Study On Nitrosification Of Rich Ammonia Wastewater

This paper presents a new nitrogen removal process, which removes nitrogen by nitrification/denitrification with nitrite as intermediate. The critical factor is to prevent the formation of nitrate. Two questions are discussed: one is the effect of nitrosification inoculated with enriched culture fluid of ammonia oxidizers; another is the optimum condition of system operation.Experiment uses artificial wastewater which is sufficient in nitrogen and deficient in carbon, and adopts three reactors: Biological membrane reactors filled with elastic filler (Reactor (A), biological membrane reactors filled with RCB-5225J biological filler (Reactor (B)), and active sludge reactor. The effect of nitrosification is compared among these three reactors by sequencing batch, and the difference of Reactor (B) by sequencing batch and continuous influent is studied. This paper also discusses the effects of carbon source, heterotrophic bacteria, pH, temperature, free ammonia (FA), and aeration on nitrosifcation of the reactor.Experiment results show that active sludge reactor gives satisfying effect of nitrosification by using the enriched culture fluid of ammonia oxidizers as inoculating sludge, and ammonia removal velocity is 500mgN/(L·d) and the convert ratio of nitrite maintains the level above 80%, and effects of two membrane reactors are worse with low nitrite convert ratio below 68% and ammonia removal velocity below 134.95 mgN/(L·d). Adding a little of organic substance can contribute to the forming of zoogloea and improve the active sludge settleability, while it is no obvious effects on both biological membrane reactors. It is suitable condition for the active sludge reactor to perform efficiently to maintain the temperature of 16-30℃ and pH ranging from 7.6 to 8.3 with the optimum pH of 7.9. The system can work under a higher concentration of FA (170-200mg/L). Under the condition of increasing aeration, the treatment efficiency can be improved with the higher ammonia removal velocity of 1000mgN/(L·d).