ISSN 2320-5407 International Journal of Advanced Research (2016), Volume 4, Issue 7, 2196-2200 2196 Journal homepage: http://www.journalijar.com INTERNATIONAL JOURNAL Journal DOI: 10.21474/IJAR01 OF ADVANCED RESEARCH RESEARCH ARTICLE Experimental studies on lactose biodegradation of dairy effluent by K.lactis. * Sumithra 1 , AVN Swamy 2 and VV Basava Rao 3 . 1. Department of Biotechnology, CBIT Gandipet, Hyderabad. 2. Department of Biotechnology, CBIT Gandipet, Hyderabad. 3. Department of Chemical Engineering, OUCT, Osmania University, Hyderabad. Manuscript Info Abstract Manuscript History: Received: 12 May 2016 Final Accepted: 19 June 2016 Published Online: July 2016 Key words: Biodegradation, COD, Dairy effluent, Lactose,batch and continuous process. *Corresponding Author Sumithra. It is inevitable to treat the dairy waste effluents since they are the most polluting ones due to its huge volumes discharged to the inland surface water streams.The COD range of the dairy effluents is about 2000-3000 mg/L. About ten organisms of different species have been tried for finding out their ability to degrade lactose. Among the ten organisms tested three strains were found to be most promising namely K. lactis, C. laurentii and L. plantarum. The strain K. lactis,degraded all the lactose during exponential cell growth phase and removed 67% COD in shake flask cultivation.Based on the above results, a batch and continuous process was performed with K. lactis to the optimize and scale up of the biodegradation process.The present studies are carried out to evaluate the performance of various microorganisms in degrading lactose present in dairy effluent and the highly degrading strain of K.lactis was identified. Copy Right, IJAR, 2016,. All rights reserved. Introduction:- The dairy industry revolves around the processing of raw milk to different products (e.g. yogurt, cheese, cream, milk, etc) [1] (Rivas et.al20100 .Its processing discharges vast amount of effluents which may result in severe pollution of environment. According to Carvalho et al. the water consumption, depending on production, is between 1-4times that of milk received [2] .Dairy wastes, due to their composition, volumes and fluctuating flow rates, represent a problem for municipal wastewater treatment plants therefore, treatment of this kind of effluent seems to be essential [3] .Several pretreatment technologies have been developed and applied to treat dairy effluent such as activated sludge system, anaerobic pond, oxidation pond, trickling filter, and combined trickling filter/activated sludge system [4] (Garrido et al., 2001; Perle et al., 1995). Pretreated effluent from these processes have considerable amount of biological and chemical oxygen demand (BOD & COD), oil and grease and also some other pollutants. The pollution load is linked to the wastes organic content which is typically measured as COD and BOD [5] .Cheese whey, a dairy industry by-product [6] , stands out with a COD significantly greater than the other effluents. In order to eliminate these pollutants, conventional biological treatments of aerobic and anaerobic treatments or facultative digestion are the most commonly used. Materials& methods:- Milk industry wastewater:- The waste used is the permeate from Effluent treatment plant. It was obtained from Vijaya Dairy in Hyderabad. The wastewter was stored in sterile containers in a fridge or a cooling room at 4 o C and used within a week. Microbial strains:- A total of 10 strains were tested for their ability to degrade lactose. Cryptococcus laurentii CY-0301, Cryptococcus flavus CY-0901, Kluyveromyceslactisvar. Lactis ky-0603, Kluyveromycesmarxianusky-0403, Lactococcus Lactissubsp. Cremoris HP and Lactobacillus Plantarumsubsp. plantarumLp 39 were ordered from the Leibniz instituteDSMZ (German collection of microorganisms and cell cultures). In addition, strains of