Search results for "Nitrification"

Nitrogen cycling microbial communities: from diversity to interactions and functions

2019

Soil microorganisms form one of the largest biodiversity reservoirs on earth. They also play essential roles in ecosystem functions such as biogeochemical cycling. However, the importance of microbial community diversity and composition for ecosystem functioning is still debated. A sound understanding of the ecological processes governing the assembly of these communities in the environment is also missing. In this talk, I will give examples of how we addressed these knowledge gaps using nitrogen cycling microorganisms as model functional guilds. Nitrogen is the most limiting nutrient for crop production in agriculture. The nitrogen cycle is also one which was pushed by human activities out…

Traking nitrate reducers and denitrifiers in the environment

2005

The ability to respire nitrate when oxygen is limited has been described in taxonomically diverse microorganisms including members of the alpha-, beta-, gamma- and epsilon-proteobacteria, high and low GC Gram-positive bacteria and even Archaea. Respiratory nitrate reduction is the first step of the denitrification pathway, which is important since it is the main biological process responsible for the return of fixed nitrogen to the atmosphere, thus completing the nitrogen cycle. During the last decade, considerable knowledge has been accumulated on the biochemistry and genetics of the nitrate reductases. In this paper, we summarize the recent progress in molecular approaches for studying th…

Impact des systèmes de culture en protection intégrée contre les adventices sur l'intensité des émissions de N2O par les sols

2013

Modélisation de l’effet des apports d’effluents porcins sur la dénitrification et les émissions de protoxyde d’azote

2007

EA

Activity, size and structure of the nitrate reducer community in relation to land-use and fertilization regime in Madagascar

2007

Communication orale, résumé; absent

Spatial distribution of ammonia-oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning

2011

Characterization of spatial patterns of functional microbial communities could facilitate the understanding of the relationships between the ecology of microbial communities, the biogeochemical processes they perform and the corresponding ecosystem functions. Because of the important role the ammonia-oxidizing bacteria (AOB) and archaea (AOA) have in nitrogen cycling and nitrate leaching, we explored the spatial distribution of their activity, abundance and community composition across a 44-ha large farm divided into an organic and an integrated farming system. The spatial patterns were mapped by geostatistical modeling and correlations to soil properties and ecosystem functioning in terms …

The effect of plants on microbes, water quality, and fish performance in an aquaponic system

2023

Aquaponics is a way to utilize the nutrient-rich effluents from recirculating aquaculture systems (RAS) by combining hydroponics, i.e. soilless plant farming, with RAS. The plants in aquaponics can be grown as a single or mixed plant species together with fish. In this dissertation, I investigated if plant growth is affected in aquaponics compared to hydroponics and if the plants affected the growth and microbial communities in rainbow trout (Oncorhynchus mykiss) or water quality in aquaponics compared to RAS. The first experiment was conducted by pairing lettuce (Lactuca sativa) with mint (Mentha spicata), rucola (Diplotaxis tenuifolia), or wormwood (Artemisia absinthium) and growing them …

Evaluation of biomass activity and wastewater characterization in a UCT-MBR pilot plant by means of respirometric techniques

2011

Abstract Over the last two decades, Membrane Bioreactors (MBRs) emerged even more for wastewater treatment, ensuring high removal efficiencies as well as very small footprint requirements. Indeed, in this kind of process, a modification in biomass activity and viability can exist compared to that of a CAS process. In this context, respirometric analysis represents a reliable tool in order to evaluate the actual biomass kinetic parameters, to insert in mathematical models in the design phase, as well as to monitor the biomass viability, especially when these processes are operated with high SRT values. The paper presents some results of respirometric techniques applied for the characterisati…

Design of nutrient removal activated sludge systems

2003

A mechanistic mathematical model for nutrient and organic matter removal was used to describe the behavior of a nitrification denitrification enhanced biological phosphorus removal (NDEBPR) system. This model was implemented in a user-friendly software DESASS (design and simulation of activated sludge systems). A 484-L pilot plant was operated to verify the model results. The pilot plant was operated for three years over three different sludge ages. The validity of the model was confirmed with data from the pilot plant. Also, the utility of DESASS as a valuable tool for designing NDEBPR systems was confirmed.

Performance of a hybrid activated sludge/biofilm process for wastewater treatment in a cold climate region: Influence of operating conditions

2013

a b s t r a c t The main aim of the study was to investigate a hybrid MBBR process, mostly in terms of organic matter removal and nitrification, when operating with different values of the mixed liquor sludge retention time (SRT), and highlighting the influence of temperature on the process. Based on experience in practice it was hypothesized that nitrification could be maintained at far lower SRT's than in conventional activated sludge systems and with high organic loading rates applied. A field gathering campaign has been carried out on a hybrid activated sludge/biofilm. The obtained results highlighted that the pilot plant was capable to remove the organic matter at loading rates up to 3…