Concept of Integrated Technologies in Wastewater Treatment
Dr. Nivedita Sahu
Sr. Scientist

CSIR-Indian Institute
of Chemical Technology, Hyderabad

S. Sridhar
Principal Scientist and Project leader
Membrane Separations Laboratory,
Chemical Engineering Division
CSIR-Indian Institute of Chemical
Technology, Hyderabad

This article deals with advanced technological solutions for the treatment of industrial wastewater. Wastewater from pharmaceutical, chemical and petrochemical industries as well as landfill leachates are specifically considered as representative of major problems encountered when treating industrial streams. The economic and environmental sustainability of the above solutions are also reported in this article.

Wastewater treatment processes are very important for environmental conservation. Increasing industrialisation and population in India has created huge potential in the area of wastewater management. Wastewater treatment market in India is still in the process of finding innovative technologies/solutions required for specific industry. The level and composition of pollutants varies for different industries. In many cases, industries are exploring applicability of processes for recovering specialty chemicals from their wastewater. These solutions have been fuelled by increasing need for conserving and reusing/ recycling water processes. Increased environmental awareness, public awareness and social responsibilities have raised the need to generate new wastewater treatment technologies with specific programs in this sector.

At the same juncture, most of the industries prefer system supplies capable of providing energy-efficient technology at competitive price/low cost. The equilibrium between low cost and efficient performance, limits the flexibility of the technical operation. Membrane Separation Laboratory at CSIR-IICT, Hyderabad has developed tailor-made processes for water treatment at low cost. The technology is highly efficient, effective and economical for treatment of wastewater from specific industries like Dairy, Kitchen, Pharma and Coffee. Dr. S. Sridhar, Principal Scientist and Project leader of this group says the integrated process with pre-treatment + Membrane Bioreactor (MBR) + Reverse Osmosis (RO) can meet Zero Liquid Discharge (ZLD) for wastewater treatment. Dr. Nivedita Sahu, Sr. Scientist from the group has developed unique microbial cultures for treating many of these effluents by breaking down the Chemical Oxygen Demand (COD). With her background on phycology, she plans to carryout algal-based phycoremediation to enhance treatment efficiency and improve percentage water recovery.

Dr. Sridhar adds that in present scenario, it is also necessary to provide value addition to reduce the total cost of operations while fulfilling the existing criteria. The group, at IICT has successfully commissioned membrane based pilot plants of 7,500 L/day to 1.10 lakh L/day for processing effluents from acrylic fiber industry, pharmaceutical producers and steel manufacturers to recover valuable solvents and water. The technology developed at Membrane Separation Laboratory, CSIR-IICT is a novel membrane based integrated process that combines chemical coagulation, microbial degradation, membrane separation and if necessary, post treatment by UV, ozonation or activated carbon. MBR is a device which combines microbial action with membrane separation to eliminate secondary clarifier and achieve process intensification. MBRs can be operated in aerobic and anaerobic mode depending upon effluent characteristics, with the latter involving simultaneous generation of energy in the form of biogas apart from facilitating water reclamation. Usually MBR is incorporated with MF or UF membranes to clarify and disinfect the water and make it fit for reuse or utilization in irrigation. If higher water purity is desired, MBR can be combined with RO. Unlike, MBR, in moving bed bioreactor (MBBR) configuration, the entire mixed liquor suspended solids (MLSS) need not be recirculated through the membrane assembly and only the overflow water from reactor is processed by microfiltration (MF) or ultrafiltration (UF) before reclamation. MBBR could be useful for effluents which are less biodegradable and need aeration or activated process.

Figure 1: Membrane Filtration Integrated Process

The possibility of using MBR integrated with RO can be considered an effective and easy process for the de-colorization and de-odorization of these waste streams. The process is safe, rapid and does not generate any pollutants. The graphical sketch shows the types of approaches adopted during treatment.

Impact of Innovations in Wastewater Treatment

Dr. S. Sridhar feels that, the developments in the industrial wastewater sector in India are experiencing tough regulations. The presence of numerous industries and shift in wastewater treatment is towards the concept of ZLD has led to process and system design with equipment such as MBR, RO, UF, NF with chemical treatment/ pre-treatment. Membrane based integrated processes provide better solution for ETPs and STPs. The key benefits are: (a) ease and safety of handling equipment, (b) effective removal of recalcitrant components, (c) efficiency in selective applications like recovery of specialty chemicals for specific needs in industries, (e) equitable water distribution and utilization, and (f) economy. The industries get benefited by adopting hybrid/integrated technologies with chemical treatment/ pretreatment+MBR+RO, Zero Liquid Discharge (ZLD), etc for wastewater reuse.

Key Challenges

Industry's acceptance to adopt new technology is a key challenge for technology providers.

Future Scope

Water scarcity is a global issue/concern. Conventional technologies for treatments are well proven but more technologies with less energy consuming based on 3E's concept ("efficient, effective and economy") need to be showcased. MBR + RO/UF/NF and MBBR + RO/UF/NF are such technologies which are finding prominence in wastewater treatment. The adoption of these technologies in the industrial sector will define enhance scope for effective and economical treatment of wastewater to achieve ZLD and conserve water.