Navicula densilineolata, this species is an optimum indicator for oligosaprobity at pH 7 or more alkaline pH and less than 100 mg/L chloride ion （Cl－）. However, there are many species resembling this species in size and shape of valve. For this reason, it is confused that the author who first announced this taxon proposes status change of this species few years later. In this paper, we researched the morphological variability and revealed the distinction points against 19 approximate species with the photographs of 230 valves of this species obtained in Lake Ikeda （Kagoshima Prefecture, Japan）. Finally, we created a description of this species.

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The full-scale constructed wetland treating wastewater from PET bottle recycle plant was investigated and its treatment performance for 29 months was evaluated. This constructed wetland may be the first full-scale system to treat industrial wastewater other than from livestock industry. The lab-scale experiment reproducing the clogging happened in the constructed wetland was also performed to clarify factors causing clogging. It was found that the BOD₅：N：P ratio in raw wastewater was 100：0.30－0.43：0.01－0.02, which proportion of nitrogen and phosphorus against BOD₅ were significantly lower compared with reasonable proportion for biofilm formation and plant growth. The BOD₅, COD_Cr, T－N, T－P, and SS removal efficiencies for 29 months were 78, 77, 76, 81, and 65％, respectively. The treatment performance fluctuated, and BOD₅ and COD_Cr removal efficiencies did not always satisfied National Effluent Standards. The treatment performances in the second year, especially during the winter seasons were quite low. It was because of overflow involved in clogging. Based on the biodegradable property of organic polymer flocculating agent （OPFA） and the results of lab-scale experiment, it was indicated that the clogging was caused by OPFA used for a pre-treatment of effluent from waste PET bottle washing process. These results suggest that the property of OPFA should be considered when coagulation sedimentation process is used for a pre-treatment of constructed wetland.

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This study investigated the influence of enrichment temperature on the accumulation ability of polyhydroxybutyrate (PHB) and the composition of PHB－accumulating microorganisms (PHBAMOs) in mixed microbial cultures obtained from activated sludge. PHBAMOs were enriched using the feast-famine method in sequencing batch reactors that were fed with acetate as the sole external carbon source and controlled at 20℃ or 28℃. Batch PHB accumulation experiments under nitrogen- and phosphorus-deficient conditions revealed that the maximum content and yield of PHB in the two enrichment cultures were twice as high as the seed sludge. The results indicated that the PHB accumulation ability of the sludge can be greatly enhanced by enrichment using the feast-famine method, irrespective of temperature. Through clone library analysis targeting the phaC genes, PHBAMOs belonging to Rhodocyclales, specifically Thauera, were found to be notably increased after enrichment, although Burkholderiales were dominant in the seed sludge. The increase of PHBAMOs belonging to Rhodocyclales was greater in the enrichment culture obtained at 20℃, which had a slightly stronger PHB accumulation ability, as compared with that at 28℃. These results suggest that Rhodocyclales may be the key members enhancing PHB accumulation abilities of the enrichment cultures.

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A mathematical model was developed for predicting effects of temperature on nitrogen removal in continuous-flow reactors via anaerobic ammonium oxidation (anammox). A cardinal temperature equation with inflection for the bacterial growth was incorporated into the anammox model of low-temperature type reactors, Low－R1 and Low－R2 inoculated with activated sludge respectively in Kumamoto and Hokkaido. The maximum specific growth rate (μ_opt) was calibrated to 0.052 d^－1 at the optimal temperature (T_opt) of 26℃ between the minimum temperature (T_min) of 4℃ and the maximum temperature (T_max) of 36℃ for anammox bacteria in Low－R1 (correlation with measured data, r = 0.851). The values of μ_opt, T_opt, T_min, and T_max were calibrated to be 0.089 d^－1, 31℃, 0℃, and 36℃, respectively for anammox bacteria in Low－R2 (r = 0.995). A typical exponential temper ature equation was incorporated into the anammox model of a moderate-temperature type reactor, Mod－R inoculated with activated sludge in Kumamoto. The maximum specific growth rate at 30℃ was calibrated to 0.055 d^－1 with the temperature coefficient of 0.104℃^－1 for anammox bacteria in Mod－R (r = 0.987). The mathematical model simulated treatment of ideal wastewater containing ammonium at 50 mg－N/L and nitrate at 60 mg－N/L at hydraulic retention time of 0.5d and sludge retention time (SRT) of 50－150d at 10－30℃. The simulations predicted stable nitrogen removals in Low－R1 and Low－R2 at low temperatures in comparison with Mod－R. Although Low－R1 at short SRTs showed lower nitrogen removals than Mod－R at high temperatures around 35℃, Low－R2 demonstrated robust T－N removals in the whole temperature range. In conclusion, the low-temperature type anammox reactors, especially Low－R2, would have a sufficient potential to develop a versatile nitrogen removal process without any heating system in mild climate conditions.

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