In all industrial installations, from food & beverage to chemicals & petrochemicals, from textile to pulp & paper, Waste Water Treatment Plants (WWT) Plants (WWT) or Effluent Treatment Plants (ETP) are critical for their economy and efficiency. Industries are deemed responsible for the amount of fresh water they use and the quantity and quality of the waste water streams they return back to the environment into lakes, rivers or seas.
Complexity of Effluent Treatment Plants (ETP) depends on several factors. ETPs have to deal with a wide range of contaminated streams that could be:
- continuous – waste water from the process, blow-downs from boilers and cooling towers
- intermittent – regeneration water from demineralization plants, sewage from buildings and canteens, chemical drains, oily contaminated stormwater
- discontinuous – wash water from cleaning of tanks and vessels, bottom drainage of storage tanks, fire water
In relation with the specific industrial process, ETPs could face in principle an extremely heterogeneous chemical composition: vegetable or mineral oil and hydrocarbons, suspended solids, dissolved organics, chemical compounds difficult to be oxidised (phenols, polycyclic aromatic hydrocarbons, cyanide, benzene, toluene, xylene), acidic or alkaline chemicals, hydrogen sulphide and heavy metals.
Due to the variability of sources, of flow-rates, of chemical composition, Cannon Artes is capable of designing ETPs with the maximum flexibility. A sequence of several “unit operations” can be foreseen facing all the theoretical conditions without affecting reliability and performance.
In principle a typical ETP may be arranged on different sections:
- chemical physical treatment,
- biological oxidation,
- tertiary treatment and re-use.
Pre-treatment normally features well-designed equalisation sections that should be able to collect water of homogeneous chemical composition and cut any peak of flow and concentration. Pre-treatment also includes screening, neutralization (when required) and send separation. These treatments are necessary to preserve the unit and maximize the performance of the downstream process.
When oils and suspended solids (SST) are present, an oil separation section is foreseen. Oil and SST’s separation works on the difference in densities as the major driving force leading to the separation between oil and water. Cannon Artes is familiar with the state-of-art technologies in this field: API separators, Tilted Plates/Corrugated Plates Interceptors (TPI/CPI), Dissolved Air Flotation or Dissolved Gas Flotation.
Chemical physical treatment consists mainly in combining a chemical reaction with a separation by gravity. It is effective in removing suspended solids and heavy metals by means of coagulation and flocculation in order to destabilise and precipitate colloids and solids into a gravity settler or lamella-pack clarifier.
Biological Oxidation is definitely a key-step in waste water treatment since this is the way dissolved organic pollutants are oxidised to carbon dioxide and water. Furthermore, according to the influent nitrogen, phosphorous and carbon content, Cannon Artes’ designers are able to design the best solution: Extended Aeration, Membrane Bio-Reactor (MBR), Sequence-Batch Reactor (SBR), Moving-Bed-Bio-Reactor (MBBR).
For low to moderate capacities, Cannon Artes is able to provide the BIOCLAR biological treatment, a modularized biological solution combining the excellent performances in one compact prefabricated unit.
Finally because of the focus on water recovery, Cannon Artes is paying great attention to the tertiary treatment: thanks to the progress in membrane technology, re-use of treated waste water from the ETP’s is now on hand. In particular Microfiltration (MF) and Ultrafiltration (UF) are the most suitable solutions when quantitative removal of bacteria, fungi and suspended solids is mandatory.
Cannon Artes is also experienced with deionization of recovered waste water: Reverse Osmosis (RO) allows complete demineralisation and thus drives toward the Zero Liquid Discharge (ZLD) philosophy.