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ADVANCED DESIGN AND OPERATION OF MUNICIPAL WASTE WATERS TREATMENT PLANTS

Objective

TO CONTROL THE MICROORGANISMS STRAIN GROWTH, TO DECREASE THE ACTIVE REACTOR VOLUME AND TO REDUCE THE ENERGY CONSUMPTION FOR BUILDING WASTE WATERS TREATMENT PLANTS.
A new process called food mass control technology (FMCT) for the biological treatment of mixed wastewaters was investigated. FMCT is a modification of the activated sludge system which includes a large final settling tank to allow storage of biomass and control of the food mass (F/M) ratio under varying load conditions.

A pilot plant study was carried out at a full scale primary treatment plant, treating mixed wastewater in 2 parallel lines, one working with the conventional system and the other with the FMCT system. 7 intensive study periods were carried out covering a range of temperatures from 8 C to 23 C and F/M ratios from 0.15 to 0.60. At each temperature 2 different conditions of F/M ratio were tested. A large number of different parameters were measured and analyzed.

To verify and analyze the experimental data against the known theory, a dynamic simulation program, CAB, was developed. The process model used in CAB is based on an activated sludge model and the model for the secondary clarifiers on the flux theory adapted for use with activated sludge models. The data from 4 of the measurement periods were input to CAB for the modelling.

The effluent quality in both system was well within EC standards. Nitrification rates were low due to low alkilinity. The yield was highly influenced by temperature and F/M ratio. For similar F/M ratio the yield at 8 C was approximately twice the yield at 23 C.

The FMCT system gives:
better adjustment of biomass to instantaneous needs;
less occurence of bulking and foaming problems;
lower excess sludge volume;
more stable sludge with a lower percentage of volatile suspended solids.

The mathematical model has proved to be a valuable tool for the interpretation of experimental results and for the description of the actual settler performances of the biological reactors.
IN COLLABORATION WITH A DANISH LABORATORY MODELLING THE PROCESSES OCCURING IN TREATMENT PLANTS, THE SPANISH ORGANIZATION WILL PERFORM EXPERIMENTS IN TWO PARALLEL TREATMENTS FOR COMPARING THE CONSEQUENCES OF CHANGES OF A NUMBER OF PARAMETERS :

- VOLUME RATIOS OF INDUSTRIAL AND DOMESTIC WASTE WATERS TO BE TREATED
- CONCENTRATION OF BIOMASS
- TEMPERATURE AND MIXING OF WATERS
- BACTERIA STRAINS

THE RESULTS ARE EXPECTED TO FORM THE BASIS FOR MODELLING THE OPERATION AND DESIGN OF FULL SCALE TREATMENT PLANTS, AND FOR CONTROLLING THEIR OPERATION CONDITIONS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Ente Vasco de la Energía
Address

48001 Bilbao
Spain

Participants (1)

DANMARK TEKNISKE HOJSKOLE
Denmark
Address

Lyngby