[Effects of Phosphorus on the Activity and Bacterial Community in Mixotrophic Denitrification Sludge].

Biological denitrification is now one of the most widely applied techniques to remove nitrogen from the aquatic environment, and mixotrophic denitrification has gained attention as it takes the characteristics of both heterotrophic and autotrophic denitrification. This study investigated the biological denitrification efficiency and the bacterial community structure of sludge sampled from a mixotrophic denitrification reactor, before and after adding a certain amount of phosphate. The results showed that the bacteria have the capability of denitrification even without phosphorus, but the addition of phosphorus could significantly improve the biomass and the denitrification activity.

Effects of hydraulic retention time and [Formula: see text] ratio on thiosulfate-driven autotrophic denitrification for nitrate removal from micro-polluted surface water.

This study was carried out to investigate the possibility of a thiosulfate-driven autotrophic denitrification for nitrate-N removal from micro-polluted surface water. The aim was to study the effects of [Formula: see text] ratio (S/N molar ratio) and hydraulic retention time (HRT) on the autotrophic denitrification performance. Besides, utilization efficiencies of [Formula: see text] along the biofilter and the restart-up of the bioreactor were also investigated.

Effects of HRT and water temperature on nitrogen removal in autotrophic gravel filter.

Organic Carbon added to low ratio of carbon to nitrogen (C/N ratio) wastewater to enhance heterotrophic denitrification performance might lead to higher operating costs and secondary pollution. In this study, sodium thiosulfate (Na2S2O3) was applied as an electron donor for a gravel filter (one kind of constructed wetland) to investigate effects of hydraulic retention time (HRT) and water temperature on the nitrate removal efficiency. The results show that with an HRT of 12 h, the average total nitrogen (TN) removal efficiencies were 91% at 15-20 °C and 18% at 3-6 °C, respectively.

[Study on the start-up of anaerobic ammonium oxidation process in biological activated carbon reactor].

In order to shorten the start-up time of anaerobic ammonium oxidation (ANAMMOX) reactor, biological activated cabon reactor was applied. Three lab scale UASB reactors were seeded with anaerobic sludge, fed with synthetic wastewater containing ammonia and nitrite, and supplemented with granular activated carbon on day 0, 33 and 56, respectively. The nitrogen removal performance of the first reactor, into which GAC was added on day 0, showed no significant improvement in 90 days.

[Study on sulfur-based autotrophic denitrification with different electron donors].

Sulphur-based autotrophic denitrification was applied to treat the low concentration nitrate-contaminated water. Different electron donors, namely, elemental sulfur, sulfide and thiosulfate, were used in three continuous reactors to compare the denitrification performance. When treating the low concentration nitrate-contaminated water (13 mg x L(-1)), the thiosulfate system showed the best performance and the sulfide system was the worst.

Nitrogen removal in micro-polluted surface water by the combined process of bio-filter and ecological gravel bed.

Nitrogen removal in micro-polluted surface water by the combined process of a bio-filter and an ecological gravel bed was studied. Sodium acetate was added into micro-polluted surface water as carbon source and the nitrogen removal under different C/N ratio, hydraulic load and temperature were investigated. The results showed that the variations in C/N ratio, hydraulic load and temperature have significant influence on nitrogen removal in bio-filter.

Effects of iron on growth and intracellular chemical contents of Microcystis aeruginosa.

Objective: To investigate the effect of iron on the growth, physiology and photosynthesis of cyanobacteria.

Methods: A gradient of iron concentrations was employed to investigate the growth, photo-pigments (chlorophyll A and phycocyanin), and cell chemical contents (C, N, P) of Microcystis aeruginosa in response to different iron additions.

Results: The specific growth rate during the exponential growth phase, as well as the cell chlorophyll A and the phycocyanin content, was limited by iron below 12.

[Early-warning and prediction technology of harmful algal bloom: a review].

Harmful algal bloom (HAB) occurs frequently and causes serious damage. To study the early-warning and prediction technology of HAB is of significance for the early-warning and prediction, ecological control, and disaster prevention and mitigation of HAB. This paper reviewed the research progress in the early-warning and prediction technologies of HAB, including transport prediction, specific factors critical value prediction, data-driven model, and ecological math model, and evaluated the advantages and disadvantages of these four types of technologies.

Factors affecting simultaneous nitrification and de-nitrification (SND) and its kinetics model in membrane bioreactor.

Experiments have been carried out to investigate the effect of biological factors such as dissolved oxygen (DO), food/microorganism (F/M) ratio, carbon/nitrogen (C/N) ratio and pH on performance of SND in membrane bioreactor (MBR). It was found that a low DO was advantageous to SND on condition that nitrification was not inhibited, while F/M ratio and C/N ratio have reverse effects on SND, and pH should also be controlled in a suitable range. Based on the conventional activated sludge model, a deduction was conducted to illustrate that SND could take place from the theoretical aspect, and it was proved that high organics was effective in improving SND.

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment.

Zeolite synthesized from fly ash (ZFA) without modification is not efficient for the purification of NH4+ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.

The performance of BAF using natural zeolite as filter media under conditions of low temperature and ammonium shock load.

Natural zeolite and expanded clay were used as filter media for biological aerated filter (BAF) to treat municipal wastewater in parallel in whole three test stages. The stage one test results revealed that zeolite BAF and expanded clay BAF have COD and NH(3)-N removals in the range of 84.63-93.

Improving the performance of sequencing batch reactor (SBR) by the addition of zeolite powder.

Two types of operation means "SBR reactor alone (control reactor)" and "adding zeolite powder into SBR reactor (test reactor)" were used to treat municipal wastewater. The test results revealed that zeolite powder addition could improve the activity of the activated sludge. It was investigated the specific oxygen utilization rate (SOUR) of the tested zeolite sludge were about double times that of the control activated sludge, and the nitrification rate and settling property of zeolite-activated sludge were both improved.

[Factors affecting biological removal of iron and manganese in groundwater].

Factors affecting biological process for removing iron and manganese in groundwater were analyzed. When DO and pH in groundwater after aeration were 7.0 - 7.

Activated sludge ozonation to reduce sludge production in membrane bioreactor (MBR).

Total experimental period was divided into two stages. At first stage, a series of batch studies were carried out to get an understanding of the effect of ozonation on sludge properties. At the following stages, three membrane bioreactors (MBRs) with different amounts of activated sludge to be ozonated were run in parallel for a long period to evaluate the influence of sludge ozonation on sludge yield and permeate quality.

Biological nitrogen removal with enhanced phosphate uptake in (AO)2 SBR using single sludge system.

Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor ((AO)2 SBR). The system showed stable phosphorus and nitrogen removal performance, and average removals for COD, TN and TP were 90%, 91% and 96%, respectively. The conditions of pH 7.

Determination of operational parameters of anaerobic phase for enhanced phosphorus removal in MBR.

Two runs of experiments were carried out to obtain an understanding of phosphorus release and uptake under the anaerobic condition and then the aerobic condition respectively. Under anaerobic condition, it was found that the extent of phosphorus release appeared to increase with the increase of the initial organic loading rate when the initial organic loading rate was up to 0.1 gSCOD/gMLSS.

Treating both wastewater and excess sludge with an innovative process.

The innovative process consists of biological unit for wastewater treatment and ozonation unit for excess sludge treatment. An aerobic membrane bioreactor (MBR) was used to remove organics and nitrogen, and an anaerobic reactor was added to the biological unit for the release of phosphorus contained at aerobic sludge to enhance the removal of phosphorus. For the excess sludge produced in the MBR, which was fed to ozone contact column and reacted with ozone, then the ozonated sludge was returned to the MBR for further biological treatment.

A novel approach to treat combined domestic wastewater and excess sludge in MBR.

Domestic wastewater was treated by combined anaerobic biofilm-aerobic membrane bioreactor(MBR) process, and part biomass MBR was withdrawn to treat with ozone, then the ozonated sludge was returned to anaerobic inlet. In aerobic MBR, MISS and DO were controlled at 3000-3500 mg/L and 0.8 mg/L respectively.