Waste Water

The world challenge is today the way of managing the waste waters:
• How to collect them
• How to treat them
• How to discharge them.

Water recovery is an essential part of environmental management and minimizes the consumption of water resources. The utmost aim is to reduce the production of waste waters, optimizing the majority of the processes at the maximum extent.
Once the waste water is an unavoidable residual, then the effort should be focused on the application of the best technology to be applied for the specific case, planning the three phases of collection, treatment and discharging with the same attention to environment, to the operability, to the investment.
As an EP contractor present in the world market, Gemwater is actively involved in finding always new solutions. Gemwater’s challenge is to apply the more up-to-date technologies and the more reliable solution to each industrial case.

There are many processes for wastewater treatment. They include physical, biological and chemical treatment. Sludge treatment has mainly the purpose to reduce the volume of wastes to disposal or reuse and to produce environmentally safe fluid waste stream. Gemwater applies a wide variety of technologies for waste water treatment and water recovery:

Extraction of oil from reservoir wells is always accompanied by a production of water, called “Produced Water”, which is usually a mix of formation and connate water (which are the water naturally present in the reservoir), as well injection water which can be previously injected in the oil wells.
Produced water is usually a salty water normally containing:
• Dissolved Gases (Hydrocarbon, Carbon Dioxide, Hydrogen Sulfide, Ammonia)
• Oil & grease
• Suspended solids

Over time, as the reservoir tend to depletion, the  quantity of produced water increases. Therefore, treatment of the water to comply with specification for injection as well as with legislation for disposal, is recognized a key aspects of the oil business.
Many key aspects shall be evaluated in the selection of the proper treatment technology, like:
• Water flow rate and variability in flow oil concentration solids etc.
• Water quality in (from wells, separators): oil droplet & solids particle concentration and size distribution,
  production chemicals
• Water quality out (specification for discharge PWRI)
• Weight and footprint, operability, redundancy, expandility, etc.

There are a wide range of physical processes for produced water treatment. Main tasks of the produced water treatment processes for water injection and disposal are the removal of oil and suspended solids. In case of treatment for water reuse (industrial and agricultural), the task is the removal of salts, organics, silica and colloidal by means of Thermal Evaporation.

Some of the technologies to be applied to this type of process are listed to follow:


Sludge treatment has mainly the purpose to reduce the volume of wastes to disposal or reuse and to produce environmentally safe fluid waste stream.
Suspended solids can be originated from primary water treatment (grit removal, equalization basins, clarifiers, etc.), biological/chemical process, wastewater treatment plant (filtration, etc.).

Sludge treatment includes physical, chemical and biological processes, or a mixture of these above.

Some of the technologies to be applied to this type of process are listed to follow:

Wet Air Oxidation is a thermal treatment process. The wet oxidation operates oxidizing dissolved or suspended components in water using oxygen or other oxidizers. In case the oxidizing component is air, it is named Wet Air Oxidation.  
Temperatures and pressures are severe: water is superheated, pressure ranges from 10 to more than 200 bar.
The oxidation is very efficient in process involving liquid organic waste streams, too diluted for incineration and too concentrated for biological treatment.
Another valuable characteristic is the volume reduction and sterilization of organic sludge.

Gemwater WAO process is unique, because the reactor system is configured to promote a high degree of liquid mixing, as a perfectly stirred reactor. The result is maximum oxygen transfer from air into the liquid medium, producing improved oxidation performance at less severe operating conditions.
The oxidation proceeds according to a chain reaction mechanism described below:

Acid acetic plays an important role  in completing the extent of oxidation. It needs the most extreme condition to oxidize to carbon dioxide. By increasing the temperature, the extent of oxidation is more than 90%.

WAO has a wide range of applications. The principal are listed to follow:
• Spent caustic streams from refineries
• Ethylene production (Steam Cracking of Paraffinic Hydrocarbons)
• Gas production processes, especially during sulfur recovery units
• Soot slurry downstream hydrocracking and gasification process (syngas), in order to reduce the amount of
  wastewater solids requiring off-site disposal
• Petrochemical plants producing polyolefins, caprolactam, methyl methacrylate (MMA), melamine and other
  organic and inorganic chemicals.

In sewage sludge from industry or municipalities WAO is a very efficient application major cities or Industrial complexes are facing today a common challenge dealing with sludge disposal. New treatments have to be sustainable, meaning a minimal impact on environment and a recycling of both energy and materials. GEMWATER Wet Air Oxidation is the process to treat sludge through the thermal oxidation of the bio-solid residual in the liquid phase.  
This application has several environmental plus as it reduces the overall quantity of suspended solids, provides an efficient disinfection reducing the problem and costs connected with further handling of the product. Another important aspect is the improvement in dewatering, because reducing the quantity in dewatered sludge, the operating cost of the plant are significantly reduced.
Aside the main purpose of treating the sludge, as an oxidation process, it is an exothermal reaction (combustion), so it can be exploited also to generate energy. 

A typical WAO run continuously. Comparing this process with the normal incineration, in WAO the quantity of waste gas is about one tenth.
Air Injection Location GEMWATER injects 90% of process air into the reactors
Heat Exchanger Orientation GEMWATER uses tube type mounted horizontally to facilitate easy maintenance
  and tube bundle extraction.
Pressure Let-down GEMWATER system separates the liquid/vapor stream prior to dropping the pressure
Reactor System  GEMWATER reactor system is a CSTR type
Nowadays the problem of the volume of wastewater that requires treatment, is becoming more and more one of the main issues toward the public perception of industrial impact on the environment.
Thanks to the integration of qualified personnel to the existing structure and the aquisition of a dedicated company, Gemwater is able to design and build the technical solution in order to MINIMISE the liquid discharge and the environmental impact, following any type of Standard requirement from Customer or End Users.
Zero Liquid Discharge (ZLD) describes a process that tends to completely eliminate liquid discharge from a system. The goal is to minimize process wastewater in an economically feasible manner. The other aim is to produce the clean streams suitable for reuse elsewhere in the facility.  

The ZLD treatment can be thermal and/ or non-thermal systems. Here to follow some of the technologies that Gemwater provides in Zero Liquid Discharge application.