[Distribution Characteristics and Environmental Driving Factors of Cyanobacteria Community in Impounded Lakes and Reservoirs in Shandong on the East Route of South-to-North Water Diversion Project].

To investigate the distribution characteristics of the cyanobacteria community and the driving factors in impounded lakes and reservoirs in Shandong on the east route of the South-to-North Water Diversion Project, monthly samples of phytoplankton and the aquatic environment from Nansi Lake, Dongping Lake, Datun Reservoir, Donghu Reservoir, and Shuangwangcheng Reservoir were collected from May to November during 2010 to 2019. A total of 44 planktonic cyanobacteria taxa were identified with 23 filamentous cyanobacteria taxa. Pseudanabaena limnetica, Cylindrospermopsis raciborskii, Microcystis aeruginosa, and Microcystis wesenbergii were the dominant harmful cyanobacteria species, with a high detection frequency and abundance in all lakes and reservoirs. By analyzing the distribution characteristics of the cyanobacteria community in impounded lakes and reservoirs, we found that filamentous cyanobacteria had growth advantages in the water with large hydraulic disturbances, which should be the key points of cyanobacteria prevention and control in the future. Pearson correlation analysis and generalized linear fitting curve results showed that total nitrogen, total phosphorus, water temperature, and water depth played a key role in affecting the growth of P. limnetica, C. raciborskii, M. aeruginosa, and M. wesenbergii. The nitrogen and phosphorus nutrients could promote the growth of harmful cyanobacteria. Due to the good temperature adaptability, P. limnetica could still become the dominant species in early summer and late autumn, and C. raciborskii, M. aeruginosa, and M. wesenbergii had growth advantages when the water temperature was higher than 25℃. In addition, shallow water was more conducive to the growth of C. raciborskii. It was suggested that based on strengthening of the control of nitrogen and phosphorus nutrient input in lakes and reservoirs, the key monitoring of P. limnetica in lakes should be conducted in early summer and late autumn, and the growth of C. raciborskii in shallow water areas should be paid close attention in the high temperature period to ensure the safety of water quality.

The behaviors of Microcystis aeruginosa cells and extracellular microcystins during chitosan flocculation and flocs storage processes.

This work aimed to study the effects of chitosan on cell integrity and extracellular microcystins (MCs) of Microcystis aeruginosa cells during flocculation and flocs storage processes. The impacts of chitosan addition, flocculation stirring and flocs storage time were comprehensively detected to prevent or reduce cell lysis and MCs release. Response surface method (RSM) was applied to optimize the chitosan flocculation. Under chitosan concentration 7.31 mg/L and optimized mechanical conditions, 99% of M. aeruginosa cells were integrated removed. Furthermore, amounts of extracellular MCs were adsorbed by chitosan polymers in this process. With chitosan flocs protect, though cells showed some damage, extracellular MCs concentration in flocculated samples lower than background level within first 2 d. However, lots of MCs release was observed after 4d which may result from chitosan degradation and cells lysis. Therefore, chitosan flocs should be treated within 2d to prevent the adsorbed MCs releasing again.

A multi-technique approach for the quantification of Microcystis aeruginosa FACHB-905 biomass during high algae-laden periods.

A pronounced dominance of toxic cyanobacteria has been found in eutrophic water bodies, with Microcystis being a common species. Although toxic cyanobacteria are commonly described worldwide, few recent papers on the sensitive and effective quantification of cyanobacteria have been published. In this paper, a multi-technique approach was applied by the use of cell density counting, cell viability testing, chlorophyll a determination, microcystin monitoring and gene extraction techniques to quantitatively analyse the cyanobacterial biomass of Microcystis aeruginosa FACHB-905. The entire dataset was used to examine the relationships between these indices. Results showed that, for 10(7) viable cells in the experimental conditions, the contents of chlorophyll a, microcystin-LR and total genes (16S rDNA) averaged 2.65 microg, 0.61 microg and 0.79 microg, respectively. For different cell viability proportions in the same particular phase of growth, it is easy to obtain the respective amount of viable cells and inactive cells and their measurable indices when any one of the three indices, chlorophyll a, DNA or microcystin-LR, is measured. This study provides a new perspective and method for determining multiple indices of toxic cyanobacteria during the same conditions and phases.

Effect of protease and cellulase on the characteristic of activated sludge.

Sludge dewatering is a key part of sludge disposal since it can greatly reduce the volume of sludge and thus improve the treatment effect for handling and disposing. This study investigated the potential benefits of enzymatic pretreatment on activated sludge dewatering with protease and cellulase as a protein and polysaccharide degrading enzyme, respectively. Capillary suction time (CST) and the solid content after centrifugation were used to evaluate sludge dewatering. The particle size distribution, extracellular polymeric substances (EPS) content, infra-red (IR) spectrometry and microscope image were determined in an attempt to explain the observed changes in sludge dewaterability. The results indicated that adding protease and cellulase separately leads to an increase in CST and the increased value is higher with protease. Protease and cellulase both promote the degradation of protein and polysaccharide in the solids of activated sludge, leading to a smaller particle diameter and poorer dewaterability. However, due to the limited effects on the protein and polysaccharide content, the difference in sludge dewaterability is not large. Compared to the control, enzymatic pretreatment had no obvious effect on sludge IR spectrometry, while there was a detectable structure difference at a colloidal scale.

[Effect of 2-aminophenol and 3,3',4',5-tetrachlorosalicylanilide on biomass yield of activated sludge].

The effects of 2-aminophenol and 3,3',4',5-tetrachlorosalicylanilide on biomass yields were studied. The results shows that when AP is 15 mg/L and TCS is 1.2 mg/L, observed growth yields (Yobs) of the sludge are reduced by 21% and 52% with low reduction of COD removal efficiency. Removal rates of ammonia decrease by 32% with TCS but are not affected obviously by AP. The effects of AP and TCS on dewater ability and settle ability of sludge were also investigated. The dewater ability of sludge is not affected by the two uncouplers. The SVI values of sludge with TCS increase slightly. According to microscope observation, the sludge microbe population changes. Meanwhile quantities and kinds of protozoan and metazoan were reduced.

Alga-lysing bioreactor and dominant bacteria strain.

Alga-lysing bacteria have been paid much attention to in recent years. In this study, the alga-lysing strain P05 which was isolated from an immobilizing biosystem was immobilized by coke and elastic filler, forming two biological reactors. The removal efficiencies of algae, NH4(+)-N and organic matter using the two reactors were studied. The results showed that strain P05 was an ideal algal-lysing bacteria strain because it was easy to be immobilized by coke and elastic filler which are of cheap, low biodegradability and the simple immobilization procedure. After 7 d filming, the biological film could be formed and the reactors were used to treat the eutrophic water. These two reactors were of stability and high effect with low cost and easy operation. The optimal hydraulic retention time of each reactor was 4 h. The algae removal rates were 80.38% and 82.1% (in term of Chl-a) of coke reactor and filler reactor, respectively. And that of NH4(+)-N were 52.3% and 52.7%. The removal rates of COD(Mn) were 39.03% and 39.64%. The strain P05 was identified as Bacillus sp. by PCR amplification of the 16S rRNA gene, BLAST analysis, and comparison with sequences in the GenBank nucleotide database.

Isolation and algae-lysing characteristics of the algicidal bacterium B5.

Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillus fusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that: (1) the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; (2) the algal-lysing effects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesmus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 x 10(7) cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 microg/L, about 70% was removed; (3) the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.

[Dewaterability and particle size distribution of activated and digestion sludge].

The dewaterability and particle size distribution of activated and digestion sludge were studied. Meanwhile, the related mechanism was explored through analyzing the extracellular polymeric substances (EPS) content and microbe characteristic of activated and digestion sludge. The dewaterability was evaluated using the capillary suction time (CST) and settling property. The CST of activated sludge and digestion sludge are 9.84 s and 607.5 s, respectively. The settling time of the solids of digestion sludge is longer than that of activated sludge. The major reason of poor dewaterability of digestion sludge is the degradation of carbohydrate and protein parts of EPS. In addition, the quantity of protozoan in digestion sludge is less than that of activated sludge, resulting in reducing the excretion of certain matters benefiting the agglomeration between microbes. The EPS content of digestion sludge is 123 mg/g, which was 77% less than that of activated sludge. The degradation of EPS during the digestion process leads to the smaller particle size of digested sludge, and then the poorer dewaterability. The particle size that occupied maximum volume in activated sludge is 133 microm, while it is 44.6 microm in digestion sludge. The mean particle size of activated sludge is 132.6 microm which is larger than that of digestion sludge (70.48 microm).

Degradation characteristics of two Bacillus strains on the Microcystis aeruginosa.

The degradation kinetics of strains P05 and P07 and the degradation effects of mixed strain on Microcystis aeruginosa were studied. The results showed that: (1) The degradation processes of strains P05 and P07 on Microcystis aeruginosa accorded with the first-order reaction model when the range of Chl-a concentration was from 0 to 1500 microg/L. (2) The initial bacterium densities had a strong influence on the degradation velocity. The greater the initial bacterium density was, the faster the degradation was. The degradation velocity constants of P05 were 0.1913, 0.2175 and 0.3092 respectively, when bacterium densities were 4.8 x 10(5), 4.8 x 10(6), 2.4 x 10(7) cells/ml. For strain P07, they were 0.1509, 0.1647 and 0.2708. The degradation velocity constant of strain P05 was higher than that of P07 when the bacterium density was under 4.8 x 10(5) cells/ml, but the constant increasing of P07 was quicker than that of P05. (3) The degradation effects of P05 and P07 strains did not antagonize. When the concentration of Chl-a was high, the degradation effects of mixed strain excelled that of any single strains. But with the decrease of the Chl-a concentration, this advantage was not clear. When the concentration was less than 180 microg/L, the degradation effects of mixed were consistent with that of strain P07.