Study On 2-Chloro-Nicotinic Acid Simulated Wastewater Treatment With Induced Crystallization Method

2-chloro-nicotinic acid production process generates a large amount of waste water. It has high content of phosphorus and metal ions, such as Cu2+, causing serious pollution to the environment. Steel slag is the production of steel waste. It produces alkaline substances when dissolved in water. So it can be as seed in the induced crystallization.This experiment was divided into three parts, the first part is the research and analysis on the physicochemical properties of the crystal seed of steel slag, the results show that alkaline substances are soluble in water easily, they can be dissolved in water to reach equilibrium within three minutes, alkaline material in steel slag will be inhibited to continue dissolving in water when pH is close to 10.4, and ultimately the dynamic balance will achieve; In the second part, steel slag is chosen to be the crystal seed to research the impact on phosphorus removal efficiency in wastewater when in different stirring, slag dosage, initial concentration of phosphorus conditions, XRD, FT-IR, SEM techniques were used to analyze the struvite product seperated from the streams, the results show that agitation can promote stravite crystallization efficiency and phosphorus removal rate will be higher with the longer stirring time,40g/L is the best crystal seed dosage under the conditions of without pH value controlling, stirring speed of 180 rpm and continue stirring 21h.The third part is the simulated wastewater’s crystallization tests of 2-chloro-nicotinic acid, to determinate phosphorus removal rate under the same conditions, XRD, FT-IR, SEM techniques were used to analyze the struvite product seperated from the streams, the result show that the presence of Cu2+will reduce the efficiency of struvite crystallization. The reason may be that metal ions went into the crystal lattice as a paramagnetic material, became the center of orthogonal octahedral crystal, and thus affected the efficiency of struvite crystallization.The significance of this study is that:on the one hand, to reduce the occupation of steel slag to land resources, to avoid the waste of resources; On the other hand, the magnesium recovered by magnesium ammonium phosphate crystallization from phosphorus wastewater is a effective fertilizer, It can be used as slow-release fertilizer; And more importantly, the emissions of the phosphorus wastewater would cause pollution of natural water bodies and eutrophication. The treated wastewater can greatly reduce the probability of eutrophication because of its low phosphorus content.