A novel and sustainable approach for biotransformation of phosphogypsum to calcium carbonate using urease producing Lysinibacillus sphaericus strain GUMP2.

Phosphogypsum (CaSO4) is produced as a waste by-product during phosphoric acid production in the fertilizer industry. Only 15% of worldwide phosphogypsum production is recycled, while 85% is stored in the vicinity of factories as huge piles resulting in environmental and health hazards. An extensively studied biotransformation of phosphogypsum to calcium carbonate or calcite (CaCO3) using sulfate reducing bacteria (SRBs) is a prolonged process and results in the formation of extremely hazardous H2S gas. Here we report for the first time a novel approach for biotransformation of phosphogypsum to CaCO3 using urease producing Lysinibacillus sphaericus strain GUMP2. The strain could effectively transform phosphogypsum to crystalline, bead-shaped CaCO3 precipitates. In a batch reactor with the PG loading rate of 60 g/L, 100% biotransformation was observed within seven days. After calcite recovery, the ammonium sulfate formed in the supernatant was recovered by precipitation. Urease-producing L. sphaericus strain GUMP2 could be used to remove the hazardous phosphogypsum from the environment by converting it to the industrially useful CaCO3 and ammonium sulfate, a valuable agricultural fertilizer. This novel and sustainable approach could be a promising solution for the hazardous phosphogypsum in the phosphoric acid industries.

Diversity and functional annotation of microorganisms in French vertical flow constructed wetland treating greywater.

Constructed wetlands form a unique ecosystem having plants, soil, microbes in which microorganisms play a vital role in the transformation and degradation of pollutants from wastewater. In the present study, French type two-stage vertical flow constructed wetland (VFCW) was used for the treatment of single household greywater (GW). Pilot-scale VFCW having sand and gravel as the filter substrate was constructed with Canna indica plantation for treating GW. To understand the pollutant removal mechanism in VFCW, microbial diversity and functional annotation was carried out by metagenomics analysis of sequences obtained from illumina platform. Efficiency of VFCW was measured with respect to water quality parameters like COD, BOD5, Total Nitrogen, Nitrate, Nitrite, Ammoniacal-N, ortho-phosphate and TOC from inlet and outlet of system. The removal efficiency was 90%, 93%, 34%, 26%, 89%, 68%, 80%, and 80% for COD, BOD5, Total Nitrogen, Nitrate, Nitrite, Ammoniacal-N, ortho-phosphate and TOC respectively. Microbial diversity was much more diversified and unique in VFCW compared to GW. Metagenomes exhibited Proteobacteria and Bacteroidetes as major phyla in GW whereas Actinobacteria, Proteobacteria, Nitrospirae abundance in VFCW layers. Total of 809 and 695 genus were found in VFCW and GW respectively with minimum abundance of 10 hits. From functional annotation of sequences, VFCW microbes have the potential to transform various aromatic and xenobiotic compounds along with the removal of pollutants present in the form of Carbon, Nitrogen, and Phosphorus. These data reveal French type VFCW can efficiently treat GW and with its own unique, variable habitat VFCW harbours diverse community of microorganisms that transform and degrade the pollutants in GW.

Nutrient recovery and microbial diversity in human urine fed microbial fuel cell.

Presence of urine in municipal wastewater is a major problem faced by wastewater treatment plants. The adverse effects are noticeable as crystallization in equipment and pipelines due to high concentration of nitrogen and phosphorus. Therefore, improved technologies are required that can treat urine separately at the source of their origin and then discharge it in the main wastewater stream. In this study, the performance of the microbial fuel cell (MFC) was evaluated with mixed consortia and isolated pure cultures (Firmicutes and Proteobacter species) from biofilm for electricity generation and nutrient recovery. Microbes utilize less than 10% of total phosphorus for their growth, while 90% is recovered as struvite. The amount of struvite recovered was similar for pure and mixed culture (12 ± 5 g/L). The microbial characterization also shows that not all the biofilm-forming bacterial isolates are very much efficient in power generation and, hence, they can be further exploited to study their individual role in operating MFC. The different organic loading rates experiment shows that the performance of MFC in terms of power generation is the same for undiluted and five times diluted urine while the recovery of nutrients is better with undiluted urine, implying its direct use of urine in operating fuel cell.

Biodegradation of crude oil by Pseudomonas aeruginosa and Escherichia fergusonii isolated from the Goan coast.

Petroleum hydrocarbons are major pollutants of the marine environment. Bioremediation is a promising approach for treating such contaminated environments. The present study aims at isolating naturally occurring bacteria from the coast of Goa, India and to study their hydrocarbonoclastic capacity. Pseudomonas aeruginosa and Escherichia fergusonii were isolated from a crude oil-contaminated sediment sample using diesel oil as the sole carbon source. The capability of the enriched culture to degrade crude oil was estimated using microcosm studies under saline conditions. Based on GC-MS analysis, the culture was found to degrade n-alkanes at a higher rate compared to polyaromatic hydrocarbons. It was also found that the culture degraded alkylated polyaromatic hydrocarbons much less than unalkylated ones. Alkanes ranging from C12 to C33 were highly degraded compared to n-C34. This study shows bioremediation of crude oil in saline (3% NaCl) conditions by naturally existing bacteria isolated from the marine environment.