An autotrophic nitrogen removal process:Short-cut nitrification combined with ANAMMOX for treating diluted effluent from an UASB reactor fed by landfill leachate

A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.

Ammonia and phosphorus removal from using cash crop waste-derived agricultural runoff biochars

Adsorption of biochars(BC)produced from cash crop residuals is an economical and practical technology for removing nutrients from agricultural runoff.In this study,B C made of orange tree trunks and tea tree twigs from the Laoguanhe Basin were produced and modified by aluminum chloride(Al-modified)and ferric sulfate solutions(Fe-modified)under various pyrolysis temperatures(200℃-600℃)and residence times(2-5 h).All produced and modified B C were further analyzed for their abilities to adsorb ammonia and phosphorus with initial concentrations of 10-40 mg/L and 4-12 mg/L,respectively.Fe-modified Tea Tree B C 2h/400℃showed the highest phosphorus adsorption capacity of 0.56 mg/g.Al-modified Orange Tree B C 3h/500℃showed the best performance for ammonia removal with an adsorption capacity of 1.72 mg/g.FTIR characterization showed that P=O bonds were formed after the adsoiption of phosphorus by modified BC,N-H bonds were formed after ammonia adsorption.X P S analysis revealed that the key process of ammonia adsorption was the ion exchange between K+and N H 44.Phosphorus adsorption was related to oxidation and interaction between PO43-and Fe3+.According to X R D results,ammonia was found in the form of potassium amide,while phosphorus was found in the form of iron hydrogen phosphates.The sorption isotherms showed that the Freundlich equation fits better for phosphorus adsorption,while the Langmuir equation fits better for ammonia adsorption.The simulated runoff infiltration experiment showed that 97.3%of ammonia was removed by Al-modified Orange tree B C 3h/500℃,and 92.9%of phosphorus was removed by Fe-modified Tea tree B C 2h/400℃.