Research On Sediment Characteristics Of Yellow River And Treatment Effect

The Yellow River is the river with the largest sediment concentration and highest turbidity in the world.The sediments can be classified into sedimentary sediments and suspended sediments depending on the state of existence.The sediments of the Yellow River have a large specific surface area and the complex interface effects with the organic pollutants discharged into the river.There are many active substances on the rough and porous surface,which Enhanced adsorption and degradation of pollutants by sediment.Therefore,the sediment became the main carrier of pollutants in the river for its diffusion,migration and transformation,thus affecting the ecological environment of the river flowing through the region.The study of the sediment's adsorption and degradation mechanism has a great significance to the ecological environment of the Yellow River.This paper taked the Yellow River's sediment in the Lanzhou as the research object,started from its physical and chemical characteristics,and studied its relationship with the turbidity of the water.Used the traditional kinetic experimental methods and isothermal balance experimental methods,the law of adsorption of COD_mnn in the Yellow River sediment was discussed.With the influencing factors,a model that can better simulate the adsorption behavior of COD_mnn in the Yellow River sediment was obtained.The relevant thermodynamic state functions were calculated and the adsorption mechanism and adsorption capacity were analyzed.The adsorption and degradation capacities of COD_mnn on the sediments of the Yellow River were investigated by adsorption kinetics and thermodynamics methods.The differences in the adsorption and degradation capacities of sedimentary sediments?sediments?and suspended sediments?suspensions?were compared.Response Surface Methodology was used to study the optimal treatment effect and influencing factors of the turbidity water of the Yellow River?Summer,Winter?by different methods such as coagulation,filtration and micro-flocculation.Get the following conclusions:?1?The sediment of the Yellow River not only tended to produce large turbidity,but also leaded to a higher total dissolved solids content in the water.The Yellow River sediment contained high COD_mn,total nitrogen and total iron,especially the total number of bacteria was exceeded the standard,indicating that the Yellow River water was more seriously polluted by organic matter,while abundant organic substances and nutrients provided a good living environment for bacteria.?2?Soil and water loss was the direct source of turbidity of the Yellow River.Soil and water loss along the Yellow River in different seasons caused a huge change in the turbidity of the Yellow River.With the differences in sediment content,season,time,and turbulence,the turbidity of the Yellow River would showed different changes.Experiments had shown that the turbidity of the water was corresponded to the increase of sediment concentration,stirring time,and stirring intensity.The increase,which decreased with the increase of the static precipitation time,indicated that due to the large gap between the upper reaches of the Yellow River and the high flow velocity,severe turbulence conditions were another cause of high turbidity;the sedimentation performance of the Yellow River sediment was very significant,and the difficulty in handling was relatively high.Small,because the sediment was mainly dominated by minerals.?3?Adsorption and migration of organic matter by the Yellow River sediment was the main mode of self-purification of water.The main factors influencing the COD_mnn absorption of water from the Yellow River sediment were sediment concentration,temperature and rotation speed.Using BBD response surface method to predict the maximum concentration of COD_mnn in the upper reaches of the Yellow River with the concentration of 7mg/L,the optimal effect of COD_mnn adsorption on the Yellow River sediments was as follows:sediment dosage is 2.6g/L,rotation speed was 204r/min,temperature At 25?,the maximum removal rate of COD_mnn was 38.83%,and the maximum adsorption capacity of COD_mnn per unit sediment was1.09 mg/g.?4?The adsorption law of COD_mnn on the sediment of the Yellow River indicates that the adsorption capacity increases with the increase of the initial concentration of COD_mnn at 25°C.As the reaction progresses,the adsorption rate gradually decreases until equilibrium.When the initial COD_mnn concentration was in the range of 4-8.4 mg/L,the adsorption capacity of the sediment from the Yellow River was compared with that of the sediment from the Yangtze River.The average adsorption of COD_mnn per unit of the Yellow River sediment was 1.61mg/g,and the sediment of the Yangtze River averaged 1.37 mg./g,showed that the sediment adsorption capacity of the Yellow River sediment was better than that of the Yangtze River sediment;compared the sediment adsorption sediment and suspended sediment adsorption of the Yellow River,when the initial COD_mnn concentration range was 4-At 8.4 mg/L,the time required for the adsorption equilibrium of the Yellow River's sediment and the Yellow River's suspension to reach the equilibrium state was 60 h and 24 h,respectively.Their unit adsorption capacities were 1.648 mg/g and 1.61 mg/g,respectively,indicating that the Yellow River's suspended material adsorption Ability was higher than sediment.The pseudo-second-order kinetics model can better describe the characteristic behavior of COD_mnn adsorbed by sediments and suspended substances in the Yellow River,and the correlation coefficient R² can reach above 0.9.?5?The adsorption behavior of COD_mnn by sedimentary sediments?sediments?and suspended sediments?suspended substances?of the Yellow River was more in line with the Langmuir isotherm model,indicating that the process belongs to monolayer adsorptionthe sediment of the Yellow River was adsorbing COD_mnn During the process,the average free energy of adsorption was less than 8,indicating that the adsorption process was mainly physical adsorption during the process of COD_mnn adsorption,the adsorption free energy change?G^?was less than 0,indicating that the adsorption process was spontaneous,and Spontaneity was higher than that of the Yangtze River sediment,?H^?was less than 0,indicating that the adsorption was an exothermic process,?S^?was greater than 0,indicating that the degree of chaos in the entire adsorption process was increased.?6?After the adsorption of saturated Yellow River sediments in slightly contaminated water with different initial COD_mnn concentrations was desorption in clean water:the greater the adsorption amount,the greater the desorption amount.As the reaction proceeds,the desorption rate gradually decreased,and the desorption occurs after about 48 hours.Balance,and the proportion of desorption of the Yellow River silt was slightly lower than that of the Yangtze River,indicated that the Yellow River sediment was more adsorbable than the Yangtze River sediment,which was due to the greater viscosity of the loess the pseudo-second order reaction kinetics to the Yellow River mud the sand desorption COD_mnn behavior had a better fitting effect,and the correlation coefficient R² can reach 0.99 or more.?7?There were a lot of microorganisms attached to the surface of the Yellow River sediment,which promoted the adsorption and degradation of COD_mn.It was one of the main ways of self-purification of water.The adsorption and degradation of COD_mnn by Yellow River suspension materials was better than that of the Yellow River sediment.Compared the adsorption and degradation laws of sedimentary sediments and suspended sediments in the Yellow River,when the initial COD_mnn concentration ranged from 4 to 9 mg/L,the dynamics of the sediment of the Yellow River was fitted to a secondary standard.The equilibrium adsorption value of the equation was 1.930 mg/g,the equilibrium adsorption value of the quasi-first-order equation was 1.863 mg/g,the equilibrium adsorption value of the quasi-second order equation of the suspended solid matter of the Yellow River was 2.446mg/g,and the equilibrium adsorption value of the quasi-first-order equation was 2.090.mg/g,which showed that the equilibrium adsorption value fitted by the kinetic quasi-secondary equation of the Yellow River sediment was slightly higher than the quasi-first-level fitting result,and the fitting effect of the Quasi-secondary equation was slightly better than that of the pseudo-level.?8?Adsorption and degradation of COD_mnn from the sediments of the Yellow River were increased by 16%with a pseudo first-order equation.Adsorption and degradation of suspended solids in the Yellow River resulted in a 26.8%increase in the removal rate of COD_mnn compared with adsorption.Adsorption and degradation of the adsorption time of adsorption to shorten the adsorption time than 1/4,indicating that the Yellow River sediment on COD_mnn degradation was also very obvious,but the degradation was less than the adsorption.?9?From the composition of microorganisms in the sediments of the Yellow River in the winter,there were three major microbial groups in the sediments of the Yellow River:the number of bacteria was the highest?85.56%?,followed by actinomycetes,and fungi were the least.Bacteria were the main of degradation of COD_mn.Investigate the distribution of microorganisms in sediments and suspended substances in the Yellow River:In the case of the same volume?per milliliter?,the average number of bacteria in the ecosystem of the Lanzhou section of the Yellow River from high to low was:Yellow River sediment>Yellow River Water Suspended Matter>Yellow River Water,indicated that under the same volume of water and surface sediment,the sediment provided more sites for microbial attachment because of its high density.In the same volume?per milliliter?of sediment and water,the bacterial content of the sediment of the Yellow River was higher than that of the suspended material in the Yellow River water,the bacterial content of the Yellow River sediment in the same sediment and suspended sediment was much lower than that of the suspension.It showed that the same dry weight of the Yellow River suspension material were more conducive to microbial adhesion than the 0-5cm Yellow River sediment,but the turbidity in the Yellow River water was lower in winter,and the amount of suspended material in the same volume space was less,and the sediment density was lower.Large and provide more places for microbial attachment.?10?Low temperature and low turbidity Yellow River water treatment was a problem.The responsesurfacemethodwasadoptedtooptimizetheeffectof coagulation-precipitation-filtration on the Yellow River summer normal temperature water and the winter low temperature and low turbidity water treatment results.The results showed that the coagulation-precipitation effluent after the sand filter treatment effect was better than the membrane filter,The effect of water filtration after coagulation was better than that of low-temperature and low-turbidity water,micro-flocculation?coagulation-filtration?was an enhanced filtration technology that immediately injects coagulation effluent into the filtration of the filter column,using the response.The surface method optimizes its optimal treatment effect on turbidity,CODmn,and ammonia nitrogen removal rate in low-temperature and low-turbid water in the Yellow River in winter.The results showed that compared with the coagulation-precipitation-filtration treatment technology,turbidity,permanganate index,ammonia nitrogen removal were increased 0.45,1.3,1.8 times...