A one dimensional moving bed biofilm reactor model for nitrification of municipal wastewaters.

This work presents a one-dimensional model of a moving bed bioreactor (MBBR) process designed for the removal of nitrogen from raw wastewaters. A comprehensive experimental strategy was deployed at a semi-industrial pilot-scale plant fed with a municipal wastewater operated at 10-12 °C, and surface loading rates of 1-2 g filtered COD/m d and 0.4-0.

Concentrations and fate of sugars, proteins and lipids during domestic and agro-industrial aerobic treatment.

This work investigates the composition and the fate of sugars, lipids, proteins, amino acids under aerobic conditions for 13 domestic and 4 agro-industrial wastewaters, sampled before and after treatment. The rates of aerobic degradation were moreover studied with a 21-day continuous aeration batch test. It is shown that the sum of the biochemical forms represented 50 to 85% of the total chemical oxygen demand (COD).

The role of loading rate, backwashing, water and air velocities in an up-flow nitrifying tertiary filter.

The vertical distribution of nitrification performances in an up-flow biological aerated filter operated at tertiary nitrification stage is evaluated in this paper. Experimental data were collected from a semi-industrial pilot-plant under various operating conditions. The actual and the maximum nitrification rates were measured at different levels inside the up-flow biofilter.

A biofiltration model for tertiary nitrification of municipal wastewaters.

The main objective of this work concerns the evaluation of the biological aerated filtration model found in GPS-X, which had never been evaluated with adequate data. This model is interesting since it integrates the physical and biological phenomena involved during filtration with a low complexity of use. The validation of the model parameters combines experimental and theoretical approaches.

Updated activated sludge model number 1 parameter values for improved prediction of nitrogen removal in activated sludge processes: validation at 13 full-scale plants.

The Activated Sludge Model number 1 (ASM1) is the main model used in simulation projects focusing on nitrogen removal. Recent laboratory-scale studies have found that the default values given 20 years ago for the decay rate of nitrifiers and for the heterotrophic biomass yield in anoxic conditions were inadequate. To verify the relevance of the revised parameter values at full scale, a series of simulations were carried out with ASM1 using the original and updated set of parameters at 20 degrees C and 10 degrees C.

Variability estimation of urban wastewater biodegradable fractions by respirometry.

This paper presents a methodology for assessing the variability of biodegradable chemical oxygen demand (COD) fractions in urban wastewaters. Thirteen raw wastewater samples from combined and separate sewers feeding the same plant were characterised, and two optimisation procedures were applied in order to evaluate the variability in biodegradable fractions and related kinetic parameters. Through an overall optimisation on all the samples, a unique kinetic parameter set was obtained with a three-substrate model including an adsorption stage.

Comparison of oxygen-transfer measurement methods under process conditions.

The objective of this paper is to compare the following four methods of measuring oxygen transfer in wastewater treatment plants under process conditions: the offgas, hydrogen peroxide (H2O2), reaeration, and in situ oxygen uptake rate (OUR) methods. Comparative tests were performed under controlled conditions in a pilot column and in six full-scale oxidation ditches equipped with fine-bubble diffusers and slow-speed mixers. The offgas and H2O2 methods give similar results (differences between the oxygen-transfer coefficients under field conditions [k(L)a(f)] from each method lower than 10%).