Investigation of nitrite accumulation by hydrogenotrophic denitrification in a moving bed biofilm reactor for partial denitrification and anammox process.

The partial denitrification and anammox (PDA) process has received attention for its ability to optimize treatment of wastewater containing a low NH-N concentration. This study investigated the suitable operational conditions for NO-N accumulation by hydrogenotrophic denitrification (HD) in operation of a laboratory-scale moving bed biofilm reactor, for future application in the PDA process. NO-N accumulation was achieved by minimizing the H flow rate under optimized conditions (i.

Distribution and Community Composition of Anammox Bacteria in Shallow Groundwater of the Kathmandu Valley, Nepal.

The abundance and diversity of anaerobic ammonium oxidation (anammox) bacteria were assessed in 152 groundwater samples in the Kathmandu Valley, Nepal. Anammox bacterial 16S rRNA genes were detected in 54% (37/68) of samples collected in the dry season at 1.6×10-8.

Newly established process combining partial hydrogenotrophic denitrification and anammox for nitrogen removal.

The anaerobic ammonium oxidation (anammox) process holds great promise for treating nitrogen-contaminated water; stable nitrite-nitrogen (NO -N) production is significant to anammox performance. In this study, partial hydrogenotrophic denitrification (PHD) was used to stably and efficiently produce NO -N from nitrate-nitrogen (NO -N). An investigation of the effects of initial pH on the PHD process revealed that a high NO -N production efficiency (77.

Coupled anaerobic ammonium oxidation and hydrogenotrophic denitrification for simultaneous NH-N and NO-N removal.

Nitrate removal during anaerobic ammonium oxidation (anammox) treatment is a concern for optimization of the anammox process. This study demonstrated the applicability and long-term stability of the coupled anammox and hydrogenotrophic denitrification (CAHD) process as an alternative method for nitrate removal. Laboratory-scale fixed bed anammox reactors (FBR) supplied with H to support denitrification were operated under two types of synthetic water.

Development of an objective water security index and assessment of its association with quality of life in urban areas of developing countries.

A composite metric assessing water security's physical dimension at the micro/ community level is lacking but is essential for setting priorities for program and policy implementations. We prepared an objective index (OI) of water security to measure the physical dimension using a model centered on household water-use behavior in developing countries' urban areas. A cross-sectional household survey (n = 1500) with multi-stage cluster design was conducted from December 2015 to February 2016 in the Kathmandu Valley, which has faced long-term, severe water shortage.

Development of an attached growth reactor for NH₄-N removal at a drinking water supply system in Kathmandu Valley, Nepal.

Higher concentrations of ammonium (NH(4)-N) and iron (Fe) than a standard for drinking are typical characteristics of groundwater in the study area. To remove NH(4)-N and Fe, the drinking water supply system in this study consists of a series of treatment units (i.e.

Characterization of microbial communities distributed in the groundwater pumped from deep tube wells in the Kathmandu Valley of Nepal.

Although groundwater is a major water supply source in the Kathmandu Valley of Nepal, it is known that the groundwater has significant microbial contamination exceeding the drinking water quality standard recommended by the World Health Organization (WHO), and that this has been implicated in causing a variety of diseases among people living in the valley. However, little is known about the distribution of pathogenic microbes in the groundwater. Here, we analysed the microbial communities of the six water samples from deep tube wells by using the 16S rRNA gene sequences based culture-independent method.

Effects of inorganic carbon limitation on anaerobic ammonium oxidation (anammox) activity.

Anammox bacteria are chemoautotrophic bacteria that oxidize ammonium with nitrite as the electron acceptor and with CO(2) as the main carbon source. The effects of inorganic carbon (IC) limitation on anammox bacteria were investigated using continuous feeding tests. In this study, a gel carrier with entrapped anammox sludge was used.

Effects of nitrite inhibition on anaerobic ammonium oxidation.

In order to assess the stability of nitrogen removal systems utilizing anaerobic ammonium oxidation (anammox), it is necessary to study the toxic effects of nitrite on these biochemical reactions. In this study, the effects of nitrite on anammox bacteria entrapped in gel carriers were investigated using batch and continuous feeding tests. The results showed that the nitrite concentration in a reactor must be less than 274-mg N/L in order to prevent a decrease in the anammox activity, which occurred when the gel carriers were soaked in nitrite solutions with concentrations greater than 274-mg N/L in a batch test.

Quantification of anammox populations enriched in an immobilized microbial consortium with low levels of ammonium nitrogen and at low temperature.

Anaerobic ammonium oxidizing (anammox) bacteria present in microbial communities in two laboratory-scale upflow anoxic reactors supplied with small amounts of ammonium (<3 mg/l) at low temperature were detected and quantified. The reactors, operated at 20 degrees C, were seeded with an immobilized microbial consortium (IMC) and anaerobic granules (AG) from an upflow anaerobic sludge blanket (UASB) treating brewery wastewater. Our results showed that complete ammonium and nitrite removal with greater than 92% total nitrogen removal efficiency was achieved in the reactor inoculated with both the IMC and AG, while that of the reactor inoculated with only the IMC was lower than 40%; enrichment was successful after the addition of AG.

Long-term dynamics of freshwater red tide in shallow lake in central Japan.

Objective: The aim of this study is to clarify the long-term dynamics of the red tide occurring in Lake Kawaguchi.

Methods: The measurement of environmental factors and water sampling were carried out monthly at a fixed station in Lake Kawaguchi's center basin from April 1993 to March 2004. On June 26, 1995, the horizontal distribution ofPeridinium bipes was investigated using a plastic pipe, obtaining 0∼1-m layers of water column samples at 68 locations across the entire lake.

Presence and activity of anammox and denitrification process in low ammonium-fed bioreactors.

A combination of anammox and denitrification process was studied for 300 days in low ammonium-fed bioreactors under the support of organic carbon. Nutrient profiles, (15)N-labelling techniques and qualitative fluorescence in situ hybridization (FISH) probes were used to confirm the nitrogen removal pathways and intercompetition among different bacteria populations. About 80% of nitrogen removal was achieved throughout the study period.

Ferrates (iron(VI) and iron(V)): environmentally friendly oxidants and disinfectants.

Iron(VI) and iron(v), known as ferrates, are powerful oxidants and their reactions with pollutants are typically fast with the formation of non-toxic by-products. Oxidations performed by Fe(VI) and Fe(V) show pH dependence; faster rates are observed at lower pH. Fe(VI) shows excellent disinfectant properties and can inactivate a wide variety of microorganisms at low Fe(VI) doses.