For reference:
1. Foreword
The pickling process of pickled Chinese sauerkraut in Taiwan Province is often accompanied by wastewater containing high salinity. In the early days, pickled Chinese sauerkraut barrels were all set beside farmland. After 45 days of pickling, farmers will directly pour the pickled Chinese sauerkraut wastewater containing high salinity into farmland, which often leads to serious salinization of soil, resulting in inability to cultivate and serious environmental pollution.
At present, the way to treat these wastewater is heat treatment, which is to heat the wastewater to remove moisture and achieve the purpose of reducing the amount, but it consumes a lot of energy and increases the cost of wastewater treatment. If anaerobic treatment can be used to convert the organic matter in saline wastewater into usable methane, and then methane can be used as fuel for its heating treatment, the treatment cost will be reduced.
However, the salt in wastewater often inhibits the growth of microorganisms, so biological treatment is difficult. Lefebure (2116) pointed out that if salinity is slowly added to wastewater to make microorganisms adapt, microorganisms can be treated in saline wastewater, but at present, there are not many studies on the influence of salinity on methanogens and methane production, so the purpose of this study is:
1. To explore the maximum salinity that bacteria can bear and
2. To explore methane production, organic matter removal rate and salinity.
ii. experimental equipment and methods
(I) experimental equipment
in this study, we used an anaerobic filter bed, and the anaerobic digestion system was set up, including anaerobic reaction tank, inflow and outflow equipment, gas measurement and collection equipment produced by strains, temperature control and filling media. In order to cooperate with the experiment of saline wastewater, the bottom mud of seawater shrimp pond was domesticated and taken out as a strain to treat saline wastewater. The waste water is artificial waste liquid, which is domesticated before entering batch experiments, and the salt concentration is gradually increased in each batch. The artificial waste water is stored in a refrigerator at 4℃ to avoid microbial breeding.
(II) Experimental methods
1. Start-up test
At the beginning of the experiment, the strain growth was observed without adding salt, and HRT was slowly increased. When sampling, the supernatant was taken out to detect its PH and COD, and its gas output and methane content were recorded.
the second stage is salinity test, in which the gas output is recorded before each inflow, and then 1c.c gas is extracted from the gas sampling bottle and injected into the gas chromatograph (GC8711T-TCD, China Chromatography, Taiwan Province) for gas analysis. After the gas analysis is completed, the inflow and outflow procedures are carried out:
(1) Sampling: shake the reactor to make it uniform, then take out 511 ml of liquid, and then take out the supernatant after 2 minutes of natural precipitation, and take out the flow rate of the day with a measuring bottle.
(2) inflow: after sampling, add the inflow artificial waste liquid, and pump the excess supernatant back to the reaction tank to maintain the total volume of the reaction tank of 5 liters.
2. Test of adding salt
The experiment of adding salt was carried out in three batches of 1.5%, 1.1% and 3.1% respectively (Figure 1). In this study, samples were taken twice a day, and each sample was analyzed for pH, COD and TDS respectively. In the experiment of saline wastewater, TS and salinity were measured.
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