Microalgae for potential phycoremediation of Industrial effluent - A case study


V. Sivasubramanian

Director, Vivekananda Institute of Algal technology (VIAT)

R K M Vivekananda College, Chennai - 600004, India.

email  - vsivasubramanian@gmail.com





Microalgae are the most primitive and the first photosynthetic micro organisms to colonize earth. They are the primary producers in aquatic ecosystems and contribute to the oxygen levels in the atmosphere. Microalgae take up nutrients, evolve oxygen and effectively sequester CO2 Being simple organisms micro algae can adapt to any kind of extreme conditions. They can degrade a wide range of chemicals and remove most of the heavy metals. This ability of micro algae has found applications in dealing with pollution caused by industrial effluents. VIAT has been successfully implementing micro algae based technology to manage a variety of industrial effluents all over India for the past 10 years. These industries have been treating effluents in a conventional way which involves the use of chemicals at every stage of treatment process resulting in huge amount of sludge. Algae based technology avoids all these chemicals at the same time effectively bring down vital parameters to acceptable levels.




Phycoremediation is the process in which algae are employed to remediate environmental pollution. Olguin (2003) defines phycoremediation involves the use of macroalgae or microalgae for effective removal or biotransformation of pollutants, including nutrients and xenobiotics from wastewater and CO2 from waste air. Large-scale phycoremediation of industrial effluent has been done successfully in some industries in India (Sivasubramanian, 2006; Sivasubramanian et al., 2009; Sivasubramanian, 2010; Sivasubramanian et al., 2010; Hanumantha Rao et al., 2010). Using algae based treatment technology, efficient pH correction, sludge reduction and reduction of BOD and COD could be achieved by avoiding toxic chemicals by these industries. During effluent treatment process huge amount of valuable algal biomass is also being generated by these industries. 


1. World’s first phycoremediation plant at Ranipet, India

Large-scale phycoremediation plant is in operation at SNAP Natural and Alginate Products, Ranipet, India from September 2006. The industry generates 30 to 40 KL of highly acidic effluent every day which is being pH corrected and evaporated using algae based treatment technology developed by Sivasubramanian et al. (2009). There is 100% reduction in sludge by phycoremediation.

Phycoremediation plant at SNAP industries, Ranipet, India.


Phycoremediation plant is used to treat the acidic effluent from this alginate industry. The liquid effluent is highly acidic. Conventionally, sodium hydroxide has been used for the neutralization of the acidic effluent which results in an increase in total dissolved solids and the generation of solid waste. The study was conducted in three stages. In the first stage, the solar ponds used for evaporating the effluent were converted into high rate algal ponds with Chroococcus turgidus, a blue green alga. Based on the results of pilot plant studies, a full scaling up of the slope tank was made.


2. Phycovolatilization of heavy metals


Use of algae to treat industrial effluents containing heavy metals is an alternative to the biosorbents and physical and chemical methods. In this study, effluent from a leather-processing chemical industry in Ranipet, Tamil Nadu, India, was treated for the removal of heavy metals using the microalga, Chlorella vulgaris, which was isolated from the effluent itself. The results of the study showed that after 8 hours, C. vulgaris exhibited a better adsorption capacity under sunlight compared to laboratory conditions (i.e., 30.6 mg/g dry weight vs 10.5 mg/g dry weight, respectively). Similarly, reduction of heavy metals and mass balance in pilot-scale field studies conducted in a high-rate algal pond showed that the microalga, apart from adsorption, complexation, and entrapment mechanisms, is likely to possess phycovolatilization capability probably via biotransformation processes (Hanumantha Rao et al., 2010).


3. Effluent from confectionery industry


A Confectionery industry in Tamilnadu, India generates 50 – 70 kilo liters of effluent per day. The plant effluent generated is divided into two streams viz., industrial effluent stream from the production process and sewage effluent stream from the human activities.  These are mixed prior to sending to the equalization tank. The effluent for phycoremediation treatment is taken after it goes through the DAF(Dissolved air floatation) in the conventional treatment method. pH is conventionally corrected by adding caustic soda at the equalization tank stage which results in doubling of total dissolved solids (TDS). After pH correction the effluent is sent to buffer tank and anaerobic reactors (AR) to digest rest of the organic compounds. After digestion in AR effluent goes through a series of clarifiers and sand filter and finally taken to reverse osmosis (R/O)  for recycling.


Effluent Characteristics


The characteristic raw effluent produced by this confectionery industry is characterized by its organic content, which is composed of easily biodegradable compounds such as sugars, sweeteners, casein, vegetable oils, acacia gums, condensed milk, food coloring and flavoring agents, etc. This confectionery industry is using major ingredients such as sugar and sweeteners, natural colors, acacia gum, sugar substitutes, gum base and flavors for all type of confectionery products. They use number of chemicals during the process and they all become a part of the effluent. This liquid effluent is acidic in pH, dominated by yeast cell population.


Algal treatment


Chlorella vulgaris grows very well in the raw effluent.  It utilizes sugar present in the effluent. The effluent becomes less turbid and this reduces the load for the anaerobic reactors. Phycoremediation helps to correct pH, reduce sugar levels, reduces BOD and COD. Effluent is added and removed from the algal treatment tank @ 3500 L/h which is the flow rate requirement to anaerobic digesters. Algal biomass reaches to 1.5 g dry weight/L.


4. Effluent from soft drink manufacturing industry

Soft drink manufacturing units in India use ground water for the production. The ground water is filtered and softened using chemicals and sent to R/O and nano filtration (N/F) for further TDS reduction. The effluent generated by the industry includes R/O reject, reject from N/F, utilities, cleaning, softener regeneration, bottle wash and cleaning in process (CIP). In some units the treated effluent is sent to R/O for recycling. The effluent is treated with conventional chemical and physical methods. Removal of nutrients especially nitrates and phosphates are the major problem faced by this industry. The effluent contains high inorganic nutrients (nitrates and phosphates) and low pH. Microalgal technology is effectively employed to remove nitrates and phosphates. The effluent has all the essential nutrients for algal growth. Algae employed could remove nutrients (nitrate and phosphate) at a rapid rate well within the requirement of the industry.


5. Effluent from textile dyeing industries


Phycoremediation technology is employed in a few textile dyeing industries by the author and his team. Two textile dyeing industries were selected for the present discussion (one near Chennai and the second at Ahmedabad). In Chennai-industry the effluent is generated from various sources like dye bath, mercerizer, wash water, desizing water and printing. The industry generates around 200 KL of effluent per day. The effluent is treated with conventional physical and chemical methods resulting in huge amount of sludge and water effluent. The dyeing industrial effluents is rich in various dyes with high pH and TDS, because of various chemicals being used, like sodium bicarbonate, sodium chloride etc. The industry at Ahmedabad generates around 84,000 m3 effluents every day.  The effluent generated is highly alkaline and treated with conventional chemical methods.  Dye removal, reduction of BOD and COD are the major problems associated with effluent treatment. These effluents contain various dyes and high pH, TDS, BOD and COD because of various chemicals being used, like sodium bicarbonate, sodium chloride etc.


Phycoremediation of textile dyeing effluents


Effective color removal, pH correction, BOD and COD reduction and sludge reduction are achieved by algal treatment on both the industries. Effluent provides all the necessary nutrients for the algal growth. Cell number is maintained around 250 x 104/ml (0.75 g dry weight/L). In the Chennai unit the algal biomass is harvested, dried and used as fuel. The dried algal pellet has a high calorific value.



Phycoremediation of textile dyeing effluent and algal biomass production (a) Decolorization and degradation

of effluent before (left) and after (right) treatment with microalgae. (b) algal growth (c) dried algal cake


Algal biomass production in textile dyeing effluent


Both the effluents from the textile dyeing industry support very good growth of algae (Chlorococcum humicola).  The treated effluent after harvesting algal biomass is sent to R/O for recycling. The R/O reject is fed into phycoremediation plant as source of nutrients. The biomass generated was harvested and analyzed for assessing the quality. When compared to the control (lab grown biomass) effluent grown biomass exhibits higher values for most of the biochemicals. The FAME (faty acid methyl esters) analysis showed the existence of a single fatty acid in major composition indicating it is highly suitable for biodiesel production and a very little unsaturation is a good sign of hope in the process of biodiesel production from algae and the alga Chlorococcum humicola has a great potential of being a feed stock for biodiesel production.




VIAT has been implementing algae based technology to treat a wide range of effluents for the past 10 years. A few case studies have been summarized above to give readers an idea about the efficiency of phycoremediation and the benefits we can derive if the technology is developed and executed properly.  VIAT is right now involved in several projects in India and abroad. One of the major applications of algal technology is to treat acidic industrial effluents. Apart from this algal technology can be effectively employed to remove color, odour, COD, BOD and sludge from the effluents.


Integrating algal biomass production with phycoremediation seems to address most of the economics and problems associated with mass cultivation. Apart from cleaning the environment from the onslaught of ever increasing pollution, valuable and cheaper biomass is generated from wastewater, effluents and sludge if appropriate algal species are identified and grown in industrial wastes.




Hanumantha Rao, P., Ranjith Kumar, R., Subramanian, V. V. and Sivasubramanian, V. (2010) Environmental impact assessment of Chlorella vulgaris employed in phycoremediation of effluent from a leather-processing chemical industry. J. Algal Biomass Utln. 2: 42 – 50. 


Olguin, E. J. (2003) Phycoremediation: Key issues for cost-effective nutrient removal process. Biotechnol. Adv. 22: 81 - 91.


Sivasubramanian, V. (2006) Phycoremediation - Issues and Challenges. Indian Hydrobiology. 9 (1): 13 – 22. 


Sivasubramanian, V., Subramanian, V. V., Raghavan, B. G. and Ranjithkumar, R. (2009) Large scale phycoremediation of acidic effluent from an alginate industry. ScienceAsia 35: 220 – 226.


Sivasubramanian, V. (2010). Gaining an edge with algal technology. Search - The Industrial Sourcebook. 13 (3) : 6 - 80.


Sivasubramanian, V., Subramanian, V. V. and Muthukumaran, M. (2010). Bioremediation of chrome-sludge from an electroplating industry using the microalga Desmococcus olivaceus - a pilot study. J. Algal Biomass Utln. 1(3): 104  - 128.




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