Wastewater treatment solutions for different industries
Solutions for industrial local wastewater treatment plants
The selection of an industrial wastewater treatment method requires a thorough understanding of the characteristics of the wastewater to be cleaned. The designer of an industrial wastewater treatment plant needs to consider the customer’s requirements for the discharge location of treated wastewater based on the required water regulations. This selection depends on the analysis and use of the appropriate water treatment technology.
Wastewater generated in the pulp and paper industry contains significant amounts of organic and inorganic compounds derived from wood and the chemicals used in various manufacturing processes. Substances with high resistance to biological degradation (ex. lignin) and high toxicity (ex. resin acids) are problematic in pulp and paper wastewater treatment.
Commonly used sewage treatment practices include mechanical (sedimentation) and biological (aerobic aerated tanks with activated sludge) treatments which are assisted by chemical precipitation created by the introduction of reagent chemicals. This process can often introduce unknown toxic effects. Stronger environmental regulations force companies to search for new technologies and to improve existing methods to reduce pollutant discharge into water sources. One promising approach is the multi-stage technology where the first step is the physicochemical treatment of the most contaminated wastewater and the final stage is the biological treatment of combined wastewater. Among the physicochemical methods is the advanced oxidation processes (AOP) with the use of ozone, ozone and UV radiation, H2O2 and O3. All three processes simultaneously are very promising in treating the initial stream of wastewater.
The leather industry produces large quantities of organic matter-containing wastewater (including fats and proteins) and mineral substances (including the toxic compounds chromium and sulfides). Initially, mechanical treatment such as waste screening, FOG (fats, oils, grease) removal and solids’ sedimentation is required. Next is physical-chemical treatment including oxidation of sulfides, chromium precipitation, removal of both COD (chemical oxygen demand) and suspended solids by coagulation and flocculation.
For the textile industry, wastewater treatment uses adsorption on active carbon, chemical oxidation, ultrafiltration, nanofiltration and ion exchange. These methods can be combined with a multi-step cleaning system which can achieve several times the rate reduction of waste compared to the yield achieved when each process is used separately. The disadvantage of these technologies is the high energy consumption which is why technical solutions are being developed which would reduce both investment and operating costs.
Esmil equipment application in this solution:
- Screens and fine screens (Rake bar screen, Step screen, Hook screen, Drum screen, Drum screen brush, Screw screen)
- Grit separation and treatment (Tangential grit chamber, Combined mechanical treatment module, Chain scraper for horizontal-flow grit chamber, Penstock)
- Grinder screens and waste grinder
- Screw conveyor
- Screw compacting press
- Clarifiers equipment (Radial scraper, Radial suction scraper, Chain scrapers for horizontal-flow clarifier, Picket stirrer, Trays and weirs)
- Flotation (DAF – Unit, Polymer solution preparation unit)
- Aeration system – tube air diffusers
- Sludge dewatering (Belt thickener, Belt filter press, Multi-disc screw press dehydrator, JD dehydrator, Chamber-membrane filter press)