The Experimental Research On The Treatment Of Acid Coal Mine Drainage By Indigenous Microorganism In Loess

China is a big coal-mining country where the water resources are insufficient.Through mining,the precious underground water is turned into discharged acid drainage,which in turn pollutes clean surface water, underground water and land resources,does harm to crops,to aquatic lives as well as to human health.If the acid drainage is utilized reasonably and turned into something hazardless,not only can water and land resources be protected but also drainage can be turned into useful water resources,which is of the first importance to China,the western area in particular.At home and abroad,the acid drainage from coal mines is disposed mainly by drainage plants,which has the main disadvantages of large investment in infrastructure and equipment,high cost in operation and small treatment volume. Consequently,coal mines,particularly those dispersively distributed township mines can hardly afford the cost and it is meaningful to do research in reducing treatment cost of drainage.The mid-western areas of China boast abundant loess,where live a great amount of microorganisms such as sulfate-reducing bacteria.If the bacteria are activated by supplementing base carbon source to enable them to reproduce abundantly,then ACMD can be reclaimed through natural loess-microorganism system,which lowers investment by a large margin.Furthermore,the treatment means is applicable and easy to be popularized.The thesis selects typical Malan loess(Q₃),Lishi loess(Q₂)and the waste water discharged from the coal mines of the townships and towns in Xiaoyi County,Shanxi Province as research objects in order to study on the feasibility that indigenous bacteria in loess is activated to reduce sulfate by supplementing carbon source and then the loess-microorganism system is utilized to treat acid waste water from mines.In this research,static and dynamic simulation experiments are made at room temperature respectively in sealed containers and unsealed soil columns by adding carbon source to the system,which proves that our train of thought is feasible.After the analysis to the experiment results,the following conclusions can be drawn:(1)The method that loess-microorganism system treats ACMD through supplementing carbon source to activate indigenous sulfate-reducing bacteria in soil is feasible.The experiments prove that the maximum removal rate of SO₄^2- is 94.2%in static simulation experiments(original concentration 2800 mg/L) and 95.5%in dynamic experiments(original concentration 2200 mg/L)by loess-microorganism systems.Degradation of SO₄^2-is faster in dynamic experiments than that in static ones. (2)In static simulation experiments,the maximum removal rate of SO₄^2-is larger in Malan loess(94.2%)than that in Lishi loess(74.3%)by SRB.The removal efficiency reaches the maximum when Malan loess is added into 1200 mg/L glucose,while the removal efficiency reaches the maximum when Lishi loess is added into 800 mg/L glucose.(3)In dynamic simulation experiments,carbon source comes from low organic sewage.The Malan and Lishi loess columns do not provided the reduction environment for the growth of SRB so that the microorganism in loess cannot be activated.The removal of SO₄^2-mainly depends on the loess itself, failing to producing effective and lasting removal effect.(4)In dynamic simulation experiments at room temperature(14～19℃),high organic sewage provides carbon source for the system.The Malan loess column at the depth of 20cm develops the reduction environment and the highest removal efficiency of SO₄^2-is 67%.While the Lishi loess column turns rapidly into the reduction environment from the oxidation state and the depth of 20cm obtains the maximum removal efficiency of SO₄^2-95.5%on 82 d.Therefore,the removal rate of SO₄^2-is lowered as the depth increased.The treatment effect of Lishi loess column to acid drainage is better than that of Malan less column.