Using natural biomass microorganisms for drinking water denitrification

• Published in: Journal of environmental management 2018-07, Vol.217, p.520-530
• Main Authors: Costa, Darleila Damasceno, Gomes, Anderson Albino, Fernandes, Mylena, Lopes da Costa Bortoluzzi, Roseli, Magalhães, Maria de Lourdes Borba, Skoronski, Everton
• Format: Article
• Language: English
• Subjects: Carbon source; Denitrification; Natural biomass; Nitrate; Nitrite; Potability
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2018.03.120

Among the methods that are studied to eliminate nitrate from drinking water, biological denitrification is an attractive strategy. Although several studies report the use of denitrifying bacteria for nitrate removal, they usually involve the use of sewage sludge as biomass to obtain the microbiota. In the present study, denitrifying bacteria was isolated from bamboo, and variable parameters were controlled focusing on optimal bacterial performance followed by physicochemical analysis of water adequacy. In this way, bamboo was used as a source of denitrifying microorganisms, using either Immobilized Microorganisms (IM) or Suspended Microorganisms (SM) for nitrate removal. Denitrification parameters optimization was carried out by analysis of denitrification at different pH values, temperature, nitrate concentrations, carbon sources as well as different C/N ratios. In addition, operational stability and denitrification kinetics were evaluated. Microorganisms present in the biomass responsible for denitrification were identified as Proteus mirabilis. The denitrified water was submitted to physicochemical treatment such as coagulation and flocculation to adjust to the parameters of color and turbidity to drinking water standards. Denitrification using IM occurred with 73% efficiency in the absence of an external carbon source. The use of SM provided superior denitrification efficiency using ethanol (96.46%), glucose (98.58%) or glycerol (98.5%) as carbon source. The evaluation of the operational stability allowed 12 cycles of biomass reuse using the IM and 9 cycles using the SM. After physical-chemical treatment, only SM denitrified water remained within drinking water standards parameters of color and turbidity. •Bamboo is natural biomass which provides microorganisms for water denitrification.•Nitrate is fully removed by microorganisms from bamboo without nitrite accumulation.•Methanol is not an adequate carbon source compared to ethanol, glycerol and glucose.•Using suspended cells from bamboo is more attractive than use the whole biomass.