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Treatment of high organic load, high temperature and high salinity industrial waste water containing recalcitrant contaminants

Final Report Summary - PROMETHEUS (Treatment of high organic load, high temperature and high salinity industrial waste water containing recalcitrant contaminants)

The PROMETHEUS project addressed a critical economic, environmental and legislative problem of the European industry on rubber and aluminium production consisting on the treatment of high organic load and high temperature industrial waste waters containing recalcitrant contaminants originated from injection / extrusion and post-washing processes in aluminium and rubber parts production industries.

The production process of both aluminium and rubber parts (particularly for use in automotive applications) requires injection / extrusion demoulding and parts post-washing processes that generate waste water where the main contamination originates from demoulding agents causing high chemical oxygen demand and high temperatures. Both industries face the same problems as they use similar chemical demouldants and similar techniques for the demoulding / injection processes.

PROMETHEUS waste water treatment system treats these waste waters to achieve the recovery of high purity water and chemicals (demoulding agent used in injection processes) for re-use plus a final effluent that meets EU discharge requirements; there is also a 99 % reduction in the amount of waste water requiring off-site treatment.

There is currently no system in the market allowing for this. PROMETHEUS is a competitive opportunity to export a new technology that addresses all these issues.

Project context and objectives:

The aim of the PROMETHEUS project was to design an integrated process able to treat high organic load (high chemical oxygen demand, COD) waste waters with the multiple goals of:

(a) reducing pollution to the environment;
(b) obtaining re-usable water (to be re-incorporated to the process);
(c) recovering and re-using costly chemicals (demoulding agents); and
(d) reducing waste disposal volumes / costs by a novel concentration of the final waste.

The global PROMETHEUS objective is to implement a new waste water technology treating waste water from injection and extrusion and washing processes in aluminum and rubber parts producing industries (high in COD) in such a way that:

- 99.5 % for aluminum industries and 95 % for rubber industries of high quality water is recovered for re-use,
- 99 % reduction of waste for off-site treatment is achieved for both the aluminum and rubber industries.

The PROMETHEUS solution is based on a nanofiltration membrane followed by an evapourator:

- nanofiltration membrane treatment in order to separate the demoulding agent from the waste water obtaining a concentrated effluent and water with high salinity,
- evapourator treatment for further concentration obtaining water for re-use, minor volume of water for disposal and a low volume waste for off-site disposal and management.

The best compromise on energy costs and optimisation of membrane / evapourator cleaning procedures has been reached thanks to the modelling and optimisation of the system behaviour controlled completely via an automatic electronic control system.

On the membranes side, the electronic control system allows to maintain a fixed flux of wastes through the membrane, allowing the membranes to work in the best conditions. In this case, the high temperatures (> 25oC) effects become insignificant and the membrane can be operated continuously for over 24 hours. Just some organic fouling from the polymeric demoulding agents is deposited and a frequent flushing (typically 5 sec/min) must be performed to maintain the sustainable membrane performance and lifetime.

The evapourator performance has been significantly improved thanks to the electronics control of all the parameters: temperature, flow and level of water inside the evapourator.

The PROMETHEUS solution has been developed and tested firstly at lab-scale and finally industrially validated and optimised in a semi-industrial pilot plant in the facilities of Cikautxo rubber processing company located in Berriatua (Bizkaia), Spain.

The technical objectives aimed during the pilot study were the following:

- To maintain a competitive membrane flux with desired cleaning frequencies. On rubber industry, the membrane can be operated continuously at fixed flux for over 24 hours if the nanofiltration membrane flux is maintained at a certain level that depends on ceramic or nanofiltration membranes. Daily cleaning is required in all cases.
- To meet the industrial water reuse standards or discharge standards. On rubber industry, the membranes can reject over 95 % of COD and the permeate can be either discharged or reused as boiler feed water if total hardness is further reduced. On aluminium industry, there is a potential for water reuse in the factory that needs further study.
- To achieve desired evapourator performance with membrane-concentrated feed solution; on rubber industry, a slightly better performance has been achieved. However on aluminium process, degraded evapourator performance has been observed.
- To minimise energy input to the integrated systems. 55 % energy saving is obtained with the membranes integration on rubber industry. On aluminium industry, significant energy savings are obtained with a two-stage nanofiltration design.
- To achieve at least 95 % of water recovery. An overall water recovery of > 99 % has been achieved on rubber industry and > 97 % on aluminium industry.
- To reduce amount of waste for off-site treatment; Evapourator retentate waste for disposal has been reduced to < 1 % on rubber industry and to 2.9 % on aluminium industry.

In conclusion, the pilot study has successfully validated that the PROMETHEUS solution can solve the rubber wastewater problems with great operational savings, and can potentially provide a valid solution to the aluminum wastewater treatment.

Project results:

The PROMETHEUS project has identified and developed an effective treatment process as a solution to treat high organic load (high chemical oxygen demand (COD)) by implementing membrane separation of demoulding agents with a subsequent evapouration cycle. This process has been assessed as cost-efficient taking into account existing practice and the environmental benefits from water reuse, the recovery of chemicals and reducing waste disposal volumes.

The scientific and technical objectives of the project have been fully met. The overall system includes the selection of suitable membranes, fouling prevention, selection and design of evapourator, and integration and validation through the use of modelling and electronics control system.

Technical objectives achieved are:

- highly flexible system,
- suitable for variable concentration of demoulding agent in the waste water,
- high efficient elimination of COD,
- high efficient concentration of effluent,
- recovery of high quality water for re use,
- suitable control for continuous operation,
- optimisation to reduce fouling,
- optimisation of the washing system,
- resistant to high temperatures operation,
- reduction to 1% of residue for off site disposal,
- minimised energy consumption.

Potential impact:

Aluminium and rubber production are important economic activities in Europe. The PROMETHEUS solution will find its application in SME-rubber and SME-aluminium industries in Europe safeguarding or creating jobs, especially in view of growing competition from low-wage paying industries in China.

PROMETHEUS is fully in line with the European Water Directives, providing aluminium and rubber SMEs with an effective tool to comply with waste water treatment requirements. In addition, through the re-use of water, the intense strain on water resources in Europe can be partially relieved.

PROMETHEUS will help to improve the quality of life by reducing pollution in areas were less effective waste water treatments are used at present. Eliminating pollutants, like demoulding agents, effectively at source will also contribute towards higher standards of health and safety, especially in view of wildlife in rivers and seas and the prevention of pollution in drinking water sources.

The pilot study performed at Cikautxo facilities has fully validated the PROMETHEUS system. The technical solution combining nanofiltration and ceramical membranes in the case of aluminium waste water, or just nanofiltration in the case of rubber waste water, and evapouration technologies was completely developed and tested. The data generated in the pilot study under field testing conditions were used for the development and optimisation of mathematical models for nanofiltration membranes and evapourators. that can be used in control systems to optimise the processes for large scale applications.

The project has generated new technical developments that will increase participant SME competitiveness in the market. Final product allows meeting the European directives in terms of water reuse and cleaning, and also management of wastes waters to be converted in valuable by products. Rubber and aluminium industries will benefit from the results of this project since these results will solve the problem of management of the wastes generated.

Project coordinator:
Mr Javier Bernad (Sales manager)
Tecnicas de la automatizaci?n COHAN S.L.
Calle San L?zaro SN 26500 Calahorra, Spain
Tel.: +34-941-136076
Fax: +34-941-136077

PROMETHEUS project website: