Various additives were evaluated to assess their ability to prevent ash agglomeration during the gasification of high-sodium lignite. Additives that showed promise in simple muffle furnace tests included meta-kaolin, vermiculite, two types of silica fume, and one type of bauxite. Additives that were tested and rejected included dolomite, calcite, sand flour, kaolinite, fine kaolin, and calcined bauxite. Based on the muffle furnace test results, the meta-kaolin was selected for a follow-on demonstration in a pilot-scale coal gasifier. Pilot-scale testing showed that the addition of coarse (minus 14-mesh, 920-μm mean size) meta-kaolin at a feed rate roughly equivalent to the ash content of the lignite (∼10 wt %) successfully prevented agglomeration and deposition problems during gasification of high-sodium lignite at a maximum operating temperature of 927 °C (1700 °F).

In this study, pilot-scale tests were conducted to evaluate the effect of volumetric mixing ratio of landfill leachate to sewage on the performance of the combined ammonia stripping and reversed anaerobic/anoxic/oxic (A(2)/O) process for co-treatment of landfill leachate and municipal sewage. Stripping, as pre-treatment, could significantly remove ammonia nitrogen (NH3-N) and total nitrogen (TN) by 55% and 52%, respectively. Moreover, chemical oxygen demand (COD) was slightly reduced by 6.8%, and little total phosphorus (TP) was removed. The subsequent reversed A(2)/O process appeared to be highly influenced by the volumetric mixing ratio of leachate to sewage. Typically, the effluent COD, NH3-N, TN and TP increased with the increasing ratio from 1:30 to 1:15, namely, the increasing fraction of leachate. Over the all tested mixing ratio range, the effluent COD and NH3-N were satisfied with the primary B standards of Chinese Discharge Standard of Pollutants for municipal waste water treatment plant (GB18918-2002). The standards different from the primary A standards for water reuse are used for discharge into the most surface water bodies in China. However, TN and TP would exceed the primary B standard levels at a mixing ratio of 1:15 or greater. These findings suggest that an appropriate volumetric mixing ratio should be carefully selected to ensure the performance of the reversed A(2)/O process.

Enhance chemical coagulation for coking wastewater was employed as advanced treatment method for A/O biological effluent in this paper. Factors such as solution pH and coagulant dosage that influence the process of coagulation were experimentally tested. The index of A/O biological treatment of coking wastewater was: COD Cr value was 367mg/L, Turbidity was 44 UNT and Chroma was 75. Results showed that during pH value 4～10 range and the same dosage of coagulation process, turbidity, chroma and COD Cr removal rate of A/O biological effluent of coking wastewater were the best when pH=6. The optimum dosage coagulant is 10mg/L when the pH = 6, this dosage is the best for removal rate of chroma, turbidity and COD Cr . The removal rate of chroma, turbidity and COD Cr is respectively 66.67%, 50% and 68%.The A/O biological effluent of coking wastewater meets the national emission standards finally.