Effect of Alkalinity Type and Concentration on Nitrifying Biofilm Activity

Abstract

The effect of alkalinity on nitrifying biofilm activity was determined by collecting twenty-one day old biofilm samples from a full-scale nitrifying trickling filter and evaluating bench-scale nitrate plus nitrite generation rates at (1) various initial carbonate alkalinity concentrations and (2) with four types of available alkalinity; carbonate only, phosphate only, phosphate plus hydroxide, and phosphate plus carbonate alkalinity. Initial carbonate alkalinity concentrations were varied between 308 and 20 mg/L as CaCO 3 . Ammonia, nitrite, and nitrate concentrations were measured at time zero, 90 minutes, 180 minutes, and 270 minutes. Generation rates in g N/m 2 *day were calculated for each time period and normalized against dry weight biomass. The effect of the initial carbonate alkalinity concentration on generation rate was evaluated by twotailed ANOVA followed by LSD analysis at a 95% confidence interval. Generation rates were impaired at initial alkalinity concentrations at and below 40 mg/L as CaCO 3 and were unaffected at concentrations of 45 mg/L and above. This is consistent with Gujer and Boller's (1984) proposal and Szwerinski's et al. (1986) data that alkalinity is rate limiting below 1-2 millimoles/liter or 50-100 mg/L as CaCO 3 . For reactor runs with different alkalinity types, ammonia, nitrite, and nitrate concentrations were measured at time zero and at 375 minutes. Generation rates were calculated and normalized against dry weight biomass measurements. The effect of alkalinity type on generation rate was evaluated by two-tailed ANOVA followed by Tukey analysis. The type of alkalinity, carbonate versus phosphate, affected nitrification rates. If the carbonate alkalinity was below 45 mg/L, nitrification rates were impaired regardless of the total alkalinity. This effect seems to be independent of pH for the range of 6.92 to 7.99 evaluated here. This would suggest that in addition to neutralizing the acid generated by the nitrification process, a minimum level of carbonate alkalinity is necessary to meet the ammoniaoxidizer's inorganic carbon requirement for cellular synthesis and growth.

Effect of using sodium bicarbonate to adjust the pH to different levels on water quality, the growth and the immune response of shrimpLitopenaeus vannameireared in zero-water exchange biofloc-based culture tanks

“…Based on the review provided by amount of researchers’ studies, the pH has influences on nitrification. But poor agreement existed on how much, and at what point, pH begins to affect nitrification rates (Biesterfeld, Farmer, Russell & Figueroa ). The optimal range of pH for nitrification can be determined by the three different effects that the pH can exert on nitrifying bacteria: (i) activation–deactivation of nitrifying bacteria, (ii) nutritional effect, connected with alkalinity, (iii) inhibition through free ammonia and free nitrous acid (Villaverde, Garcia‐encina & Fdz‐Polanco ).…”

Partial nitrification using aerobic granule continuous-flow reactor: Operations and microbial community

“…Thus, influent ammonia loading rates influenced the end products being nitrite or nitrate for ammonia laden wastewater treatments by sludge [4] or by granular sludge [10]. Controlling nutrient concentration could be used as a controlling parameter to partial nitrification [14,15]. Additionally, the presence of organic carbon determined the activities of heterotrophic denitrifier, hence affecting the end product distributions for the reactor [16].…”

Desempenho de Sistema Combinado Anaeróbio-Aeróbio na Remoção de Nitrogênio no Tratamento de Esgoto Sanitário

“…Cabe salientar, segundo Biesterfeld et al (2003) a taxa de nitrificação depende da concentração de carbono inorgânico (isto é, alcalinidade bicarbonato) sugerindo que o mínimo requerimento de alcalinidade é função da necessidade de carbono para síntese celular e não necessariamente refere-se a requerimentos de neutralização de acidez gerados pelo processo de nitrificação.…”