Industrial & Municipal WWT
Industrial Municipal WWT | Sludge | Drinking Water | Surface Groundwater |VOC Recovery | Defoamers | Amines | Analytical Laboratories
BOD and COD Removal
In aerobic biological waste water treatment processes, oxygen is fundamental to the effective removal of BOD and COD.
Positive Dissolved Oxygen levels must be maintained in any aerobic biological treatment plant in order to allow the biomass to metabolise BOD and COD optimally. Whilst aeration is commonly used, higher purity oxygen offers much higher rates of oxygen transfer and COD destruction than conventionally aerated systems.
Air Products’ Oxy-Dep processes have been developed to use oxygen in the activated sludge process (ASP) in the most efficient manner. The use of Oxy-Dep oxygen, or oxygen-air hybrid processes has massively increased the capacity of ASP for contaminant removal.
Membane Bio Reactors
Biological WWT with O2
Sequencing Batch Reactors
Waste Water Treatment with Ozone
In some instances, you may be faced with treating ‘difficult’ liquid wastes containing hard COD, AOX (Adsorbable Organic Halides), pesticides, colour and odour. Air Products has developed it’s CHEMOX ozone technology for the treatment of such contaminants and by utilising a unique, patented reactor design, the CHEMOX solution is an extremely cost effective approach to dealing with difficult contaminants. CHEMOX can be used either as pre-treatment prior to a biological process or as polishing after a biological process.
Improving biological treatment through toxicity removal
Improving metal precipitation by metal oxidation
Improving biodegradability by converting hard COD to BOD
Achieving discharge limits by eliminating recalcitrant COD,
colour, halogenated organics and red list substances
Carbon dioxide
Carbon dioxide is a colourless, odourless, non-flammable and slightly acid gas. It is produced by different processes in the petrochemical industry, or by natural gas combustion in cogeneration plants.
The main water treatment applications with CO2 are recarbonation and pH control. With the recarbonation process, the principal objective is to increase the hardness of potable water arising from a reverse osmosis process, maintaining the equilibrium between carbonate, bicarbonate and free carbon dioxide.
With pH control, the carbon dioxide acts as a mineral acid substitute for reducing the alkaline water pH, in accordance with the environmental rules. Carbon dioxide is less prone to overdosing than sulphuric and other mineral acids, and is safer to handle on site.
These applications are very interesting for all industrial sectors which have these needs. Air Products has important references in the food, petrochemical, textile, soap and pulp & paper industries, and in the public segment, drinking water and wastewater treatment plants.
Membrane Bio Reactors
Membrane Bio Reactors (MBRs) bring a new age of biological waste water treatment. With pure oxygen the benefits of MBRs are enhanced resulting in even higher rate biological treatment systems which provide compact control of COD, microorganisms and VOCs in waste water.
Oxy-Dep MBR can use high biomass concentrations, which for air-based systems cause oxygen transfer limitations. High purity oxygen resolves this, as well as the foaming and VOC issues associated with air-based systems.
High Treatment Rates (up to 35kgCOD/m³ /day)
Treatment of High Strength COD (20,000mg/l)
Minimal Sludge Production
Low VOC Emissions
Disinfected treated water
Sludge Treatment
Primary sludge and secondary sludge (from biological activated sludge plants) can be costly waste products from waste water treatment processes.
Most sludges consist, in part, of organic material which is amenable to degradation by microorganisms. This property can be used as the basis for treatment processes where oxygen supplied to the wet sludge promotes aerobic biological activity, and decomposition of the organic material to CO2 and water, so reducing the solids present in the sludge. This has the potential to save alternative sludge treatment or disposal costs.
High purity oxygen can be used successfully to accelerate Sludge Digestion, and, within the activated sludge process, to promote sludge digestion in situ.
The use of oxygen as opposed to air raises the temperature of an aerobic digestion process, leading to the easy maintenance of thermophilic conditions if required for sludge disinfection.
Aerobic Sludge Digestion
Membane Bio Reactors
Sequencing Batch Reactors
Retrofitting Jet Aerators with Oxygen
The treatment capacity of an existing wastewater system fitted with conventional (air based) Jet Aerators can be increased substantially by converting aerators to pure oxygen operation. This is usually a simple and inexpensive conversion.
The rate at which oxygen dissolves is proportional to the purity at which it is used. By changing from air to oxygen the purity increases five times giving much higher oxygen transfer rates.
A further benefit is the much reduced VOC stripping from the effluent system due to much lower volumes of gas leaving the basin.
Emergency Oxygenation
Dissolved Oxygen (DO) shortage can cause catastrophes in both natural waters and aerobic waste water treatment plants. In periods of high BOD and COD loading, or high ambient temperatures where biological activity and oxygen uptake rate are high, DO can fall to zero levels. At such times, higher aquatic life dies, odours can cause nuisance, and waste water discharges can exceed consent levels.
High purity oxygen brings immediate relief to oxygen shortfall. Air Products’ rapid response oxygen supply via Oxy-Dep jet mixing equipment or Fine Bubble Diffusers can be installed on site quickly and effectively, often within 48h of request.
Aerator Performance Testing
The performance of aeration equipment is critical to the successful operation of an activated sludge process. Often, in building a new plant, the performance of such equipment must be tested against the manufacturers specification in terms of power used for the quantity of oxygen transferred to the water.
Standard clean water Oxygen Transfer Efficiency (OTE) tests using nitrogen to purge oxygen out of the water, so reducing the Dissolved Oxygen (DO) concentration to zero, allow multiple tests to be carried out on new aeration equipment in a short time, giving data based on consistent methodology using a zero DO baseline.