生猪养殖污水水质指标相关性分析与建模

    Correlation analysis and modeling of water quality indexes for swine breeding wastewater

    • 摘要: 生猪养殖污水成分复杂且对环境存在较大的污染风险,常规实验室监测法准确性高但效率低且时效性差,自动监测法速度快但成本高。为寻求一种能兼顾两种方法优点的监测方案,该研究以一家规模生猪养殖场的排放污水为研究对象,对衡量污水水质的7个主要指标的变化特征、相关性和其中2个指标的回归建模进行了研究。通过对不同季节及不同气候条件下30组随机样本的检测与相关性分析,发现氨氮、总氮和电导率有相似的变化趋势且彼此之间均存在强相关性,相关系数分别为0.772、0.775和0.920。基于相关性分析结果,对氨氮和总氮分别进行了一元和多元回归分析建模,并确定了相对最佳的适合于氨氮的"多项式回归模型"和总氮的"综合模型"。经验证,两个模型的决定系数分别为0.855和0.953,可较好地用于评价生猪养殖污水中氨氮和总氮2个指标的浓度大小。基于这2个模型,生猪养殖污水需直接检测的主要指标的数量可有效减少、检测难度和成本均明显降低。因此,模型可为生猪养殖污水高效、低成本的自动监测方案的建立提供重要的理论基础。

       

      Abstract: According to the difference of treatment process about swine breeding sewage, the treatment methods are divided into ecological treatment, industrial treatment and centralized treatment. The components of sewage treated by industrial treatment are extremely complex, there will be a great risk of environmental pollution if the sewage is directly discharged into the natural water body. It's very important to monitor sewage quality. The monitoring methods commonly used in swine breeding sewage mainly include laboratory monitoring and automatic monitoring. The laboratory monitoring is traditional, which has the advantage of high data accuracy and the disadvantages of low efficiency and poor timeliness, the sewage indexes can be detected fast but costly using automatic monitoring method. To find a monitoring scheme that combined the advantages of laboratory monitoring method and automatic monitoring method, took the sewage from a large-scale pig farm as the research object, the change characteristics, correlation of seven main indexes of sewage quality and regression modeling of two main indexes were studied. The seven indeices were respectively ammonia nitrogen, total phosphorus, total nitrogen, chemical oxygen demand, the potential of hydrogen, dissolved oxygen and electrical conductivity. Through the detection and correlation analysis of 30 random samples from different seasons and climatic conditions, it was found that ammonia nitrogen, total nitrogen and electrical conductivity had similar variation trends and strong correlation each other, the correlation coefficient of ammonia nitrogen and total nitrogen was 0.772, and that of ammonia nitrogen and electrical conductivity was 0.775, the correlation coefficient of total nitrogen and electrical conductivity was 0.920. Based on the results of correlation analysis, many types of monadic regressive and multivariate regression models for ammonia nitrogen and total nitrogen were established respectively, the relatively optimal "polynomial regression model" (model I) for ammonia nitrogen and the "comprehensive model" (model V) for total nitrogen were determined by comparing the coefficient of determination, residual sum of squares and the mean square regression of each model. The verification results based on 10 sets of data showed that the estimated values of these two models were closest to the measured values, the coefficients of determination of model I and model V were 0.855 and 0.953 respectively. Therefore, these two models could be used to evaluate the concentration of ammonia nitrogen and total nitrogen in swine breeding sewage. The existing studies shown that the data obtained by laboratory monitoring and automatic monitoring had the same change law although the value was different, which meant that there was a good linear relationship between them, hence a linear regression model based on the automatic monitoring data could be established to achieve the monitoring of water quality indexes accurately and rapidly. Based on this conclusion and the above two models, the feasibility of an efficient and low-cost automatic monitoring scheme for swine breeding wastewater quality was analyzed in this study. The indexes involved in the solution included electrical conductivity, the potential of hydrogen, ammonia nitrogen, total phosphorus, total nitrogen, and chemical oxygen demand, the total nitrogen that was difficult and expensive to detect automatically does not require to detect directly, the concentration of which could be calculated by the value of ammonia nitrogen and electrical conductivity according to model V, the concentration of ammonia nitrogen with relatively low difficulty and cost could be obtained by the value of electrical conductivity according to model I, the detection of electrical conductivity and potential of hydrogen was more convenient and the cost was lower, the data of total phosphorus and chemical oxygen demand would be obtained by linear regression model based on automatic monitoring data. Compared with the existing monitoring methods, the number of indexes that needed to be detected directly in this scheme would be significantly reduced, which would make the overall difficulty and the cost of monitoring decreasing, and the monitoring efficiency improved. Consequently, these two models could provide an important theoretical basis for the establishment of an efficient and low-cost automatic monitoring scheme for swine breeding sewage.

       

    /

    返回文章
    返回