Purnima Dhall

Biological Approach for the Treatment of Pulp and Paper Industry Effluent in Sequence Batch Reactor

Pulp and paper industrial effluent is rich in recalcitrant compounds and causes pollution. For the treatment of such compounds activated sludge process is frequently used in which F/M ratio is kept low. This treatment results in effective biochemical oxygen demand removal but other waste water parameters are not reduced effectively due to lack of dissolve oxygen. In the present study sequential batch reactor was used for the removal of pollutants from the waste water of pulp and paper mill by using bacterial consortium (Klebsiella sp., Alcaligens sp. and Cronobacter sp.). The aim of present research is to identify the influences of F/M ratio and dissolved oxygen concentration on the microorganism’s growth and pollutant removal. The process of bioremediation was optimized by Taguchi approach. Bioremediation experiment resulted in reduction of chemical and biochemical oxygen demand up to 72.3% and 91.1%, respectively. A significant reduction in colour (55%), adsorbable organic halides (45.4%), total dissolve solids (22%) and total suspended solids (86.7%) was also observed within 14hrs while, the sludge volume index was 52. The wastewater after the treatment process meets the standard given by regulatory agencies and can be discharged into the environment without any risks.

Biodegradation of sewage wastewater using autochthonous bacteria.

The performance of isolated designed consortia comprising Bacillus pumilus, Brevibacterium sp, and Pseudomonas aeruginosa for the treatment of sewage wastewater in terms of reduction in COD (chemical oxygen demand), BOD (biochemical oxygen demand) MLSS (mixed liquor suspended solids), and TSS (total suspended solids) was studied. Different parameters were optimized (inoculum size, agitation, and temperature) to achieve effective results in less period of time. The results obtained indicated that consortium in the ratio of 1 : 2 (effluent : biomass) at 200 rpm, 35°C is capable of effectively reducing the pollutional load of the sewage wastewaters, in terms of COD, BOD, TSS, and MLSS within the desired discharge limits, that is, 32 mg/L, 8 mg/L, 162 mg/L, and 190 mg/L. The use of such specific consortia can overcome the inefficiencies of the conventional biological treatment facilities currently operational in sewage treatment plants.

Bioremediation of Agro-Based Pulp Mill Effluent by Microbial Consortium Comprising Autochthonous Bacteria

Small-scale agro-based pulp and paper mills are characterized as highly polluting industries. These mills use Kraft pulping process for paper manufacturing due to which toxic lignified chemicals are released into the environment. Lack of infrastructure, technical manpower, and research and development facilities restricts these mills to recover these chemicals. Therefore, the chemical oxygen demand (COD) of the emanating stream is quite high. For solving the above problem, four bacteria were isolated from the premises of agro-based pulp and paper mill which were identified as species of Pseudomonas, Bacillus, Pannonibacter, and Ochrobacterum. These bacteria were found capable of reducing COD up to 85%–86.5% in case of back water and 65-66% in case of back water : black liquor (60 : 40), respectively, after acclimatization under optimized conditions (pH 6.8, temperature 35°C, and shaking 200 rpm) when the wastewater was supplemented with nitrogen and phosphorus as trace elements.

Validation of computationally predicted substrates for laccase

Present study reports the validation (oxidation) of computationally predicted oxidation of xenobiotic contaminants by commercially available pure laccase from Trametes versicolor. Selected contaminants were predicted as potential targets for laccase oxidation by using in-silico docking tool. The oxidation by laccase was measured by change in absorbance at specific λ max of each compound. Sinapic acid and tyrosine were taken as positive and negative controls, respectively. Oxidation was observed in m-chlorophenol, 2,4 di-chlorophenol, 2,4,6 tri-chlorophenol, captan, atrazine and thiodicarb, except malathion, which showed no activity. It could be speculated that the predicted substrates showing oxidation shared homology at structural and chemical level with positive control compounds. In case of malathion, structural non-homology with sinapic acid could be attributed to its inactivity towards laccase that required further structural analysis. Thus, a remediation tool proposing an advanced remediation approach combining the application of theoretical in-silico method and subsequent experimental validation using pure laccase could be proposed. As number and type of xenobiotics increase, the unfeasibility to screen them experimentally for bioremediation also rise. This approach would be useful to reduce the time and cost required in other screening methods.

Restructuring BOD:COD Ratio of Dairy Milk Industrial Wastewaters in BOD Analysis by Formulating a Specific Microbial Seed

BOD (Biochemical oxygen demand) is the pollution index of any water sample. One of the main factors influencing the estimation of BOD is the nature of microorganisms used as seeding material. In order to meet the variation in wastewater characteristics, one has to be specific in choosing the biological component that is the seeding material. The present study deals with the estimation of BOD of dairy wastewater using a specific microbial consortium and compares of the results with seeding material (BODSEED). Bacterial strains were isolated from 5 different sources and were screened by the conventional BOD method. The selected microbial seed comprises of Enterobacter sp., Pseudomonas sp. BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6. The ultimate BOD (UBOD) was also performed by exceeding the 3-day dilution BOD test. After 90 days, it has been observed that the ratio of BOD : COD increased in case of selected consortium 7 up to 0.91 in comparison to 0.74 by BODSEED. The results were analyzed statistically by t-test and it was observed that selected consortium was more significant than the BODSEED.

Biological AOX removal of pulp mill plant effluent by Pseudomonas Aeruginosa – Bench study

AbstractDischarge of adsorbable organic halides (AOX) into the water bodies has resulted into many health and environmental problems such as endocrine disruption, aquatic toxicity, bioaccumulation and carcinogenicity. The already known physical, chemical and electrochemical methods are not economically viable for the control of water pollution. So this paper focuses on the biological reduction of AOX from pulp and paper mill effluent using isolated bacteria. The isolated bacteria were screened and finally Pseudomonas aeruginosa strain 1 was used further. The effect of various parameters such as, bacterial cell concentration, surface washing of bacterial cell and agitation were investigated and it was found that to some extend every parameter has resulted in the reduction of AOX from the effluent. It was inferred that the three time washed pellet inoculated in the ratio of 1:1 (sample: pellet) and incubated at 150 rpm at 37°C for 24h has resulted in 78% of AOX removal.

Selection of an apt support for the immobilization of microbes for the development of a BOD biosensor

The present study entails the screening of different supports for the immobilization of a bacterial consortium for the development of a BOD biosensor. The supports used were PVA (polyvinyl alcohol) + nylon cloth, agarose, nitrocellulose and a nylon membrane. The stability of the prepared membranes was checked at regular time intervals in terms of their response with a reference standard, i.e. glucose–glutamic acid, while stored at different temperatures as well as at different pH values. It was observed that microbes immobilized on the nylon membrane exhibited a maximum stability compared to those immobilized on the other membranes. The study revealed that pH 7.0 was best suited for the storage of membranes harboring immobilized bacteria, preferably at 4 °C, with an observed stability of more than 400 days. Studies also showed that leaching was negligible in the case of a charged nylon membrane. The selected support material, i.e. the immobilized microbial nylon membrane, maintained its stability and activity after an intermittent use for 400 cycles.

BOD beads – a ready to use seeding material for estimation of organic load of wastewater

A reusable immobilized microbial composition is designed to estimate the biochemical oxygen demand in industrial wastewater streams. The formulated microbial composition comprises a synergistic mixture of the bacterial strains of Enterobacter cloacae (ATCC no. 29893), Citrobacter amalonaticus (ATCC no. 25406), Pseudomonas aeruginosa (ATCC no. 49622), Yersinia enterocolitica (ATCC no. 27739), Klebsiella oxytoca (ATCC no. 15764), Enterobacter sakazakii (ATCC no. 12868) and Serratia liquefaciens (ATCC no. 25641). The consortium is immobilized by using 2% sodium alginate and 0.15 M calcium chloride to form beads. The said beads are tested as a microbial seeding material for BOD analysis using glucose–glutamic Acid (GGA) as a reference standard. The obtained BOD values were comparable with the values obtained by using sewage as the seeding material. Simultaneously the beads were tested on several synthetic samples as well as industrial effluents. The formulated microbial beads are a ready to use as well as reusable seeding material in BOD analysis. The said beads can be reused up to 5 times with the same efficacy.

Rapid monitoring and assessment of pollutional load in dairy waste water

In the present scenario, an attempt was made to develop an ideal device (BOD biosensor) with computer-aided software capable of determining the varying BOD load of dairy waste waters and which facilitates instant monitoring. The shelf life of the developed biosensor was more than 400 days. The results of extensive testing of the developed BOD biosensor on dairy waste water over a period of time demonstrate that the BOD values obtained by the device are statistically correlated with conventional BOD values, irrespective of the varying load of waste water (which might occur as a result of different operations in industry). The developed BOD biosensor shows good reproducibility and repeatability over a period of time. Good correlation (r2 = 0.991) was observed between the values obtained from the developed sensor and conventionally estimated values. The repeatability of the measurements with the BOD biosensor dairy industrial waste water samples (inlet and outlet) was within a percentage deviation of ±10%.