Hybrid zeolite-based ion-exchange and sulfur oxidizing denitrification for advanced slaughterhouse wastewater treatment

The discharge of slaughterhouse wastewater(SWW)is increasing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification(IX-AD)process was developed to advanced treat SWW after traditional secondary biological process.Compared with traditional sulfur oxidizing denitrification(SOD),this study found that IX-AD column showed:(1)stronger ability to resist NO_(3)^(-) pollution load,(2)lower SO_(4)^(2-) productivity,and(3)higher microbial diversity and richness.Liaoning zeolites addition guaranteed not only the standard discharge of NH_(4)^(+)-N,but also the denitrification performance and effluent TN.Especially,when the ahead secondary biological treatment process run at the ultra-high load,NO_(3)-N removal efficiency for IX-AD column was still~100%,whereas only 64.2%for control SOD column.The corresponding average effluent TN concentrations for IX-AD and SOD columns were 5.89 and 65.55 mg/L,respectively.Therefore,IX-AD is a promising technology for advanced SWW treatment and should be widely researched and popularized.

Waste heat recovery and denitrification of flue gases from gas-fired boilers

A waste heat recovery and denitrification system was developed for improving energy conservation and emissions control especially for control of PM2.5 particles and haze. The system uses enhanced heat and mass transfer techniques in a packed heat exchange tower with self-rotation and zero-pressure spraying, low temperature NO oxidation by ozone, and neutralization with an alkali solution. Operating data in a test project gave NOx in the exhaust flue gas of less than 30 mg/Nm3 with an ozone addition rate of 8 kg/h and spray water p H of 7.5–8, an average heat recovery of 3 MW, and an average heat supply of 7.2 MW.

Methane, Nitrous Oxide and Ammonia generation in full-scale swine wastewater purification facilities

The activated sludge process to remove nitrogen and biochemical oxygen demand （BOD） is reportedly cost-effective for swine wastewater treatment, and it use has thus increased in pig farming. Nitrous oxide （N20） is generated on farms as an intermediate product in nitrification and denitrification, and methane （CH4） is also generated from organic degradation under anaerobic conditions by microorganisms in manure or wastewater. This study was carried out at five activated sludge treatment facilities across Japan between August 2014 and January 2015. Measurements were conducted over several weeks at wastewater purification facilities for swine farms： two in Chiba prefecture （East Japan）, two in Okayama prefecture （West Japan）, and one in Saga （Southern Japan）. Taking several environmental fluctuations into account, we collected measurement data continuously day and night, during both high-temperature and low-temperature periods. The results indicated that CH4 and N20 emission factors were 0.91% （kgCHa·kg volatile solids^-1） and 2.87% （g N2O-N·kg total N^-1）, respectively. Ammonia emissions were negligible in all of the measurements from the wastewater facilities. The N20 emission factor calculated under this experiment was low compared to our previous finding （5.0%; g N2O-N·kg N^-1） in a laboratory experiment. In contrast, the CH4 emission factor calculated herein was rather high compared to the laboratory measurements. There was great variation in daily GHG emission factors measured in the actual wastewater treatment facilities. In particular, the N2O emission rate was affected by several environmental conditions at each facility location, as well as by the management of the wastewater treatment.