Cavitations technology
The recent merger between DEWACO LTD and Cavia Technology of Finland, a company specialised in ultrasonic treatment systems enables DEWACO LTD to include “cavitations technology” to its portfolio to consolidate in this competitive high-potential sector. Disruption of sludge cells by means of DEWACO LTD “high frequency” ultrasonic cavitations treatment enables the release of light organic substances into the sludge water thereby exposing them for further anaerobic digestion. In practical terms, a certain portion of the biological sludge will be treated using DEWACO LTD ultrasonic cavitations treatment prior to digestion. This process encourages the exploitation of valuable materials and energy from stabilised sewage sludge just before its final disposal. In addition, DEWACO LTD ultrasonic treatment can be utilised to improve dewatering efficiencies of biological sludge.
Your advantages at a glance: (Overall benefits)
 Improved biogas yield, as high as 40%
Reduced sludge quantity, approx. 25%
Can be used to retrofit to existing digesters
Overall digesting capacity can be increased
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Improved total solids content of sludge
Considerably reduced polyelectrolyte consumption
Reduced disposal costs
Minor investment cost
Basic process:
 Approximately 30% of the biological sludge will be treated inside the specially designed cavitations chamber in continuous flow basis prior to digestion. After this particular treatment, the treated sludge will be fed into main stream. Neither the primary sludge nor the remaining biological sludge will be treated. Results showed that subsequent anaerobic digestion of the ultrasonically disrupted sludge, could improve biogas production with reduced sludge quantity that is vital to the economic consideration of the wastewater treatment plants.
Equipment and technology:
The core instrument of this technology is the cavitations chamber, a series of tubular modules where 30% of biological the sludge flows through. Nominal power rating of the cavitations is approx. 4,8kW/module.
During ultrasonic treatment, high frequency acoustic signals are used to initiate the cavitations process. The applied ultrasonic field leads to a breakdown of cohesive forces of the liquid molecules resulting in the generation of cavitations bubbles. Disruption of sludge cells enables the release of light organic substances into the sludge water, thereby exposing them to further anaerobic digestion.
To obtain optimum treatment efficiency, it is necessary to keep the d.s. range at a level of approx. 4%. Practically, this is done using either existing thickening equipment, or the technology that is available within scope of DEWACO LTD.
Useful parameters:
Below is a list of useful parameters that need to be considered while selecting and sizing the equipment:
- Not more than 30% of biological which is fed into the digester will be treated through ultrasonic cavitations.
- The volume of tubular modules has to be big enough to allow approx. one minute of retention time.
- It is necessary to keep the d.s. range at a level of approx. 4%.
DEWACO LTD engineers will help you study your requirements, and decide from a selection of the most suitable system and equipment, suited to your requirements on the most economical terms.
Operation / test runs:
Upon completion of installation and connection onto the process, DEWACO LTD experts will assist you to carry out test runs and do adjustments / modifications necessary to obtain an optimum outputs. Generally, the entire system functions automatically, and continuous attention of the operator is not required. An in-built process database (software) will register/monitor all operational parameters into its memory, and react immediately should any defect arise. In an emergency situation, all alarms can be transferred to a desired GSM number via a modem. Moreover, in-built software will continuously indicate necessary maintenances, to be performed by the operator.
Measures to be taken by the customer:
In order to substantiate the entire cavitations process, the plant should uphold:
- Recodes of the gas yield
- Functional and reliable monitoring of the gas
- Recodes of final residuals
- Functional and reliable monitoring of final residuals
- Recodes of the dewatering performances
- Functional and reliable method of dewatering performances
Above listed measures are the practical preconditions that are required, in the event the customer acquires boosting of digestion as a service, whereupon a significant amount of invoicing will be proportional to gas yields monitored at the plant.
It is the customer’s obligation to carry out all necessary modifications required to install the equipment package.
Instrumentation/acquiring the services:
DEWACO LTD offers the following options for boosting of the digestion process:
- As a service package, DEWACO LTD with its local partner will carry out sizing, designing, installation, service and maintenances of the entire cavitations equipment. During the installation, DEWACO LTD has the capability to provide comprehensive training for the operators according to their requirements. Each party should agree on their responsibilities and assignments as part of the contract.
Payments are generally split into two portions; basic installments, which is to be executed on a monthly basis and supplementary payments which will be proportional to gas yield profits. The preconditions for supplementary payments are; total gas yield, amount of final residuals and dewatering efficiencies. Monitoring will be carried out on a 3 – 6 month basis.
- As an equipment package, in which customer / end-user will acquire the necessary equipment from DEWACO LTD in one go, and carry out all other works by themselves. Acquiring of equipment will be in accordance with DEWACO LTD general terms and conditions.
Typical projection:
Below is a typical projection which illustrates sizing of the equipment package and benefits. These results are relatively comparable, as they were taken from various practical tests implemented recently.
Overview:
Attainable benefits:
An additional bio gas yield = free renewable energy = net profit
Decrease of final residuals = decrease of final disposal cost = saving
High dewatering efficiency = considerable saving in energy and disposal cost as well as polyelectrolyte
Equipment package / technology:
From one single supplier “flange to flange” concept, this includes all necessary components.
Useful parameters:
Not more than 30% of biological sludge will be treated
Solids consistency range 4%
Customer inputs:
- As a service package
- As an equipment package
We have real solutions for your bio gas production challenges.
DEWACO LTD cavitations system enable you to meet your requirements and increase output while reducing your total operational / investment costs.
DEWACO LTD team consists of highly qualified engineers, specialists and skilled technicians who will study your requirements, and help you decide from a selection of the most suitable cavitations system and equipment, suited to your requirements on the most economical terms.
If you have any questions, please contact us. We will answer your queries and assist you to opt for the right choice.
To obtain more information on DEWACO LTD products, please visit our website: www.dwteng.com
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