An analytic report on how to manage industrial Wastewater highlighting some of the advanced wastewater treatment technologies and products
India has seen rapid growth of industries over last two to three decades. Along with economic development India also has to contend with air pollution and water pollution. For many years industries have been dumping liquid as well as solid waste in lakes, rivers and open fields. The cumulative effect in terms of increasing unfertile land, water related diseases, scarcity of drinking water, loss of aquatic life, etc can be felt.
Continual rapid expansion of cities has not only increased the demand for land but also demands fresh water supply. Approximately 70 to 80 per cent of fresh water used during the day gets generated into domestic sewage (municipal sewage). This sewage that passes through sewer lines, drainage lines, nallahs, canals etc is treated in Sewage Treatment Plant (STP) before being discharged into immediate environment.
Over the past few years concern for the environment in India has been growing. This is due to stringent execution of laws and procedures by pollution control authorities. “People have realised the need and benefit of treating or recycling wastewater, even if most industries have their own ETP for wastewater, it always gets the last priority on all fronts,” states Ajit Joshi, Manager – Analytical Division, Forbes Marshall Pvt Ltd.
Various chemical and biological treatment applications have been designed and implemented in sewage treatment plants. In India, on one hand where an average value of wastewater generated is 35000 MLD only 11000 MLD is treated whereas on the other hand out of approx 269 major STPs only 231 have been in operations. Hence the operational gap during the treatment have created challenging situation for treatment technologies.
One of the pioneers in the field of bioremediation, Organica Biotech is treating billions of litres of sewage globally. Sagar Dumbre, Technical Manager, Organica Biotech Pvt Ltd says, “Apart from day-to-day treatment of COD, BOD, ammoniacal nitrogen, odour, colour etc, today’s sewage treatment plants are facing more challenging concerns like heavy electricity consumption, high sludge generation. Through everyday’s extensive R&D activities, Organica Biotech thrives to resolve such concerns.”
Biological treatment system has always been the most preferred way of treating the wastewater. Dumbre says, “Without the effective microbial technology no biological system can function at its maximum efficiency. No matter whatever size, whichever technology we apply, if we do not have the right consortium of microbes at the right time and right place, it will not only affect the overall efficiency of the plant but will also increase the overheads to operate the sewage treatment plant.”
During the actual operation of the effluent treatment process, industry depends on offline measurement of different parameters. One can definitely save on the cost of online instruments, however by losing much more in terms of inconsistent control over process parameters. With the help of offline analysis, which is done only once or twice a day, one may not know the fluctuations taking place in different control parameters such as pH/TSS/MLSS/DO/COD/BOD etc. If a person is not aware of exact effluent load, the person will never attend to stabilised control over effluent treatment.
Manoj Ahire, Territory Sales Manager, Thomas-Gardener Denver Engineered Products India Pvt Ltd says, “With manufacturing and R&D facilities in USA, Germany and China and global sales and distribution network, Thomas has the unique edge of integrating the state-of-the-art pump technology into your desired application.”
“A complete effluent treatment process is designed to treat all pollutants present in effluent. It is important to know the quality of the final effluent, which is discharged from the plant. Typical parameters, which can be monitored, are pH/ turbidity/ DO/ MLSS/ redox/ suspended solids/ COD/ BOD/ TOC,” says Joshi. Following are few advanced technologies and products to manage industrial wastewater:
  Sewage Aeration – Thomas pumps are used in different types of systems that are used today to control wastewater in residential homes. Wastewater from the household enters a compartment where air is introduced to begin the growth of aerobic organisms. The organisms convert the waste organic materials into gases and additional microbial cell material. In addition to supplying oxygen, the aeration system keeps the contents of the aeration zone well mixed to provide optimum exposure of the micro organisms to the waste materials. Effluent may be discharged to a ditch or to a new or existing drain field, whichever is mandated by local health restrictions.
   Pond Aeration – Thomas compressor is used to pump air via a diffuser into a pond or lake. Pumping air bubbles into a pond or lake increases the oxygen concentration of the water thus preventing the water becoming stagnant. Aeration is used also to provide suitable living conditions for fish and other aquatic species in places otherwise lacking in sufficient oxygen.
 ORP      – Oxidation-reduction potential, commonly known as ORP or redox, is a millivolt measurement which indicates the tendency of a chemical species to lose or gain electrons. Oxidation refers to a loss of electrons, while reduction refers to a gain of electrons.
Nitrification is a biological process that involves the oxidation of ammonia to nitrate by nitrifying bacteria. In wastewater treatment, nitrification occurs under aerobic conditions which require a dissolved oxygen level between 1and 3 mg/L.
Denitrification is a further biological process that may be performed in wastewater treatment plants; it involves the reduction of nitrate into molecular nitrogen.
“Denitrification occurs under anoxic conditions, which have a very low dissolved oxygen level, typically less than 0.5 mg/L. Anoxic conditions allow denitrifying bacteria to thrive and break down nitrate as a source of energy in the absence of oxygen, as seen in the following equation: 6NO3-+ 5CH3OH  5CO2+ 3N2+ 7H2O + 6OH-,” informs Kondiba Metkari, Business Manager, Hanna Equipments (India) Pvt Ltd.
Traditionally, wastewater operators’ use dissolved oxygen readings to control the nitrification and denitrification processes, creating aerobic conditions for nitrification followed by anoxic conditions for denitrification. However, since dissolved oxygen levels can vary with depth and location, ORP readings can be used to more accurately monitor these biological processes. ORP readings between +100 and +350 mV indicate the presence of oxygen and nitrate, showing that nitrification is effectively taking place. ORP readings between -50 and +50 mV indicate anoxic conditions and utilisation of nitrate as an energy source by microbes, ensuring effective denitrification.
 BioSens – BioSens uses biosensors to monitor BOD value of any sample. It requires very little manual intervention with minimal running cost.
“BioSens has the most modern features with web connectivity. Mainly users can dispense with BOD incubators, hazardous chemicals and the waiting period of 3 days,” says Joshi.
 Low electricity consumption – Sewage wastewater majorly comprises of complex organic mixtures that needs to be treated before discharging into the environment. The most conventional treatment method i.e. Activated Sludge Process, requires oxygen in the biological reactors which is provided through massive air blowers. The excess dissolved oxygen provided (more than 2.5 ppm) in the aeration tank is further contributing to the rise in the electrical cost. Continuous operation of blowers has not only attracted operational challenges but significantly increases the treatment cost as well.
Organica Biotech has isolated and developed consortium of microbes that are able to sustain and degrade sewage in low dissolved oxygen levels (1.5 – 2 ppm) without affecting the efficiency of the plant. Alternatively speaking generally, oxygen requirement is 1.5 – 2 kg of O2 per kg of BOD. With the usage of its microbes the oxygen requirement can be reduced to as low as 1 kg of O2 per kg of BOD. This can result in 33 to 50 per cent of energy reduction. These microbes have proven to reduce the organics under low dissolved oxygen conditions. The right microbes optimally utilised the diffused air. This has helped various sewage treatment plant managers to treat maximum sewage in lesser treatment period.
 Maximum sludge reduction- Inefficient treatment, poor biomass and incomplete digestion lead to high volume of sludge generation. Disposing of excessive sludge has become a nuisance and thereby has increased the operational and maintenance cost of sewage treatment. Organica Biotech has identified consortium of microbes that can degrade excessive volume of sludge. These microbes release substrate specific enzymes that break down the complex organic substances into simpler form. The simpler organics are then maximally degraded by the microbes for their growth and development. This results in generation of lower volume of sludge.