Abstract: This paper describes the NiiMi process designed to treat landscape water. The main aim of the research was to investigate the feasibility of NiiMi for removing organic and nutriment materials from landscape water. During the batch-scale NiiMi operation, the removal rates of color ranged from 66.7%–80%, of turbidity from 31.7%–89.3%, of chemical oxygen demand (COD) from 7%–36.5%, of total phosphor (TP) from 43%–84.2%, of soluble phosphate from 42.9%–100%, of total nitrogen (TN) from 4.2%–46.7%, and of NH₄⁺-N from 39.3%–100% at the hydraulic loading of 0.2 m³/(m²·d). Results showed that the removal efficiencies of COD, TP, soluble phosphate and TN decreased with the decline in the temperature. The NiiMi process had a strong shock loading ability for the removal of the organics, turbidity, TP, soluble phosphate, TN and NH₄⁺-N. Three sodium chloride tracer studies were conducted, labeled as TS1, TS2, and TS3, respectively. The mean hydraulic retention times (mean HRTs) were 31 h and 28 h for TS1 and TS2, respectively, indicating the occurrence of a dead zone volume of 12% and 20% for TS1 and TS2, respectively. TS1 and TS2 displayed the occurrence of short-circuiting in the NiiMi system. The comparison results between TS1 and TS2 were further confirmed in the values obtained for some indicators, such as volumetric efficiency (e), short-circuiting (S), hydraulic efficiency (λ) and number of continuously stirred tank reactors (N).

Key words: NiiMi system, Landscape water, Purification efficiency, Hydraulic efficiency, Tracers

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