Research and Development
Innovative. Functional. Sustainable.
We utilize knowledge, technologies and innovations in industrial production and sustainable waste stream management.
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The knowledge and experience of CROTEH’s employees and partners provide for the development and application of sustainable technologies that ensure the much-needed reduction of the burden on the environment.

  1. Our own reactors for conducting anaerobic and aerobic biological treatment tests (UASB, SDR, SBR, aerobic-anoxic reactor, reactor for thermo-chemical hydrolysis of substrates)
  2. Testing and development of effective technologies for anaerobic waste and wastewater treatment 
  3. Implementation of anaerobic and aerobic biological waste treatment simulation processes
  4. Research projects in the field of new technologies (raw materials for biogas production, biorefineries, circular economy, etc.)



Optimization of waste recovery operations based on biodegradability testing

1. The process of waste treatment, as one of the most significant issues in the area of environmental protection in the Republic of Croatia, primarily aims at material and energy utilization of waste by replacing waste with other materials (primarily raw materials).

2. The determination of the share of biodegradable waste is an important starting point for further waste handling.

3. Certain procedures are exclusively waste-to-energy directed. Biological waste processing technologies enable the material utilization of the remaining nutrients in the form of compost, as well as energy use through the utilization of the produced biogas.

4. In its work, CROTEH prefers an integral approach to organic waste management and treatment by selecting the most appropriate method of pretreatment/sorting, defining biodegradable waste treatment technology, and drafting the necessary documentation.


Development and optimisation of anaerobic digestion and co-digestion of organic substrates

1.  Anaerobic digestion is the optimal process for the stabilisation of organic waste materials with a high water content that produces biogas that belongs to renewable energy sources. In conventional biogas plants, the most commonly used substrates are various livestock slurries (except poultry) combined with corn silage. Given the rising trend of corn silage prices, grass silages, as well as organic residues from food, pharmaceutical, chemical, leather and paper industries and other similar industries, can be used as a quality substitute for corn silage.

2. For our clients we develop co-digestion or mono-digestion processes of new or replacement substrates that are often not readily degradable and can also inhibit microorganisms and the entire process of biogas production.

3. The manner in which the process needs to be adjusted and/or to what extent and with which procedures the substrates need to be pretreated in order to fully and without inhibition provide for the production of the maximum possible amount of biogas through the anaerobic process is determined during the development.

4. One of the development goals includes a partial/complete replacement of unsustainable (expensive) substrates with more available and cheaper ones in order to reduce waste disposal costs in the manufacturing industry and increase revenues from their processing at biogas plants.


Development and optimisation of industrial wastewater treatment processes

1. Testing the industrial wastewater load is primarily necessary given their higher organic load rate than when compared to municipal water.

2. By using equipment and reactors with granulated biomass on a pilot scale (UASB reactor), we test continuous wastewater treatment processes and determine all key parameters for achieving optimal treatment and process conditions.

3. The application of anaerobic digestion on industrial wastewater with organic load has proven to be very cost-effective, usually with an investment return period of 2 to 5 years. The possibility of direct utilisation of the produced energy for one’s own production process, as well as a high degree of thermal energy utilisation, do represent an additional reason.

4. In cooperation with our international partners, we develop custom-made wastewater treatment processes for our clients in the region. In addition to applying anaerobic technology, also used as needed are other physicochemical and biological treatment procedures that are being applied at industrial plants in the region.

5. We base our approach on ensuring optimal wastewater treatment in order to comply with legal limit values and provide for economic and ecological system sustainability.


Development and optimisation of municipal wastewater treatment processes

1. Municipal wastewater or already anaerobically treated industrial wastewater with no significant organic load is mostly treated by aerobic processes or a combination of anoxic-aerobic processes.

2. Our aerobic-anoxic reactor enables us to test the wastewater treatment process as well as the removal of nitrogen and other compounds under different conditions while complying with the legal limit values of wastewater emissions.

3. Based on the test results of the purification process and wastewater key parameter analyses, we develop and optimize existing municipal wastewater treatment devices for our clients (especially in cases of increased load), and provide technical assistance for operating the device.

4. Acting in the area of municipal wastewater treatment and in cooperation with our partners, we offer a complete range of services from testing organic load and other physicochemical parameters, analyzing possible purification options, defining the optimum wastewater treatment technology, and preparing all types of projects and technical documentation.


Development of processes for the treatment, reduction and disposal of sludge

1. Every wastewater treatment device produces sludge. When using anaerobic wastewater treatment technologies, the sludge increase ranges from 3 to 10% of the removed load, as opposed to using aerobic treatment processes, where the increase in sludge can be up to 60% of the removed load.

2. Most sludge is considered waste; however, certain sludge types can be reused commercially. Since the ultimate sludge disposal costs are extremely high, ways of reducing the amounts of sludge remaining after treatment are sought.

3. The amount of sludge can be reduced by classic “end of pipe” procedures, such as, for example, anaerobic digestion, aerobic digestion (auto thermal), oxidation, etc. It is also possible to apply integrated procedures for that purpose, such as ozonation, cavitation, etc., where the wastewater treatment process includes sludge treatment.

4. CROTEH develops and designs optimal sludge treatment procedures, primarily taking into account the impact on the environment, that is, the economic component of the treatment process itself and the ultimate disposal of sludge.


Difficult-to-degrade lignocellulosic material testing

1. Difficult-to-degrade lignocellulosic materials are rich in organic substances; however, these are found within materials as complex organic compounds, such as lignin, cellulose, or hemicellulose, and the biological decomposition of such compounds is much more difficult.

2. The research focused on the treatment of difficult-to-degrade lignocellulosic materials aims to identify and determine the necessary and most significant process parameters and to develop an anaerobic digestion process enabling the maximum utilization of the processed substrate.

3. The maximum utilization of the energy potential of the processed substrate during treatment of not-readily degradable materials is achieved by determining the optimal process parameters, such as substrate pretreatment method and conditions; temperature; pH; retention time; optimal co-substrate ratios; mass and energy transfer method; and the selection of appropriate treatment technology.

4. The CROTEH team specializes in the development of biogas production technologies from hard-to-degrade lignocellulosic materials by implementing a project financed by European Structural Funds. After the technology has been successfully developed on a laboratory scale, a further goal is a process “scale-up”, that is, the development of the process on an industrial scale and the evaluation of its economic viability.