| Activated sludge process is the main method to deal with wastewater in the world. However, if a large amount of residual sludge produced in the treatment process is not disposed properly, it will cause serious pollution to the environment. The terminal treatment method, such as landfill, incineration and composting can fundamentally achieve economic and efficient sludge disposal. Therefore, the establishment of a stable, safe, economy of excess sludge treatment method has become a hot research field.The oxic-settling-anaerobic(OSA) system is more stable and cheaper comparing with those methods before. But the disintegration efficiency of excess sludge in OSA system relies on the oxidation-reduction-potential(ORP) level. Hence, many researches are studied at-250 m V. However, this ORP level means a strictly anaerobic condition, which is difficult to implement in engineering. Moreover, the sludge reduction efficiency can hardly be increased because the ORP level cannot be lower than-250 m V. But some anaerobic microorganism can strengthen the disintegration process, and can break through the ceiling that ORP level brings.Our previous research presented that anaerobic microorganism was much more effective than anaerobic condition. And a better disintegration effect of the sludge was discovered only at the ORP level ranging from 0 to +50 m V. Cheng’s study got a good effect on sludge reduction in shake flask, whereas the treatment was small and batch processing. It needs more researches for increasing treatment capacity and disintegration efficiency before industrial application.Hence, the 4 L continuous anaerobic reactor was designed to solve the problems mentioned above. Nothing but a few anaerobic bacteria was added in. Except that, there are no any additional conditions like controlling ORP level or p H. It is very convenient to operate. A test using continuous treatment was implemented by adding 4 L of distilled water and 3 g of anaerobic bacteria into the reactor. The concentrations of COD, TP, NH4+-N, polysaccharide and protein were determined to study the disintegration effect of different hydraulic retention time(4 d, 3 d and 2 d) of sludge.Results showed that, the concentrations of SCOD, NH4+-N and TP, which can reflect the effect of disintegration, tended to rise with the anaerobic time and increase in HRT. And their trends were fast at first and then slow. When HRT was 3 d, the concentrations of COD, NH4+-N and TP increased from 72, 0.04 and 0.005 mg·L-1 to 3103, 3.11 and 3.88 mg·L-1, respectively. When HRT was 4 d, the concentrations of COD, NH4+-N and TP increased from 98, 0.06 and 0.133 mg·L-1 to 3310, 8.90 and 3.90 mg·L-1,respectively. And the mass of TP is equivalent. The concentrations of extracellular polymer also tended to rise with the anaerobic time and increase in HRT. When HRT was 3 d, the concentrations of protein and polysaccharide increased from 22.37 mg·L-1 and 5.37 μg·L-1 to 37.32 mg·L-1 and 83.78 μg·L-1, respectively.When HRT was 4 d, the concentrations of protein and polysaccharide increased from 42.94 mg·L-1 and22.69 μg·L-1 to 99.12 mg·L-1 and 377.83 μg·L-1, respectively. The concentrations of protein and polysaccharide can be used to weigh the degree of cell lysis.By adding enzymatic active material, we found that the inhibitory effect of Fe Cl3 on sludge disintegration and activated carbon powder effect on sludge disintegration up. During the addition of 5 g Fe Cl3, the sludge disintegration rate was 46.7%, the average daily amount of 1.06 g·L-1; during the addition of 0.5 g powdered activated carbon, sludge disintegration rate was 59.1%, the average daily amount of 1.34 g·L-1.The disintegration effect of the sludge was discussed to provide a theoretical reference for late pilot and sewage treatment plants. |
PDF Full Text Request