This paper aims to explain results of respirometry experiments using Activated Sludge Model No. 1. In cases of insufficient fit of ASM No. 1, further modifications to the model were carried out and the so-called "Enzymatic model" was developed. The best-fit method was used to determine the effect of the proposed modifications. Increased agreement was found between simulated data and respirometry results, particularly for repeated respirometric tests with acetate as the sole substrate. Additionally, the influence of different biomass pre-conditioning methods was examined. Results from repeated respirometric tests suggest that presence of residual products in an activated sludge sample before respiration testing may decrease the sample's activity and significantly affect results from respirometric tests. An innovative approach to recover original activity is suggested by washing activated sludge samples with tap water or "mineral medium". As allylthiourea (ATU) was used in most experiments to suppress endogenous nitrification, its influence on kinetic parameters was reviewed. Respirometric tests confirmed that ATU addition has a significant effect on activity and respiration rate of activated sludge samples and could affect results of respirometric analyses.
- MeSH
- biomasa MeSH
- kyslík analýza metabolismus MeSH
- odpad tekutý - odstraňování * MeSH
- odpadní vody mikrobiologie MeSH
- teoretické modely * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyslík MeSH
- odpadní vody MeSH
The influence of industrial (pharmaceutical and chemical) wastewater composition on membrane bioreactor (MBR) performance was investigated in a pilot-scale installation. The study focussed on nitrification performance, which was evaluated based on influent and effluent parameters as well as batch nitrification rate tests. The industrial wastewater was pumped into the MBR in a mixture with municipal wastewater at constant flow rate. The loading of the MBR with industrial wastewater was increased stepwise from 0 to 75% share in the mixed influent to study the adaptation of nitrifying bacteria. Stable nitrification performance was observed until the content of industrial wastewater in the influent reached 40%, with effluent values of around 0.56 mg L(-1) NH4-N and 98.3% ammonia removal. Breakdown of nitratation was observed at a 40% industrial wastewater dose and breakdown of nitritation at a 50% dose, respectively. However, after several months of adaptation, both processes recovered. No nitrification was observed when the industrial wastewater share exceeded 50%. Adaptation of nitrifying bacteria in the MBR was also confirmed by results of kinetic tests. The inhibition effect of the concentrated industrial wastewater to the MBR sludge decreased substantially after several months of exposure, while the inhibition of referential activated sludge remained constant.
- Klíčová slova
- ATU, AUR, Activated sludge, Adaptation, COD, EPS, F/M, HRT, IWW, Industrial wastewater, Inhibition, MLSS, MWCO, Membrane bioreactor, N(T), Nitrification, OUR, P(T), PES, PVDF, SMP, SRT, TMP, allylthiourea, ammonia uptake rate, chemical oxygen demand, extracellular polymeric substances, food to microorganisms ratio, hydraulic retention time, industrial wastewater, mixed liquor suspended solids, molecular weight cut-off, oxygen uptake rate, polyethersulfone, polyvinylidene fluoride, sludge retention time, soluble microbial products, total nitrogen, total phosphorus, transmembrane pressure,
- MeSH
- bioreaktory * MeSH
- čištění vody * MeSH
- dusík izolace a purifikace MeSH
- filtrace MeSH
- membrány umělé * MeSH
- měření biologické spotřeby kyslíku MeSH
- nitrifikace * MeSH
- odpad tekutý - odstraňování MeSH
- odpadní voda MeSH
- odpadní vody chemie MeSH
- permeabilita MeSH
- pilotní projekty MeSH
- průmyslový odpad analýza MeSH
- velkoměsta MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- velkoměsta MeSH
- Názvy látek
- dusík MeSH
- membrány umělé * MeSH
- odpadní voda MeSH
- odpadní vody MeSH
- průmyslový odpad MeSH
BACKGROUND AND AIMS: Selected beneficial Pseudomonas spp. strains have the ability to influence root architecture in Arabidopsis thaliana by inhibiting primary root elongation and promoting lateral root and root hair formation. A crucial role for auxin in this long-term (1week), long-distance plant-microbe interaction has been demonstrated. METHODS: Arabidopsis seedlings were cultivated in vitro on vertical plates and inoculated with pathogenic strains Pseudomonas syringae pv. maculicola (Psm) and P. syringae pv. tomato DC3000 (Pst), as well as Agrobacterium tumefaciens (Atu) and Escherichia coli (Eco). Root hair lengths were measured after 24 and 48h of direct exposure to each bacterial strain. Several Arabidopsis mutants with impaired responses to pathogens, impaired ethylene perception and defects in the exocyst vesicle tethering complex that is involved in secretion were also analysed. KEY RESULTS: Arabidopsis seedling roots infected with Psm or Pst responded similarly to when infected with plant growth-promoting rhizobacteria; root hair growth was stimulated and primary root growth was inhibited. Other plant- and soil-adapted bacteria induced similar root hair responses. The most compromised root hair growth stimulation response was found for the knockout mutants exo70A1 and ein2. The single immune pathways dependent on salicylic acid, jasmonic acid and PAD4 are not directly involved in root hair growth stimulation; however, in the mutual cross-talk with ethylene, they indirectly modify the extent of the stimulation of root hair growth. The Flg22 peptide does not initiate root hair stimulation as intact bacteria do, but pretreatment with Flg22 prior to Psm inoculation abolished root hair growth stimulation in an FLS2 receptor kinase-dependent manner. These early response phenomena are not associated with changes in auxin levels, as monitored with the pDR5::GUS auxin reporter. CONCLUSIONS: Early stimulation of root hair growth is an effect of an unidentified component of living plant pathogenic bacteria. The root hair growth response is triggered in the range of hours after bacterial contact with roots and can be modulated by FLS2 signalling. Bacterial stimulation of root hair growth requires functional ethylene signalling and an efficient exocyst-dependent secretory machinery.
- Klíčová slova
- Arabidopsis, Flg22, Pseudomonas, Root hair, dde2/ein2/pad4/sid2, exocyst, vesicle trafficking,
- MeSH
- Arabidopsis genetika růst a vývoj mikrobiologie MeSH
- genový knockout MeSH
- interakce hostitele a patogenu * MeSH
- kořeny rostlin růst a vývoj mikrobiologie MeSH
- mutace MeSH
- proteinkinasy genetika MeSH
- proteiny huseníčku genetika MeSH
- Pseudomonas syringae * MeSH
- receptory buněčného povrchu genetika MeSH
- regulace genové exprese u rostlin MeSH
- signální transdukce MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- EIN2 protein, Arabidopsis MeSH Prohlížeč
- EXO70A1 protein, Arabidopsis MeSH Prohlížeč
- FLS2 protein, Arabidopsis MeSH Prohlížeč
- proteinkinasy MeSH
- proteiny huseníčku MeSH
- receptory buněčného povrchu MeSH
