马铃薯淀粉加工废水还田利用对土壤养分及重金属的影响

为了研究马铃薯淀粉加工废水还田利用对农田土壤养分及重金属的影响，选取宁夏固原市6家马铃薯淀粉生产企业，分别采集施用与未施用马铃薯淀粉加工废水的农田土壤样品，通过配对样本t检验和综合指数评价分析土壤养分及土壤重金属含量的变化。结果表明：农田土壤各项重金属指标配对样本t检验结果P>0.05，表明施用与未施用马铃薯淀粉加工废水的各企业农田土壤中各项重金属含量无显著差异；各企业土壤环境综合指数配对样本t检验结果P>0.05，表明施用马铃薯淀粉加工废水的农田土壤整体环境质量与未施用的相比无显著差异，与土壤各项重金属配对样本t检验分析结论相互印证。土壤养分配对样本t检验结果P<0.05，施用马铃薯淀粉加工废水的农田土壤各项养分含量显著提高，参考北京市土壤养分分等定级标准的综合指数评价法分析，农田土壤养分由未施用马铃薯淀粉加工废水时的中级（土壤养分综合指数I=53）水平提升到施用后的高级（I=83）水平。研究表明，马铃薯淀粉加工废水还田利用在增加土壤肥力的同时不会造成农田土壤重金属含量的显著变化。

Effect of returning potato starch processing wastewater on nutrients and heavy metals in soils

In order to study the effects of potato starch processing wastewater on nutrients and heavy metals in soils, we selected six potato starch production enterprises in Guyuan City, Ningxia and measured soil nutrients and heavy metals on farmlands irrigated with potato starch wastewater from commercial processing companies. Paired t-tests and comprehensive index evaluations were used to test changes in soil nutrients and heavy metals in farmland soil samples with and without irrigation using potato starch processing wastewater. No significant difference in heavy metals was observed between the two treatments (P>0.05). We also found no significant differences using comprehensive index evaluation, indicating no significant differences between treatments regarding soil quality, as confirmed by the previous analysis. Moreover, soil nutrient content was significantly improved on farmlands irrigated with potato starch processing wastewater (P<0.05). The comprehensive index (I) evaluation method of the grading standard also indicated significantly increased soil nutrients on farmland with potato starch processing wastewater irrigation (I=83) when compared with soils that did not receive wastewater irrigation (intermediate level, I=53). Therefore, our results suggest that irrigation with potato starch processing wastewater increases soil fertility without significantly increasing soil heavy metal content.