One-year operation of single household membrane bioreactor plant

This paper evaluates the results from a 12-month study of a single-household wastewater treatment plant with submerged membrane module (household MBR plant) that was monitored from winter to winter season. The samples were collected at least twice a week (an intensive research study at real conditions). The household MBR (membrane bioreactor) plant was linked to a family house with 4 residents. In this study the treatment plant was fed by real domestic wastewater. In contrast to most other experiments with small-scale WWTPs (wastewater treatment plants) carried out in laboratories and facilities of large municipal WWTPs (polygons) which guarantee stable and flexible operation but the characteristics of wastewater and activated sludge in these studies usually differ from those that occur in real small-scale/single-household WWTPs. One of the main goals of this research was to test the response of membrane and activated sludge to different conditions during real operation of the household MBR plant, such as a long period of zero influent/load, or vice versa the presence of a large amount of concentrated wastewater (e.g. during the weekend), very low winter temperatures (water temperature below 5–6°C), high pH values, and the presence of domestic detergents.</jats:p

Influence of Combined Suspended and Fixed-Film Biomass in Anoxic Reactor on Nitrification-Denitrification Process

In single-sludge nitrification-denitrification process biomass is passed periodically through oxic and anoxic reactors. Nitrifying bacteria need oxygen for substrate oxidation. Behavior of these bacteria under anoxic conditions is still not sufficiently known. In this paper influence of retention time in anoxic reactor on nitrifiers has been studied. Optimum retention time for tested biomass was found to be 3 hours. A possible way to set-up this retention time is to increase denitrification rates by addition of support material of fixed-film biomass to anoxic reactor (e.g.polyurethane cubes). Increased denitrification rate results in decrease of necessary volume of anoxic reactor followed by increase of nitrification efficiency. Presence of fixed-film biomass has no influence on clarifier capacity and oxygen concentrations in oxic reactors. Theoretical aspects of this modification were confirmed in laboratory models with synthetic wastewater as substrate.</jats:p

The influence of cadmium on activated sludge activity

The influence of solid retention time, cadmium loading and the effect of the process of acclimation on the activity of activated sludge in the presence of the metal were studied. Activated sludge was cultivated in plug-flow and continuous completely mixed lab-scale bioreactors. Respirometric measurements were applied to evaluate the inhibition effects of cadmium on activated sludge. Monod's equation and the equation of non-competitive inhibition were applied to describe the toxicity and inhibition of cadmium. Maximum inhibition effect of cadmium was observed at different time periods of cadmium acting on both acclimated and non-acclimated sludges. The dependence of the attainment of maximum inhibition effect on the metal loading as well as solid retention time was observed. Therefore, maximum inhibition should be included in the assessment of metal toxicity.</jats:p

Nitrogen removal from wastewater of the chemical company Duslo

The results of laboratory scale modelling and real scale performance of the pre- and post-denitrification of a wastewater from the production of industrial fertilizers, pesticides and rubber additives are presented. As a substrate for the pre-denitrification, the biologically degradable organic compounds present in the influent were used. Selected wastewaters from chemical industry were used as a substrate for the post-denitrification. The results of the laboratory scale research of the pre-denitrification were successfully verified in real scale, an efficiency of 97% and 88% was reached for the removal of NO2––N and NO3––N respectively. The efficiency of the post-denitrification in real scale was 15% from the entering amount of NOx––N (NO2––NO3––N). Pre-denitrification removed about 190 kg NOx––N and post-denitrification about 85 kg NOx––N daily.</jats:p