Concentration of Total Organic Carbon and Its Fractions in Surface Water in Poland and Germany

Total organic carbon (TOC) present in surface water consists of different fractions like dissolved organic carbon (DOC) or biodegradable dissolved organic carbon (BDOC). BDOC may have an impact on the bacteriological quality of water as it can be a source of carbon and energy for microorganisms. It is important to consider this parameter in case of the distribution of drinking water. The aim of this research was to compare the qualities of chosen surface water in Poland and Germany in terms of concentration of total organic carbon and its fractions. The samples were taken from the reservoir in Poland and Rhine River in Germany. The first one is a source of drinking water for humans. The research showed that, considering the analyzed compounds, the water from the river has better quality.

Preliminary investigation into the claims of the IBROM system

Membrane filtration is commonly applied to reduce dissolved organic carbon (DOC) to control the formation of trihalomethanes (THMs); however, high levels of DOC can cause severe fouling of reverse osmosis membranes. The integrated biological and reverse osmosis membrane (IBROM) process is a combination of biological filters and reverse osmosis membranes. The IBROM process claims to remove biodegradable dissolved organic carbon (BDOC), which apparently should result in reduced membrane fouling. The goal of this research was to conduct a preliminary investigation into the claims of the IBROM system, using water collected from the Herbert water treatment plant (Saskatchewan). The plant is utilizing the IBROM for the treatment of a dugout and groundwater blend (DOC of 17.5–22.7 mg/L). The results demonstrated that BDOC concentrations did not change significantly throughout the plant. Optimized laboratory-scale coagulation with polyaluminium chlorohydrate achieved 58% removal of BDOC. Oxidation with permanganate increased the concentration of BDOC (from 5.7 to 8.8 mg/L). Overall, BDOC was effectively removed by optimized coagulation rather than the IBROM system. Moreover, the results show an inverse relationship between BDOC and THMs formation potential (THMFP) in both coagulated and oxidized water. For all concentrations, more biodegradable DOC had less tendency to form THMs based on the lower THMFP.

Application of multivariate methods and geoestatistics to model the relationship between CO2 emissions and physicochemical variables in the Hidrosogamoso reservoir, Colombia

Aim This article deals with the estimation of a model for CO2 emissions in the Hidrosogamoso reservoir based on the organic matter level and water quality. This is in order to determine the impact of the creation of a tropical reservoir on the generation of greenhouse gases (GHG), and to establish the water quality and emissions dynamics. We hypothesize that the spatial variability of emissions is determined by water quality and carbon cycling in water. Methods Multivariate techniques were applied to determine the relationships between CO2 and certain physicochemical variables measured in the reservoir between February and May 2015, taking samples in 10 stations and measuring 14 variables (water quality parameters and CO2). Factor, cluster, discriminant and regression analysis, as well as the geostatistical technique kriging, were used. Results We observed that all variables except dissolved organic carbon have strong linear relationships. Nitrate, total-P, total solids and total suspended solids are related due to the presence of nutrients in the water; chlorophyll a and biodegradable dissolved organic carbon due to organic carbon; and alkalinity and dissolved solids due to dissolved minerals. The sampling stations can be classified into two homogeneous groups. The first consists of the stations peripheral to the reservoir and the second of stations inside the reservoir. This difference is due mainly to the behavior of chlorophyll a and biodegradable dissolved organic carbon, and these two variables are also the best predictors for CO2, with a maximum adjustment of 70%. Conclusions Our main conclusion is that the production of CO2 is due to decomposition of flooded organic carbon, depends on the soils flooded and the tributary water quality, and that the production of this gas will, based on the literature, continue for 5 to 10 years depending on the nature of the forest flooded.

Biomass development in GAC columns receiving influents with different levels of nutrients

Indigenous bacteria are essential for the performance of bio-filters for drinking water treatment. Yet it is slow and difficult to develop biofilm in a granular activated carbon (GAC) filter with low nutritional levels in the influent, especially during winter. In this study, the biofilm development in three laboratory-scale GAC columns with different types of influent was investigated in southeast China during winter. The results indicated that nitrogen was the limiting factor for biofilm development in GAC columns for this source water. The biomass density in the column with ammonia nitrogen addition was much higher than those of the other two filters, while its microbial diversity and biological activity were lower. Moreover, the ammonia-feeding column also showed the highest removal of organic contaminants during the stable operating periods, i.e. chemical oxygen demand (CODMn), assimilable organic carbon as well as biodegradable dissolved organic carbon. Therefore, nitrogen amendment favors the formation of biofilm. It could shorten the start-up time of a GAC filter and enhance the bio-stability of its effluent. This might add some new insights towards the operation of GAC filters with low nutritional levels in the influent during winter.

Removal Characteristics of Organic Pollutants from Eutrophic Raw Water by Biological Pretreatment Reactors

Two biological contact oxidation reactors, cascade biofilm reactor (CSBR) and one-step biofilm reactor (OSBR), were used in this paper for pretreatment of eutrophic water from Lake Taihu in China. The CSBR was more effective and stable for eutrophic water treatment than OSBR, in terms of extracellular microcystin-LR,chlorophyll-a, DOC, and biodegradable dissolved organic carbon (BDOC) removal. Removal efficiencies of extracellular microcystin-LR andchlorophyll-a were 75.8% and 59.7% in CSBR and 60.5% and 53.0% after 2 h in OSBR. CSBR had much higher removal efficiency (34.3%) than OSBR (22.7%) for DOC, and CSBR could remove 67% BDOC, accounting for 34% of total DOC in source water. 11.5% of DOC was removed through means other than biological degradation, such as biofilm adsorption and bioflocculation. In CSBR at 5.5~13°C, 57.5% of atrazine was removed at 2 h hydraulic retention time, with background concentration of 136.5 ng/L. Meanwhile, removal efficiencies of three phthalic acid esters (PAEs) (dimethyl phthalate, di-(2-ethylhexyl) phthalate, and di-n-butyl phthalate) were 78.7%, 52.4%, and 85.3%, respectively. Only 35.2% of polycyclic aromatic hydrocarbons (PAHs) could be removed by CSBR with initial concentration of 21.5 μg/L. The results indicated that CSBR is effective in low-molecular-weight organic pollution pretreatment and provides benefits in terms of effluent quality.

Changes in water biostability levels in water treatment trials

This article presents the results of studies of changes in water biostability levels in water treatment systems. In order to evaluate the potential of microorganism regrowth, both the organic and non-organic nutrient substrate content was taken into account. Pre-treatment in the analyzed water treatment plants ensured high phosphate ion removal effectiveness but a significantly worse effectiveness in removing biodegradable dissolved organic carbon (BDOC). Lowering nutrient substrate content during the main treatment stage was only possible in water treatment systems that incorporated biological processes. Conversely, final water treatment processes only influenced BDOC content in the treated water. Irrespective of the water type and unit treatment process, the limiting factors for microorganism regrowth in the distribution system were the phosphate ion content and BDOC content. However, none of the analyzed treatment systems ensured a reduction in non-organic nitrogen content that would ensure biological stability of the water.