Chemical industrial wastewaters contains organic and inorganic matter in varying concentrations. Many materials in this industry are toxic, and almost non-biodegradable. Therefore the wastewater produced in this industry is not very easy to treat. For instance, surfactant and petroleum hydrocarbons, among others chemical products that are being used in chemical industry reduces performance efficiency of many treatment unit operations. Several processes can be used in different treatment schemes for chemical effluent. In general there are three different stages of treatment:-
1. Primary treatment / Physio-chemical treatment
a. In chemical industry oil & grease, solventare present in substantial quantity. To remove it we can use processes like, API oil separator, TPI, and, DAF. Suspended solids (TSS) and toxic chemicals like chromium, copper, lead, mercury, etc. are removed by sedimentation, coagulation, flocculation processes.
b. Recommended process: – HRSCC/Primary sedimentation and Dissolved air flotation (DAF)
2. Secondary treatment / Biological treatment
a. The secondary treatment is carried out by microorganisms under aerobic or anaerobic conditions and involves the reduction of BOD, COD and nutrients present in the water. These chemical affects the growth of microorganism that directly impacts the efficiency.
b. Recommended process: – Membrane bioreactor (MBR) uses a combination of the activated sludge process with an additional membrane separation process. It can treat high strength organic wastes.
3. Tertiary treatment
a. The tertiary treatment involves the use of filtration process, ultrafiltration (UF), reverse osmosis (RO) and ion exchange to remove the final contaminants in the wastewater. Membrane fouling occurs frequently while treatment due to the presence of toxic chemicals in the effluent.
b. Recommended process: -Ultrafiltration (UF) (If MBR is not in the treatment scheme) and Reverse osmosis (RO)
4. Zero liquid discharge
a. Evaporator (PFET), Distiller (PFMED) and Crystallizer (MEE) are used further to treat the reject of tertiary treatment.
b. Recommended process: – Polymeric film evaporation technology (PFET) and Multi effect evaporator (MEE)
At the end of all these processes we are able to get approximately 90% of pure water from the effluent fed. Arvind Envisol has a vast experience and installation base in the textile industry and a thorough knowledge of its various manufacturing processes and also its requirement for uninterrupted water supply.