Sorption of humic substances and microbial activity in the course of artificial recharge of groundwater

Sorption of humic subtances and metal-humate complexes on aquifer material taken from basins used for artificial recharge of groundwater was studied in batch scale experiments. Distribution of bacteria attached to the material from uppermost layer and from the horizons below the infiltration basin were measured in the field studies. Sorption of aquifer material was heterogeneous in respect to the different position and depth in the infiltration basin. Sorption depended on the numerous factors including composition of the filter sand and properties of humic matter. The heavy metals retarded during artificial groundwater recharge was in the form of metal-humate complexes, dominantly in anionic form or as particulate matter. Sorption of humic substances on the aquifer material was substantially enhanced due to the forming of complexes with heavy metals. Total bacterial number was greatest on the upper most layer of infiltration basin. Slight decreases of bacterial number was observed down to the depth of two meters. There were no significant differences in ratio among major physiological groups of heterotrophic bacteria between layer investigated. The smallest seasonal variation of bacteria was found in the deeper layer below infiltration basin.Godkänd; 1999; 20070403 (ysko

Aspects of drinking water supply in areas of humic water

The thesis investigated several aspects that are important for drinking water supply from waters with high amounts of humic substance (humic water). The results showed that the composition of humic substances is important in their sorption to aquifer material during surface water artificial recharge through infiltration basins to groundwater. The more acidic fraction of humic substances was less effectively sorbed than the more hydrophobic fraction. The removal of the former fraction from the recharged groundwater was effective using weak base anion exchange resin. A high total number of bacteria in presence of cyanobacteria in the subsurface below the infiltration indicated that significant decrease of biodegradation of organic matter, during water passage from blooming humic lake to groundwater, is not likely. Because of high amounts of microbially assimilable organic carbon in humic water and its low reduction during chemical treatment, bacterial growth in drinking water distribution systems was dependent on the phosphorus concentration. In the distributed water bacteria were forming biofilm on the pipe surfaces. To reduce the biofilm growth fairly high doses of chlorine were needed. The anion exchange resin was successfully used to determine concentrations of iron-humic complexes in humic groundwater. According to this analysis a significant part of iron in drinking water, produced by artificial recharge from a humic lake, was bound to humic substances.Godkänd; 2002; 20061110 (haneit

Aspects of drinking water supply in areas of humic water

The thesis investigated several aspects that are important for drinking water supply from waters with high amounts of humic substance (humic water). The results showed that the composition of humic substances is important in their sorption to aquifer material during surface water artificial recharge through infiltration basins to groundwater. The more acidic fraction of humic substances was less effectively sorbed than the more hydrophobic fraction. The removal of the former fraction from the recharged groundwater was effective using weak base anion exchange resin. A high total number of bacteria in presence of cyanobacteria in the subsurface below the infiltration indicated that significant decrease of biodegradation of organic matter, during water passage from blooming humic lake to groundwater, is not likely. Because of high amounts of microbially assimilable organic carbon in humic water and its low reduction during chemical treatment, bacterial growth in drinking water distribution systems was dependent on the phosphorus concentration. In the distributed water bacteria were forming biofilm on the pipe surfaces. To reduce the biofilm growth fairly high doses of chlorine were needed. The anion exchange resin was successfully used to determine concentrations of iron-humic complexes in humic groundwater. According to this analysis a significant part of iron in drinking water, produced by artificial recharge from a humic lake, was bound to humic substances.Godkänd; 2002; 20061110 (haneit

Effect of Phosphorus on Survival of Escherichia coli in Drinking Water Biofilms▿

The effect of phosphorus addition on survival of Escherichia coli in an experimental drinking water distribution system was investigated. Higher phosphorus concentrations prolonged the survival of culturable E. coli in water and biofilms. Although phosphorus addition did not affect viable but not culturable (VBNC) E. coli in biofilms, these structures could act as a reservoir of VBNC forms of E. coli in drinking water distribution systems

The Effect of Chlorination on Escherichia Coli Viability in Drinking Water

The assessment of drinking water disinfection efficiency traditionally involves the estimation of faecal indicator inactivation rates in the form of reduction of cultivable counts. Widely described, viable but noncultivable (VBNC) state as a form of bacterial survival strategy in oligotrophic conditions is not considered in these estimations. The aim of the present research is to assess the effect of free chlorine disinfection on faecal indicator Escherichia coli in order to study the succession of cellular alterations in response to chlorine exposure. To determine the inactivation rates, cell ability to form colonies, ability to divide as such and metabolic activity have studied. 0.064 mg/L min-1 free chlorine has been needed to obtain 99 % inactivation of cultivable counts; however, 5 till 200 times higher disinfectant dose x contact time has been required to reduce cell ability to divide and metabolic activity, respectively. The results have shown that to determine correct drinking water disinfectant doses multiple cell viability parameters should be analyzed

Removal of total phosphorus, ammonia nitrogen and organic carbon from non-sterile municipal wastewater with Trametes versicolor and Aspergillus luchuensis

Discharge of organic load from treated wastewater may cause environmental eutrophication. Recently, fungi have gained much attention due to their removal of pharmaceutical substances by enzymatic degradation and adsorption. However, the fungal effect in removing nutrients is less investigated. Therefore, two fungal species, the white-rot fungus T. versicolor as a laboratory strain and the mold A. luchuensis as an environmental isolate from the municipal wastewater treatment plant, were studied to determine the fungal potential for phosphorus, nitrogen, and the total organic carbon removal from municipal wastewater, carrying out a batch scale experiment to a fluidized bed pelleted bioreactor. During the batch scale experiment, the total removal (99.9 %) of phosphorus by T. versicolor was attained after a 6 hours-long incubation period while the maximal removal efficiency (99.9 %) for phosphorus from A. luchuensis was gained after an incubation period of 24 hours.  Furthermore, both fungi showed that the pH adjustment to 5.5 kept the concentration of nitrogen constant and stabilized the total organic carbon reduction process for the entire incubation period. The results from the fluidized bed bioreactor demonstrated opposite tendencies on a nutrient removal comparing to a batch experiment where no significant effect on phosphorus, nitrogen, and total organics carbon reduction was observed. The obtained results from this study of batch and fluidized bed bioreactor experiments are a promising starting point for a successful fungal treatment optimization and application to wastewater treatment.QC 20210107</p

Natural Grasslands as Lignocellulosic Biofuel Resources: Factors Affecting Fermentable Sugar Production

Semi-natural grassland habitats are most often limited to animal grazing and low intensity farming. Their potential in bioenergy production is complicated due to the heterogeneity, variation, accessibility, and need for complex pre-treatment/hydrolysis techniques to convert into valuable products. In this research, fermentable sugar production efficiency from various habitats at various vegetation periods was evaluated. The highest fermentable sugar yields (above 0.2 g/g volatile solids) over a period of 3 years were observed from habitats “xeric and calcareous grasslands” (Natura 2000 code: 6120) and “semi-natural dry grasslands and scrubland facies on calcareous substrates” (Natura 2000 code: 6210). Both had a higher proportion of dicotyledonous plants. At the same time, the highest productivity (above 0.7 t sugar/ha) was observed from lowland hay meadows in the initial stage of the vegetation. Thus, despite variable yield-affecting factors, grasslands can be a potential resource for energy production

Impact of Rapid pH Changes on Activated Sludge Process

The inhibition effect of rapid variations of pH in wastewater on activated sludge was investigated in laboratory-scale sequencing batch reactors (SBR). The toxic influence of pH 6.5 and 8.5 was examined. The experiment with pH 8.5 was preferable to formation of high FA concentration and showed a low risk of inhibition of second step nitrification (conversion of nitrites to nitrates). However, the reactor at pH 6.5 showed inhibition of first-step nitrification (conversion of ammonia to nitrites) caused by FNA formation. High ammonia levels caused a decrease in the overall microfauna population, whereas low&ndash;enhanced gymnamoebae, Zoogloea, and Chilodonella sp. population increased after 72 h of inhibition. Destructive acidic pH influence caused sludge washout from the reactor and, therefore, higher organic load on ASP and intensive sludge foam due to Zoogloea higher population