Evaluation of microalgal-bacterial consortia for waste water treatment

Poonam

Evaluation of microalgal-bacterial consortia for waste water treatment

Date

2023

Authors

Poonam

Publisher

Punjab Agricultural University

Abstract

This study investigated the bioremediation abilities of microalgae and bacteria for the treatment of domestic waste water. Two microalgal viz. PL1 and PL2 and eight bacterial strains viz. B1(L1), B2(L1), B3(L1), B4(L1), B1(L2) B2(L2), B3(L2) and B4(L2) were isolated form indigenous population i.e L1 & L2. Both the microalgae isolates had a long exponential phase and continued to remain in this phase till the end of experimental growth period i.e. 30 days. Log phase of all bacterial isolates were observed at 60 hours of incubation except B1(L1) (48 hours). After screening, two microalgae i.e. PL1 & PL2 and four bacterial isolates were selected for efficient wastewater treatment. B1(L1), B3(L1), B2(L2) and B4(L2) were observed to be efficient in wastewater treatment than other bacteria under study. Coexistence of each strain with other was seen without any trace of growth inhibition which represented their compatibility. From the total of 29 tested consortia, most potential consortium was selected based on the treatment efficacy after 15 days of treatment. Developed consortium no. 29 i.e. PL1+PL2+B4(L2) was selected for domestic wastewater treatment as it showed significant percent reduction among all combinations i.e. BOD (82.9%), COD (77.77%), EC (53.8%), TDS (74.3%),Total nitrogen (71.05%) and Total Phosphorus (69.25%). Higher percent reduction in BOD (88.90%), COD (82.35%) was recorded with selected consortia 29 when treatment provided with source of aeration in 30 days of treatment. SEM observations revealed that several bacterial cells were attached to microalgal cells over 10 days of incubation and it led to the conclusion that microalgae PL1 & PL2 and bacteria B4(L2) can live together and efficiently treat wastewater. Molecular identification of members of consortia 29 was performed. It was revealed after 18S rRNA sequencing PL1 was identified as Chlorella variabilis, PL2 was tentatively identified as Desmodesmus and after 16S rRNA sequencing B4(L2) was identified as Paracoccus sp.. Sequence of PL1 and B4(L2) was submitted to NCBI GenBank with accession no. OR122520.1 and OR467496, respectively. Thus, present study concluded that microalgae and bacteria have more potential to treat wastewater when they were applied in form of consortia. The selected developed consortia no. 29 showed highest percent reduction in all physiochemical parameters with source of aeration in 30 days of wastewater treatment. Nevertheless, the assessment of polluted water composition should be completed prior to the designing and application of microalgae or cyanobacteria based remediation technology, since the pollutant removal efficiency is found to be essentially species dependent.

Citation

Poonam (2023). Evaluation of microalgal-bacterial consortia for waste water treatment (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.