Efficiency Of Urine Hydrolysis Pretreatment With Its Effect Evaluation And Risk Analysis For Vegetable Cultivation

Aiming at the current situation of inadequate collection and treatment of rural sewage and inadequate utilization of resources,a resource utilization experiment was performed for urine under the technology of source separation of fecal and urine to investigate the feasibility of using urine as fertilizer after collection.The pretreatment technology of urine used for plant cultivation was studied,and pakchoi and water spinach were selected,and hydroponic experiments and soil cultivation experiments were performed to evaluate the fertilizer efficiency and risk of different treatments after urine treatment.The test showed that there are abundant nutrients in urine,with a total nitrogen concentration of 9539 mg / L,a total phosphorus concentration of 477 mg / L,an ammonia nitrogen concentration of 1023 mg / L,a phosphate concentration of 417 mg / L,and a trace element content.The nutrients were abundant so that the urine had full potential as a fertilizer.Before being used as fertilizer,fresh urine needs to be pretreated.When no urease was added,the urine hydrolysis speed was the fastest at 30 ° C,and it took about 10 days to hydrolyze.When the amount of urease was 10 mg / L,the urine could be hydrolyzed within 2 days at 50 ° C.After hydrolysis,the physical and chemical properties of urine changed.The p H value increased from 6.4 to 9.18,the ammonia nitrogen concentration increased from 1023 mg / L to 7616 mg / L,and the phosphate concentration decreased from 417 mg / L to 376 mg / L.Through comprehensive consideration of economic cost and hydrolysis effect,50 ° C and 10 mg / L urease dosage were selected as suitable conditions for urine hydrolysis pretreatment.Secondly,the optimal dilution ratio of urine hydrolyzed fertilizer for hydroponic pakchoi and water spinach is 1:500,and the optimum addition amount for soil culture of pakchoi and water spinach is 10 m L/kg.In the hydroponic experiment,the average fresh weight of pakchoi at the end of the experiment was 9.45 g / plant,slightly lower than the 9.65 g / plant of the nutrient solution control group.And the average fresh weight of water spinach was 16.88 g / plant,which was higher than that of the nutrient solution control group(16.58 g / plant).The physical and chemical indicators of the solution in the hydroponic tank were tested,and it was found that the absorption and utilization of ammonia nitrogen by the two vegetables were better,showing the adaptability to fertilizers containing ammonia nitrogen as the main component.In soil cultivation experiments,the highest yield of vegetables was obtained with the use of urine hydrolyzed fertilizer and grass ash.Among them,pakchoi was 8.52 g / plant,which was higher than 8.06 g / plant in the chemical fertilizer control group,and water spinach was 11.29 g / plant,slightly higher than 11.26 g / plant in the fertilizer control group.The physical and chemical indicators of the soil were tested.The soil with the combined application of urine and plant ash has high organic matter content and high soil catalase activity,which makes the growth effect of the plants were the best.Therefore,the best way is the utilization of urine hydrolyzed fertilizer with plant ash.Finally,the absorption of externally added drugs(carbamazepine and ibuprofen)under the conditions of hydroponic culture and soil culture was also investigated to evaluate their ecological risks.Residues of carbamazepine and ibuprofen were detected in pakchoi and water spinach in the high-dose addition group(500 ?g and 1000 ?g),which was no more than 5 ?g/g.And the urine hydrolyzed fertilizer was used after dilution in actual use.The content of the medicines were extremely low,so it can be considered that the risk of drug exposure to urine hydrolyzed fertilizers is extremely low.To sum up,it is feasible that urine hydrolyzed fertilizers can be used for vegetable cultivation in both hydroponic and soil culture methods.