Moroccan dairy installs energy-efficient wastewater treatment with water recycling
Ensures compliance with legal requirements, odour suppression and water recycling for irrigation
What we did
A wastewater treatment plant with water recycling was installed in a milk derivatives production site in Morocco which mainly processes milk and yoghurt. The objective was to ensure compliance with the legal requirements for discharge into the local sewage system. Moroccan regulations are primarily concerned with temperature, pH, COD, BOD5, fats, and solids content. Build-up of odours is also to be suppressed and the treatment should be designed to be as sustainable as possible.
Objective
Processing milk produces large quantities of fat and other organic residues. Some of this ends up in the production wastewater which can lead to unpleasant odours. The resulting sludge gas and decomposition products can lead to damage to the municipal sewage system and its ecosystem.
A wastewater treatment plant is to be planned and built which will safely reduce the very high organic wastewater load to the required threshold values despite the limited available space. It is not unusual for the daily wastewater quantities and loads from production to vary from day to day. In addition to this, there should be no build-up of odours from the plant solution and the sludge treatment should achieve a specified dry matter content.
Solution
To meet the objectives, EnviroChemie planned, installed and commissioned a multi-stage plant solution.
A high-performance screen filter removes the solids from the daily wastewater quantities. These solids are subsequently stored in a buffer tank. A Flomar® dissolved-air flotation system then removes the inorganic and organic wastewater components, effectively and economically reducing the wastewater contamination load. Chemical-physical conditioning is provided upstream of the continuously operating flotation stage. This removes up to 98% of the solids and fats and up to 60% COD.
The wastewater is then sent to a Biomar® OKB (Oxygenating Compact Biology) aerobic reactor where the COD and BOD load is reduced further. The Biomar® OKB technology makes use the ability of naturally growing organisms to convert contaminants, pollutants or impurities in the wastewater into biological sludge or to remove them. A fine-bubble diffuser ensures continuous aeration in the activation plant. The necessary oxygen is delivered as atmospheric oxygen by a phased blower station. The warmed air is fed through pipes into the aeration cells laid along the bottom.
The biosludge settles in the post treatment facility which is located in the centre of the activation container. From there, most of the settled sludge is then returned radially to the aeration tank by means of an adjustable hyperboloid stirrer. Some of it accumulates as excess sludge and is removed. The removed sludge is finally dewatered by a screw compactor.
The buffer tank, sludge tank and flotation system are covered. Gases which occur are extracted and fed into the biological process to break down the odour molecules. The plant is completely automated and all the motors have frequency converters to optimise energy consumption.
Benefits
The recently installed, energy-efficient plant solution for wastewater treatment easily meets all the required purification goals (see Table 1). Odours are also effectively suppressed. A high degree of dewatering is achieved by the sludge treatment process with a dry matter content of approximately 25% TS.
All of the treated water is used for irrigation and cleaning the property or for washing HGVs.
EnviroChemie's subsidiary in Morocco supplies the water chemicals to operate the plant as well as customer service and provision of spare parts, ensuring the customer can always contact a local expert.
