Abstract
Contrary to the constraints in time, investment, and management of the traditional technology for waste water treatment, this paper seeks to propose a more advanced, reliable, and affordable new technology to restore urban polluted rivers to pristine quality levels. The paper also presents new ideas on the selection and use of microbial agents to improve the efficiency of pollution removal. It presents the successful implementation of microbial technology (MT) on Chengnan River, which was heavily polluted before MT implementation. Without artificial aeration, sediment dredging, or complete sewage interception, we directly sprayed a previously configured HP-RPe-3 Microbial Agent into the water body and sediment. We considered the feasibility of MT for treating polluted urban rivers from the perspective of several water quality indices evaluation methods. After the treatment, the concentration of dissolved oxygen (DO) reached 5.0 mg/L, the removal rates of ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) reached 20% and 38% respectively, and the average degradation rate of total phosphorus (TP) along river was close to 15%. Also, the Nemerow Index of the river was reduced from 2.7 to 1.9. The Fuzzy Comprehensive Index shows a tendency for improvement from Inferior Grade V to a better grade (approximately Grade III). The color of the river water changed, from black or dark green, to its original color. The results indicate that the bioremediation technology of directly adding microbial agents mainly aimed for the degradation of NH3-N can preliminarily eliminate the black-odor phenomenon of urban rivers, and improve their water quality. It is expected that the MT application, and the concept of how to select the corresponding microbial agents according to main pollutants, can be widely accepted and applied to similar cases.
Highlights
According to the United Nations Educational Scientific and Cultural Organization (UNESCO), water covers 72% of the earth surface; freshwater only accounts for 0.5% of all the water resources [1]
The pollutant removal rate was determined by the average concentrations of the major water quality parameters before and after the microbial treatment, which can be calculated by the following equation: (C0 − C )
Based on the Nemerow pollution index method and standard of classification, this part evaluates the comprehensive effects of the microbial technology on the river odor, from 15th April to 2nd May, and screens out major pollutants
Summary
According to the United Nations Educational Scientific and Cultural Organization (UNESCO), water covers 72% of the earth surface; freshwater only accounts for 0.5% of all the water resources [1]. With the global population explosion and rapid economic development, the demand for industrial water, agricultural water, and domestic water has increased rapidly, and the shortage of fresh water is becoming more and more serious [5,6]. The deterioration of water quality is exacerbating the shortage of water resources. Quality-induced water shortages have recently been a matter of great concern at local, regional, and global levels, especially in developing countries [5,7,8]. Water resources protection and rational utilization, and the efficient restoration of polluted water, have become majors focuses of the world
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