Feasibility Study On The Removal Of Pollutants In Wastewater Using Construction Waste Brick As An Adsorbent

With the rapid development of economy and acceleration of urbanization, thenumber of construction waste increased dramatically. Arbitrarily stacking ofconstruction waste will not only the ecological environment, but also cause the wasteof resources. Currently, domestic and overseas have begun to pay great attention to theresource utilization of construction waste. Brick is one of the three basic buildingmaterials.In order to develop an efficient, readily available and economic adsorbent forpollution removal to prevent and control the increasingly serious water pollution, thispaper investigated the adsorption behavior of phosphate, ammonia nitrogen, methyleneblue and fluoride to construction waste brick in aqueous solutions, and analyzed theabsorption characteristics of the four pollutants. The results are as follows:(1) The results of dynamic analysis on the adsorption of phosphate toconstruction waste brick revealed that the adsorption equilibrium might take216hoursto reach, and the adsorption capacity could be2.10mg/g at20°C and1.10mg/g at4°C,respectively. Characteristics of adsorption could be best described by thepseudo-second-order model, and the behavior was fitted well with Langmuir isotherm.(2) The result of effect factors in20°C indicated that: when oscillation speedwas150rpm, and the wastewater pH was around2, the experiment could reach themaximum removal rate of83.90%. In the water system of the coexistence of fourinorganic anions, they all had no significant impact on the phosphorus removal, exceptHCO3-, it had greater inhibition on the adsorption of phosphorus onto constructionwaste brick. So construction waste brick in this study could be selective for adsorptionof phosphate in water bodies, and appropriate for phosphorus removal adsorbent. (3) In the conditions of20°C and4°C, the construction waste brick particlehad the adsorption capacity of0.07mg/g and0.05mg/g, and the removal efficiencieswere27.0%and21.9%respectively for the ammonia nitrogen concentration of10mg/L. It showed that construction waste brick in this study was not a kind ofexcellent performance of ammonia nitrogen adsorbent because of its low removal rate.(4) The results of the adsorption behavior of the different oscillation speed andinitial concentrations of fluoride in the water showed that, construction waste brickalmost had no effect on the removal of fluoride. Therefore, it was not suitable forfluoride removal.(5) Construction waste brick had the adsorption equilibrium time of72h, andthe removal rate of98.2%, when the methylene blue of10mg/L. Oscillation speed,initial pH and temperature had no significant effect on the adsorption. Characteristicsof adsorption could be best described by the pseudo-second-order model, and thebehavior was fitted well with Langmuir isotherm. By the comparison of the adsorptioneffect in different concentrations, it demonstrated that construction waste brick wasonly suitable for concentrations of200mg/L below of methylene blue wastewatertreatment.(6) Different origin of construction waste brick had very different removalefficiency of pollutants, such as ammonia nitrogen and phosphate. The results of thisstudy indicated that, the adsorption capacity of the pollutants on waste brick in Xi’anwas significantly smaller than in Fujian. Because waste brick in Xi’an was made byloess, while waste brick in Fujian was made by red soil. Therefore when theconstruction waste brick was used for wastewater treatment, such as strengthen thenutrient removal in constructed wetlands, should fully take into account the regionaldifference.