Detailed case study, available only by request from our existing reps or contacts.
Please contact Georgina Porro: giorgina@cgdepur.it to inquire about this case study
Detailed case study, available only by request from our existing reps or contacts.
Please contact Georgina Porro: giorgina@cgdepur.it to inquire about this case study
The Application of C&G Vacuum Evaporators in Surface Finishing Industries
The galvanic industry, with its surface treatments, generates a polluted wastewater which cannot be discharged into the environment.
C&G has over 30 years experience in this sector. In the 1970s we developed the technology of “zero discharge” to resolve the problems galvanic companies were facing around Firenze of water shortage in the summer months and to respect the stringent environmental laws regarding discharge into the environment.
The choices in a galvanic factory are fundamentally three:
- No ionic exchange system is present,
- a)When the water contains cyanide without chrome: all the discharge water is pre-treated to bring it to a pH of about 10.5 or11 and cyanide is removed through oxidation using NaClO2(sodium hypochlorite). It is then precipitated, decanted, neutralised and sent to a vacuum evaporator, to be able to re use the distillate water. With a plant of 20000 litres/day wastewater, about 1000 litres of concentrate will have to be taken away for disposal while 19000 litres of pure water will be available for re use.
- b)When the water contains chrome without cyanide:all the discharge water is pre-treated to bring it to a pH of about 2.5 or 3, and chrome is reduced from Hexavalent Cr to Trivalent Cr through Na 2 S 2 O5 (Sodium disulphite). It is then precipitated, the pH is brought to 8.5 or 9 , it is decanted, neutralised and sent to a vacuum evaporator, and the distillate water can be re-used. Again with a plant of 20000 litres/day wastewater, about 1000 litres of concentrate will have to be taken away for disposal while 19000 litres of pure water will be available for re use.
- The use of an ionic exchange system to treat the water from the various washes, which allows a better quality and quantity of water for the galvanic washes. The eluates from the regeneration of the ionic exchange system are treated following the above distinction between the cyanide and chrome waters. They are then sent to the vacuum evaporator, so the final discharge is guaranteed to be within all environmental limits for whatever final use is foreseen for it. The concentration of the regeneration water is about 20 times. Therefore using an ionic exchange system combined with a final evaporator 100% of the water used in the process can be recuperated, thus guaranteeing a constant high level of clean water for the rinses, and a constant quality of product. However, we cannot recover the raw materials present using this system, as the eluates from the regeneration contain not only the raw material but other salts and pollutants in general.
- Raw materials such as nickel, chrome and copper are very expensive today, and the tendency in Europe is to design factories that allow a total recovery of both the raw materials used and the process water. A vacuum evaporator allows this, but it is essential to know the layout of the industrial line. A separate smaller evaporator is placed on the various lines, chrome, copper, zinc and nickel, so that the material can be completely recovered. This allows a recovery of the investment in a short time, as the customer saves not only on the cost of the raw material recovered, but also on the cost of the chemical-physical wastewater treatment present.
It should be noted that the economic return depends on the level of drag-out present: the higher the value, the sooner the purchase costs of the vacuum evaporator will be covered.
Rules and regulations in act do not allow the water from the graphic arts industry to be discharged into the environment. This is an important problem for these companies which are obliged to send the effluent away using specialised companies, with a high disposal cost.
C&G has been highly specialised in this field since 2004, and today the customer is advised to use a system of decantation . agitation – evaporation – oxidation when treating such water.
The process includes a first stage of decantation which separates the larger particles through gravimetric force. The water is then sent to a section for agitation using an injection of air to oxidize and /or strip any eventual presence of volatile composites such as solvents and/or ammonia. The pre-treated solution is then sucked in by effect of depression to our evaporation system, which effects the recovery of the distillate and the consequent concentration of the effluent. The distillate can be reintroduced into the productive cycle without undergoing any other treatment, and is used in particular for clearing purposes of the machinery used. Otherwise it can be discharged to the drains after an oxidation treatment to reduce any remaining COD.
Liquids which are treated using this process system include all the effluents that contain water based inks, developing liquids, detector liquids, and traces of solvents.
Such an effluent is made up of a turbid, coloured water loaded with non aggressive organic substances. The distillate obtained is limpid and colourless, although in some cases the presence of organic substances might make it unsuitable for direct discharge into the sewers.
The low quantity of daily effluent present in a typical industry of graphic arts allows the use of vacuum evaporators with a “dry” technology, which gives a mud/powder as the final refuse to dispose of. This is an advantage as in many countries the disposal of a mud is more economically convenient than the disposal of a liquid..
A client in Spain was awarded an environmental prize for the application of C&G machinery and technology in this field. He covered the purchase costs of the machine in under two years, and uses the distillate for sanitary purposes in his graphic arts company.
This application of vacuum technology allows the characteristics of a particular grape must to be enriched and to remain absolutely the same at every vintage, irrespective of weather conditions, guaranteeing the enrichment of all the organoleptic characteristics of the wine being made.
Characteristics of the BACCO Series:
- Low operation temperature: 20-22°C
- Fully automatic working cycle, controlled by a simple digital programmer
- Very low noise level
- Very compact and easily transported
- Low energy consumption: average 150 Watts/litre of water evaporated
- Boiler and framework constructed in stainless steel AISI 304
- Capacity: ranging from 250 litres/24 hours to 5000 litres/24 hours of evaporated water
Standard BACCO Series:
H20 in 24 Hr Cons-Kw Dimension
BACCO-8 800 7.5 800x2000x2200H
BACCO-14 1500 12 1250x2500x2300H
BACCO-30 3000 28 1500x3000x2300H
BACCO-50 5000 36 1500x3000x2300H
Example:
To increase the alcohol proof of a must by 1% it is sufficient to evaporate 10% of the H2O:
1000 litres of a must at 10% proof can be reduced to 900 litres of a must at 11% proof and 100 litres of water.
The sector and activities of chemical industries normally produce a wastewater from the washing of the equipment used in their production.
This effluent contains parts of the manufactured product and cannot be discharged into the environment. The washes of paints or soaps can be taken as an example.
Vacuum evaporation is an effective and efficient way of treating such effluents, as their very high COD parameter does not allow the water to be discharged. The water obtained through evaporation can be used again for all the internal washing processes in the industry, while the concentrate containing the pollutants is disposed of by specialized companies
The industrial sectors with effluents that can contain oily emulsions can be divided into two groups:
– Mechanical/automobile sector
– Petrol-chemical industry
Current environmental rules and regulations do not allow the discharge of oily fluids such as oily emulsions, exhausted oils, those from degreasing processes or thermal treatments, into the environment. They must be treated and removed as contaminated refuse with all the related costs.
The percentage of oil present in the water concentrates from an initial 2-5% to arrive at 55-60%. Although it is possible to reach a higher concentration, this does not result convenient from an economic point of view. This is due to the fact that the disposal costs for a concentration of oil at about 50% are similar to those for non concentrated emulsions. Above this limit the disposal costs result considerably higher.
Treating this effluent with a vacuum evaporator, it is possible to reduce the volume of wastewater up to 90-95%, and a distillate is obtained which can be used as washing water.
The quality of the distillate obtained in many cases has chemical-physical characteristics which are not suitable for discharging into the sewers, and it is therefore necessary to re-use it as industrial water for internal purposes in the factory.
Frequent solutions are:
– to use the distillate as a washing water for floors or for equipment
– to use the distillate to produce new emulsions to be re-introduced into the working cycle.
The working cycle is very simple: it is necessary to apply a system of decantation and a de-oiler upstream to the Evaporator, to avoid the machine sucking in the larger sediments which are sometimes present, as well as any oil which has not been mixed in.
The pre-treated solution is then sucked in by the machine which in turn produces the distillate and concentrate.
Detailed case study, available only by request from our existing reps or contacts.
Please contact Georgina Porro: giorgina@cgdepur.it to inquire about this case study