adaptation to climate change (CC). Some studies are rather “quick exercises”, in which a panel of experts is consulted to define the expected impacts of CC and to identify adaptation leviers for future policy. In other cases, a true foresight methodology is developed, leading to the building of scenarios based on : i) a systemic and participatory approach, ii) the definition of key variables, iii) the choice of assumptions and the coherent relations between these assumptions, the narrative description of scenarios. This participatory di…
Advanced methods of plant disease detection. A review
2014
International audience; Plant diseases are responsible for major economic losses in the agricultural industry worldwide. Monitoring plant health and detecting pathogen early are essential to reduce disease spread and facilitate effective management practices. DNA-based and serological methods now provide essential tools for accurate plant disease diagnosis, in addition to the traditional visual scouting for symptoms. Although DNA-based and serological methods have revolutionized plant disease detection, they are not very reliable at asymptomatic stage, especially in case of pathogen with systemic diffusion. They need at least 1–2 days for sample harvest, processing, and analysis. Here, we d…
Bacillus subtilis BS-2 and Peppermint Oil as Biocontrol Agents Against Botrytis cinerea
2019
Abstract The purpose of this study was to assess the activity of Bacillus subtilis BS-2 and peppermint oil against Botrytis cinerea. In this study parameters such as the age and the density of the bacterial culture and the incubation temperature were taken into consideration. Furthermore, the cellulolytic activity of the bacterium was determined. The effect of peppermint oil was evaluated at a concentration range of 0.5-4.0 %. The research was conducted with a dual culture plate method. The influence of B. subtilis BS-2 and peppermint oil on the growth of B. cinerea was evaluated based on the growth rate index. It was noted that the bacterial culture occurred at an initial density of OD 560…