Operation Characteristics Of Spiral Symmetric Stream Anaerobic Bioreactor For Treating Organic Saline Wastewater

Organic saline wastewater refers to wastewater with high salinity（salinity>1 wt%）and high organic matter concentration（COD>2000 mg/L）.Over the years,saline wastewater has been discharged in large volumes from industrial facilities producing agro-food,leather and petrochemicals.It is reported that such wastewater may account worldwide for as much as 5%of all wastewaters requiring treatment,and the value continue to increase.Many salts contained in organic saline wastewater will harm the anaerobic microorganisms.Current technologies for the treatment of saline organic wastewater include evaporation,membrane filtration and their improved techniques.While the current technologies usually have the disadvantages of high costs and low removal.In this study,a Spiral Symmetry Stream Anaerobic Bioreactor（SSSAB）was adopted for treating actual saline heparin sodium pharmaceutical wastewater（HSPW）.This research use SSSAB adapted microorganisms to degrade organic saline wastewater and investigate the anaerobic degradation pathway of HSPW,analyze the mechanism of salt tolerance of the microflora,and coupled CNT with KCl to promote the anaerobic biodegradation of organic saline wastewater.The conclusion of this study was as follow:（1）Although high osmotic pressure caused by salt contents inhibits anaerobic microorganisms,a high salt tolerance and efficient treatment can still be achieved by SSSAB.The SSSAB can operate efficiently and stably in treating actual HSPW.Finally,with a COD of 8731mg/L,an OLR of 6.98 kg COD/（m3·d）and a salinity of 3.57 wt%,the COD removal reached 82%.This value was higher than other reactors reported in the existing literature under similar salinity.The benzene series are the main organic matter in HSPW,and the rate-limiting steps for a degradation of benzene series in HSPW are the degradation of phenol and p-cresol.（2）The microbial flora in SSSAB became more specialized in treating saline organic wastewater since the salt-tolerant microbe became more dominant,such as bacteria Mesotoga,Anaerophaga,Oceanotoga and Aminobacterium.The salt-tolerant model of salt-tolerant bacteria was constructed.The model shows that if the external salinity is constant,the concentration of solutes secreted or accumulated by microorganisms is inversely proportional to the salinity diffusing into the EPS.The larger the i/（θ（T,c）） value is,the more solutes that microorganisms need to secrete or accumulate,which indicates that promoting the transfer of compatible solutes and salt ions and strengthening the protective effect of compatible solutes in EPS on microorganisms are the key to further improving the treatment efficiency of high-salt organic wastewater by anaerobic biological methods.（3）The addition of CNT can promote the anaerobic biodegradation of organic saline wastewater,and the simultaneous addition of CNT and KCl in the matrix is better than only adding CNT or KCl.The batch experiment shows that under the salinity of 20 g/L and 30 g/L,simultaneous dosing of 2 g/L of CNT and 1.5 g/L of KCl can significantly promote the anaerobic biodegradation of wastewater.After 72 hours of reaction,the COD removal rate increased by 16.6%and 10.6%respectively compared with the control group.In the anaerobic continuous flow test,the addition of CNT and KCl has slightly promoting effect on the anaerobic biological treatment of salt-containing organic wastewater,which is higher than the anaerobic treatment effect of only adding KCl.