I. Introduction
The process of pickling sauerkraut in Taiwan is often accompanied by wastewater with high salt content. In the early stage, because of the sauerkraut pickling barrels are set up next to the farmland, after 45 days of pickling and taking out the finished product of the sauerkraut, the farmers will pour the wastewater with high salt content directly into the farmland next to the sauerkraut, which often causes serious salinization of the soil and leads to the impossibility of cultivation, resulting in serious environmental pollution.
Currently, these wastewaters are treated by thermal treatment, which heats the wastewater and removes the water to reduce the amount of water, but uses a lot of energy and increases the cost of treating the wastewater. If you can use anaerobic treatment, the organic matter in the saline wastewater into a usable methane, and then use methane as a fuel for its heating treatment, it will reduce its treatment costs.
However, salinity in wastewater often inhibits the growth of microorganisms, making biological treatment difficult, and Lefebure (2006) showed that slow addition of salinity to wastewater to allow microorganisms to acclimatize can give microorganisms the ability to treat salty wastewater, but not many studies have been done to examine the effects of salinity on methanogens and methane production, and therefore, the purpose of this study was to:
This study was conducted to determine the effects of salt on methanogens in the treatment of saline wastewater. The purpose of this study is to:
1. explore the maximum salinity that the bacteria can tolerate and
2. explore the relationship between methane yield, organic matter removal rate and salinity, which can be used as a reference for the future design of saline wastewater treatment programs.
II. Experimental Equipment and Methods
(I) Experimental Equipment
In this study, we used an anaerobic filter bed, and the setup of anaerobic digestion system, including anaerobic reactor tank, inlet and outlet flow equipment, gas measurement and collection equipment produced by strains of bacteria, temperature control, and filler media. In order to match this saline wastewater experiment, the substrate of a seawater shrimp pond was used, which was domesticated and then taken out as the strain for saline wastewater treatment. Wastewater is artificial waste liquid, after domestication and then into the batch experiments, each batch will gradually increase the concentration of salt, artificial wastewater configuration stored in 4 ℃ refrigerator to avoid microbial breeding.
(2) Experimental methods
1. Start-up test
At the beginning of the experiment, the first operation in the absence of salt, to observe the growth of strains, and slowly increase the HRT, take out the upper clarified solution to detect the PH and COD, record the gas production, and methane content.
The second stage is salinity test, before each inlet and outlet, the gas yield was recorded, and then 1 c.c. of gas was taken from the gas sampling bottle and injected into the gas chromatograph (GC8700T-TCD, China Chromatography, Taiwan) for gas analysis. After completing the gas analysis, the inlet and outlet flow procedure is carried out:
(1) Sampling: Shake the reactor to make it homogeneous, then take out 500 ml of liquid, and then take out the upper clarified liquid after 2 minutes of natural sedimentation, and take out the outflow rate of the day by using the measuring bottle.
(2) Inflow: After sampling, add the artificial waste liquid into the inflow, and pump the excess liquid back into the reactor tank to maintain the total volume of the reactor tank at 5 liters.
2. Salt addition test
The salt addition test was conducted in three batches of 0.5%, 1.0% and 3.0% (Figure 1). In this study, samples were taken twice a day and each sample was analyzed for pH, COD and TDS, while TS and salinity were added when the test was conducted for saline wastewater.
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