Treatment of Pickled Mustard Wastewater by Using the Halotolerant Anaerobes
Date Issued
2011
Date
2011
Author(s)
Lin, Jyun-Yao
Abstract
Pickled mustard wastewater must be treated prior to discharge or it will severely pollute the environment because of its high salinity and organic contents. To solve this problem, this study proposed using the acclimated anaerobic sludge from the seawater shrimp pond to treat this saline wastewater.
In the beginning, the anaerobic sludge was acclimated using the synthetic wastewater and through gradually step-increasing salt contents, these anaerobic bacteria were able to adapt to the saline environment. After acclimation, different tests of using 5, 7 and 10% of synthetic saline wastewater, and 6 and 9% of dilute pickled mustard wastewater were conducted. Both types of wastewater were operated at HRTs of 5 days and 10 days.
When fed with 10% salt of synthetic wastewater, and operated at 10 days HRT and 4 g COD/L/day of organic loading rate, the performance results showed that pH dropped from 7.25 to 5.04 and COD removal efficiency was decreasing from 95.3% to 64.6% after 24 days. It indicated that the growth of anaerobic bacteria would be inhibited if the pH was not adjusted suitably for the high salt content wastewater.
For tests of feeding dilute pickled mustard wastewater, the HRT were sequentially operated at 10 and 5 days with the OLR of 0.64 and 1.24 g COD/L/day, respectively. In test of 6% salt wastewater and 10 days HRT, 72% of the COD removal efficiency, and 0.15 L/L/day of GPR (gas production rate) and 0.09 L CH4/L/day of MPR (methane production rate) were achieved. With the same 6% salt wastewater, in test of 5 days HRT, a better performance results of 75% of the COD removal efficiency, and 0.38 L/L/day of GPR (gas production rate) and 0.21 L CH4/L/day of MPR (methane production rate) were achieved. It clearly indicated that, at 6% salt content, increasing OLR will improve the gas production GPR and MPR effectively. Comparing the results of HRT 5 days and 10 days, GPR and MPR were lifted up to 3.17 and 2.73 times, respectively.
When feeding 9% salt content of dilute pickled mustard wastewater, in test of 10 days HRT, the OLR was increasing to 0.85 g COD/L/day. Both GPR and MPR were increasing to 0.28 L/L/day and 0.19 L CH4/L/day, respectively, and 78% of the average COD removal efficiency and 72% of methane content were achieved. It showed that no indication of inhibiting the anaerobic bacteria under the condition of 10 days HRT and 9% of salt content. However, in test of 5 days HRT with the same 9% salt content, the pH kept on decreasing to 5.18 and the COD removal efficiency was decreasing to only 18%. The gas production was affected either, both GPR and MPR were decreasing to 0.26 L/L/day and 0.10 L CH4/L/day, respectively, and the methane content was decreasing to 40%. Therefore, in treatment of the high salt content wastewater, the anaerobic reactor should be operated at a longer HRT, i.e., a lower OLR. In summary, this study provides a new method by using the acclimated anaerobic sludge treated the pickled mustard wastewater and produced the combustible methane gas successfully.
Subjects
Pickled mustard wastewater
Anaerobic
Halotolerant bacteria
Methane
SDGs
Type
thesis
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