Rapid Granulation Of Hypersaline Arobic Sludge And Its Characteristics

Hypersaline industrial wastewater has the characteriatics of high concentration of pollutants and difficult to deal with. Arobic granular sludge is especially suitable for handing hypersaline and high-stength wastewater for its excellent settling characteristics, strong anti-pollution load capacity and so on. But at present, rapid formation mechanism unclear and the stability problem during operation are technical bottleneck to hinder arobic granular sludge dealing with industrial wastewater into engineering applications. This thesis is to research rapid granular mechanism of hypersaline arobic sludge, sludge characteristics and stable system operation measures under different conditions.The seed sludge of this thesis is the activated sludge from a sewage treatment plant in Chongqing city. This experiment is conducted in six identical SBR reactors under different conditions to form a hypersaline (3%) arobic granular sludge. By examining the change trend of sludge settling characteristics, dehydrogenase activity, ammonia removal and EPS on the sludge granulation process. The influence of C/N ratio and organic load during the formation of the primary particles of sludge, the particle mature process and physicochemical properties under different flocculant added and salt stress mode are researched. At the same time, granulation mechanism and filamentous bulking control measures in the different periods are researched and explored.The results of this study as follows:①During the culture period of primary particles, by the dual control of C/N ratio and the organic load, the system is relatively stable, protein content continues to increase, settling characteristics and microbial activity both are in a good state. To21d, the primary particles formed, sludge volume index (SVT) is30.23ml/g, the smallest sedimentation rate (VS)minis3.45m/h, dehydrogenase activity is46.75ugTF·gSS-1·h-1, ammonia nitrogen removal rate is56.24%.②All the particles of SVI value in the end of the test are less than50mg/L, and (VS)min are greater than2m/h. The SVI of granular sludge in R3is the minimum which under1.5%-3%-2.4%-3%salt stress and without flocculant, for13.83ml/g. At the same time, its (VS)min is the maximum, for13.80m/h. flocculant adding and the salt promoting stage one at1.5%-1.5%-1.5%salt stress both promote the growth of the particles. With the process of particles, granular sludge of excessive growth is prone to filamentous bulking. Therefore, controling the excessive growth of the particle size is very important for the stable operation of the latter part.③At the end of the test, the dehydrogenase activity of granular sludge in R4is the maximum which under0.5%-l%-1.5%-2.4%-3%salt stress and within flocculant, the value up to26.68ugTF·gSS-1·h-1, but under the condition of ammonia water penetration concentration of225mg/L, the ammonia nitrogen removal rate in R3is better than other reactors which under1.5%-3%-2.4%-3%salt stress and without flocculant, the value up to71.83%. According to the stability of long-term operation and decontamination performance, R3is the best way to build.④With the process of test, the granular sludge protein (PN) and PN+polysaccharide (PS) content is gradually increased. The flocculant promote the secretion of protein in the extracellular polymeric substances (EPS), but counterproductive to PS. The distribution of mature particle size is similar to the normal distribution, and the particle size of filamentous bacteria is the biggest, radiodurans is the smallest. The average size of mature particle is positively related to dispersion of particles, and microorganisms’phase of the interior of the particles has a relationship with particle size.⑤The formation of the primary particles in this test is comprehensive results of metal ion hypothesis, filamentous bacterium hypothesis and EPS hypothesis. However, in the the particle maturation process, the microorganisms self-aggregation, the webs effect of metal ions and EPS jointly promote mature granulation. Filamentous bacteria have little effect in particle maturation process.⑥During the period of the primary particles, lower C/N ratio and the low-to-high gradient load promoting operation mode effectively control the expansion trend. During the period of the mature particles, raising the pH and dissolved oxygen (DO) have little effect in inhibition of filamentous bulking. Smaller particle size and larger proportion of granular sludge can effectively control filamentous bulking by just regulation of C/N; relatively speaking, larger particle size and smaller proportion of granular sludge, we need to further lower the load to get quite satisfactory regulation effect.This thesis is the study of rapid granulation of hypersaline aerobic sludge and sludge characteristics which provide a theoretical help for the treatment of high salt industrial waste water in the future, and a reference for the practical application of engineering.