Municipal sludge has economic value as a low-grade fertilizer as it consists of appreciable amounts of the macro and micronutrients. When using sludge as fertilizer, the economic aspect should be taken into account. In this study, the following specific objectives were identified: (a) to investigate the economic feasibility of using sludge as a fertilizer; (b) to estimate the maximum economic distance sludge can be transported as a fertilizer; and (c) to test the economic feasibility of selling sludge using commercial inorganic fertilizer as a bench mark. The study showed that for anaerobically digested, paddy dried, municipal sludge consisting of 3% N, 2% P, and 0.3% K the economic feasibility of transporting the sludge was limited to a diameter of 20 km in the arid zone, 28 km in the semi-arid zone, 51 km in the sub humid zone, 66 km in the humid zone, and 75 km in the super-humid zone. Therefore, the economic feasibility of using sludge as a substitute for or complementary to commercial inorganic fertilizer is dictated by the distance between the wastewater care work and the farm, sludge nutrient concentration, agro-ecological zone (rain and temperature), and the real-time commercial inorganic fertilizer price.

中文翻译：

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城市污泥作为低品位营养来源的成本效益分析：来自南非的案例研究

市政污泥作为低级肥料具有经济价值，因为它包含大量的宏量和微量营养素。使用污泥作为肥料时，应考虑经济方面。在这项研究中，确定了以下具体目标： (a) 调查使用污泥作为肥料的经济可行性；(b) 估算污泥可以作为肥料运输的最大经济距离；(c) 测试以商业无机肥料为基准出售污泥的经济可行性。研究表明，对于由 3% N、2% P 和 0.3% K 组成的厌氧消化、稻谷干燥的城市污泥，运输污泥的经济可行性仅限于干旱区 20 公里的直径，干旱区 28 公里。半干旱区，亚湿润区51公里，湿润区66公里，超湿润区75公里。因此，使用污泥替代或补充商业无机肥料的经济可行性取决于废水处理工作与农场之间的距离、污泥养分浓度、农业生态区（雨和温度）以及实际环境。时间商品无机肥价格。