Development Of Coagulation And Scale Control Agent And Its Simultaneous Turbidity And Scale Inhibition Efficiency Research

Due to geological features and water source structure and other reasons,although drinking water in some areas of China to meet the drinking standards,but there is a general situation of high hardness and alkalinity.Combined with the tradition that our residents are used to drinking boiling water,this kind of water is prone to the problem of boiling water scale,which is also the main reason why users question the safety of water quality.Existing scale control process from the perspective of the principle of action can be divided into softening process to remove calcium and magnesium and other hardness factors in water and control the alkalinity factor in water acid-base balance aeration process.The softening process controls scale generation by removing calcium and magnesium hardness,while the acid-base balanced aeration process inhibits scale generation by reducing the alkalinity in water.Acid-base balanced aeration process has the advantages of economic efficiency,and can effectively retain the beneficial native calcium and magnesium ions in the water,but the process is currently mainly for the conventional water treatment process discharge water for subsequent scale control research applications,extending the water treatment process and reaction time,limiting the application of the process.In this study,we developed a coagulation and scale control agent（PCH）with simultaneous turbidity and scale inhibition efficiency by coupling polymeric aluminum chloride（PACl）,chitosan（CTS）and hydrochloric acid（HCl）to the existing problems of acid-base balanced aeration process and conventional water treatment process in water treatment plants.By studying the coagulation experiments under different substrate conditions,the effects of PACl,CTS and acidification degree on the turbidity and scale inhibition efficiency and action mechanism of PCH were clarified,and the coagulation behavior and advantageous interval of PCH treating raw water of different substrates were investigated;the action mechanism of simultaneous turbidity and scale inhibition efficiency of PCH was clarified by three-dimensional fluorescence spectroscopy,parallel factor analysis,floc characteristics analysis and scale control mechanism analysis;the PCH was used in The group developed an intensive turbidity and scale removal equipment to verify the effect of large-scale field operation and evaluate the turbidity and scale inhibition efficiency,long-term operational stability and mitigation effect of PCH on ultrafiltration membrane contamination.The results of this paper are summarized as follows:（1）PACl and CTS were compounded,acidified and stabilized to obtain coagulation and scale control agent（PCH）and characterized.The results showed that most of the absorption peaks of PCH were consistent with PACl,and some of the characteristic peaks changed significantly;the Al_c content was basically the same as PACl,and the Al_a content increased and Al_b decreased.The changes in the distribution of both functional groups and Al forms indicate that the preparation of PCH is not a simple physical mixture,but a chemical interaction,forming a new water treatment agent with both turbidity and scale inhibition efficiency.The results show that CTS can significantly enhance the coagulation effect.When the ratio of CTS is low,PCH mainly plays the role of electro-neutralization,while when the ratio of CTS is high,PCH mainly plays the role of electro-neutralization and adsorption bridging.At the same time,the alkalinity of raw water is reduced through H⁺in PCH to meet the target alkalinity without obvious scale particles after boiling,thereby inhibiting the formation of scale,and has a very wide range of applications.（2）The 3DEEM-FRI technique was used to analyze the effectiveness of PCH in removing different organic pollutant types.Parallel factor analysis showed that the main fluorescent fractions in the water samples were fulvic acid-like,humic acid-like and amino acid-like substances,respectively.The results showed that PCH could effectively remove humic acid-like and fulvic acid-like substances,and also had significant effect on the removal of amino acid-like substances.Compared with hydrochloric acid and PACl separately,the flocs formed by PCH were larger in size and looser in structure,and had stronger shear resistance and recovery regeneration ability;the flocs formed by PCH were smaller in size than PACl alone,which was caused by the introduction of H⁺acidification and scale inhibition.（3）The field operation shows that PCH has significant simultaneous turbidity and scale inhibition efficiency and good operational stability.Compared with acidified coagulation,it significantly improves the removal rate of each target substance by the intensive turbidity and scale removal equipment and effectively alleviates the ultrafiltration membrane contamination.During continuous operation,the water quality indicators such as turbidity,UV₂₅₄,DOC,alkalinity and post-boiling turbidity are stable,and the pH of the water body is stable to above 7 after the equipment aeration unit,meeting the water quality standard requirements.