Relationship between Phytoplankton, Heterotrophic Plankton, and Planktivorous Fish Productions in Different Water Bodies.

Examination of 14 lake-type water bodies at various latitudes of the Northern Hemisphere showed that the efficiency of phytoplankton production transformation through heterotrophic bacterioplankton and non-predatory zooplankton to predatory zooplankton and planktivorous fish increases in the direction from eutrophic to oligotrophic water bodies. The highest ratios between autotrophic and heterotrophic organism production were observed in lakes and reservoirs where the contribution of allochthonous substances to the total energy flow is relatively high. Bacterioplankton utilizing allochthonous dissolved organic matter (DOM) provides an additional source of energy for zooplankton, which serves as food for planktivorous fish. Therefore, to predict the total biological productivity and production of the fish community, it is necessary to take into account the production of not only autotrophic plankton, but also that part of heterotrophic bacterioplankton that is specialized in utilizing DOM entering the water body from the outside.

A simple and low-cost resazurin assay for vitality assessment across species.

Working with biological organisms requires knowledge about the state of their viability and vitality to ascertain efficient processes. The phenoxazine dye resazurin is routinely used for viability assessment of many different species. Here, a novel use for resazurin as an indicator for vitality assessment across several species is proposed. Different amounts of biomass as well as mixtures of live/dead biomass were investigated for their capabilities of metabolizing resazurin and monitored over time. Increasing (live) biomass was found to increase reaction rate in a linear fashion, giving information about the cells' vitality. In an application example, stored suspension cultures of Sporosarcina pasteurii were found to decrease in viability over time, while urease activity decreased as well. For the first time, the assessment of vitality by one technique was demonstrated for several species in parallel.

Effect of low COD/N ratios on stability of single-stage partial nitritation/anammox (SPN/A) process in a long-term operation.

This study investigates the effects of varying COD/N ratios on single-stage partial nitritation/anammox (SPN/A) process in a SBR. The operational period was divided into three phases with different influent COD/N ratios (0.4, 0 and 0.5). Stable nitrogen removal was achieved in phase I with a COD/N of 0.4. In phase II COD was absent, effluent nitrite and nitrate increased and nitrogen removal performance gradually deteriorated. In phase III SPN/A failed to recover from nitrate accumulation when COD/N was increased. Microbial activity was measured and microbial community was analyzed by high-throughput sequencing. These results revealed that ordinary heterotrophic organisms (OHO) was suppressed when influent COD was absent, leading to the promotion of nitrification even at a low DO (0.2mgL-1). Therefore, nitrite oxidizing bacteria (NOB) was gradually enriched and anammox bacteria was suppressed. Besides, it was observed that flocs were sensitive to influent COD variations than granules, which requires further investigation.

Biological nutrient removal with limited organic matter using a novel anaerobic-anoxic/oxic multi-phased activated sludge process.

An anaerobic-anoxic/oxic (A2/O) multi-phased biological process called "phased isolation tank step feed technology (PITSF)" was developed to force the oscillation of organic and nutrient concentrations in process reactors. PITSF can be operated safely with a limited carbon source in terms of low carbon requirements and aeration costs whereas NAR was achieved over 95% in the last aerobic zone through a combination of short HRT and low DO levels. PCR assay was used for XAB quantification to correlate XAB numbers with nutrient removal. PCR assays showed, high NAR was achieved at XAB population 5.2 × 10(8) cells/g MLVSS in response to complete and partial nitrification process. It was exhibited that low DO with short HRT promoted XAB growth. Simultaneous nitrification and denitrification (SND) via nitrate were observed obviously, SND rate was between 69-72%, at a low DO level of 0.5 mg/l in the first aerobic tank during main phases and the removal efficiency of TN, [Formula: see text], COD, TP was 84.7 .97, 88.3 and 96% respectively. The removal efficiencies of TN, [Formula: see text], and TP at low C/N ratio and DO level were 84.2, 98.5 and 96.9% respectively which were approximately equal to the complete nitrification-denitrification with the addition of external carbon sources at a normal DO level of (1.5-2.5 mg/l).