Analysis of Nitrogen Removal Performance of Constructed Rapid Infiltration System (Cris)

Abstract

Abstract. The Constructed Rapid Infiltration System (CRIS) is widely applied for wastewater treatment. In China, however, fundamental research on functionality of CRIS is lacking. We used a CRIS simulation column to treat domestic sewage under experimental conditions, allowing determination of nitrogen pollutants removal performance. The obtained results showed that CRIS can effectively remove ammonia nitrogen with the average removal rate of 82.2% but results in a relatively low removal of total nitrogen (TN) with the average removal rate of 31.9%. The reason is that the system is frequently subjected to alternation of drying and wetting, which allows effective aeration. This leads to aerobic conditions, which is incompatible with the anaerobic requirements of denitrifying bacteria. In addition, these bacteria likely lack a suitable carbon source, as organic matter is effectively removed in the upper (aerobic) layer of CRIS. Lastly, the filter material used is generally negatively charged, thus repels nitrate, which prevents its retention and results in its discharge with the outflow. As a net result, the TN removal rate is low.

Effect of C/N Ratio on the Removal of Nitrogen and Microbial Characteristics in the Water Saturated Denitrifying Section of a Two-Stage Constructed Rapid Infiltration System

“…In addition, a dry-wet cycling of water feeding and draining is applied, which alternates the operation mode between an aerobic and (facultative) anaerobic environment, thus employing a more diverse mix of microorganisms. The unique operation mode and the rich diversity of microorganisms colonizing the filling medium of a CRI are favorable for efficient removal of pollutants from sewage [ 3 ].…”

Effect of Potassium Chlorate on the Treatment of Domestic Sewage by Achieving Shortcut Nitrification in a Constructed Rapid Infiltration System

“…Pictures of a practical example of a CRI system are shown in Figure 1 . The removal mechanism of the CRI system is to use the filling medium and microorganisms grown on the filling medium to adsorb, intercept, and decompose the pollutants in sewage [ 4 ]. Especially, since the CRI system has the unique structure and feeding mode, its filling medium has the aerobic, facultative, and anaerobic environment to grow abundant microorganism to allow for efficient sewage treatment [ 5 ].…”

Effect of Potassium Chlorate on the Treatment of Domestic Sewage by Achieving Shortcut Nitrification in Constructed Rapid Infiltration System

“…Sewage treatment technology for domestic sewage and polluted surface water treatment in small towns-Constructed rapid infiltration system (CRI) is a new sewage biofilm treatment technology put forwarded by professor Zhong zuoshen[1], due to it presents the both advantages of sewage rapid infiltration land treatment system and constructed wetland system, attracted increasing attention in recent years [2]. CRI system is mainly composed of feeding tank, grille, preliminary sedimentation tank, rapid infiltration tank and outlet system, adopts the dry-wet alternating operation mode and uses natural river sand, coal gangue, natural gravel, etc., to replace natural soil as filling medium to improve hydraulic load to 1.0-1.5m/d [3], the pictures of practical engineering of CRI system are shown in Fig.1.The removal mechanism of CRI system is to use the filling medium and microorganisms grown on the filing medium to adsorp, intercep and decompose the pollutants in sewage [4]. Especially, due to CRI system has the unique structure and feeding mode, its filling medium has the aerobic, facultative and anaerobic environment to grow abundant microorganism to make efficient sewage treatment [5].…”