Theoretical data vs. Practical data
The design of a wastewater treatment plant cannot always be based on assumptions and theoretical formulas. Sometimes it’s strictly necessary to design a system based on practical data. This is especially the case with more complicated, to be purified waste waters.
First of all, the seemingly best technical concept is established based on a desk study for the treatment of a particular waste water stream. Thereafter, the technical feasibility of this concept will be tested by laboratory tests. If the laboratory tests show that it is technically possible to treat specific waste water, laboratory tests can be reproduced on a pilot scale. This will allow the verification of the technical feasibility of the proposed concept in real conditions. The influence of the variations in the composition of the waste water in the purification process may in particular be determined during the pilot tests. Furthermore, the boundaries of the process parameters can also be defined under real conditions.
With the information collected during the laboratory and pilot tests, a basic engineering study can be performed. An estimate of the required budget according to certain accuracy, as well as the required technical data is provided to develop the OSBL scope and continue to deal with detailed engineering.
One of our customers from the chemical industry disposes of a wastewater stream consisting largely of methanol, which is easily biodegradable. Through an expansion of the production capacity, a substantial increase in the organic load of the existing water treatment was expected.
The initial idea of the customer was to make a copy of the existing aerobic wastewater treatment in order to double the capacity. However, after a more detailed analysis of the composition of the different waste water streams, we proposed to isolate the highly concentrated methanol stream and to treat it separately as to make room for the additional organic load of the existing water treatment by mean of production expansion.
The pre-treatment of the highly concentrated methanol stream was proposed to be treated anaerobically. An anaerobic pre-treatment offers the advantage of a compact plant, as well as low operating costs.
This picture below represents a pilot plant that was used for the on-site pilot testing. This construction determined the nominal and maximum process parameters, such as load, temperature, up-flow, …
Estimation of required budget
Based on the data collected during the pilot test, a ± 10% estimate was made of the required budget for the anaerobic pre-treatment. Compared to doubling the aerobic treatment capacity was thus a saving of 30% on the investment cost. Besides, the operating costs drastically decreased due to the anaerobic pre-treatment compared to a greater aerobic purification station.
With each project, SUEZ tries to re-develop the optimal technical concept to achieve the lowest possible total cost of ownership. For this we have a number of pilot plants that can be used to test our concepts to reality. It is both a pilot plant for anaerobic treatment, as for physico-chemical, aerobic, as tertiary treatment or recycling.