Sharon-Anammox Process For Nitrogen Removal From Piggery Wastewater

Piggery wastewater, which is characterized by high concentration ofCOD,ammonium and suspend substance, has become a most important source ofnon-point source pollution and also severely threats drinking water security in ruralarea. How to discharge piggery wastewater with the ammonium concentrationmeeting standard by economical and effective method? This is the most urgentproblem in piggery wastewater treatment.As a new biological nitrogen removal technology, Anammox process has beenpaid more and more attention by researchers all over the world. Anammox hasadvantages of no need of organic carbon addition, low oxygen consumption andenergy consumption. Plenty of investigations have been carried out to the mechanism,physiological and biochemical characteristic of bacteria about Anammox. Most ofresearches focused on synthetic wastewater, there is rare report about its application inpiggery wastewater.In this paper, experimental studies were performed to investigate Sharon processin treatment of piggery wastewater, the start up process of Annammox usingsynthetic wastewater were studied, the feasibility of applying Sharon-Anammoxprocess in the nitrogen removal of piggery wastewater was evaluated.1. Sharon process of piggery wastewater was firstly investigated to analyze theeffects of water quality and main running parameters, which meet the NH₄⁺-N toNO₂^--N ratio requirement of successive Anammox. Results showed: (1)During SharonProcess, after 8～10 hours' reaction the NH₄⁺-N to NO₂^--N ratio in effluent reached1:1.0～1:1.23, when the removal percentage of NH₄⁺-N was 58.3～65.6%, a semi-nitration rate of above 97% was achieved during the process; meanwhile 59.2～68.6% of the COD was also removed. (2)The aeration rate (oxygen) had obviouseffect on the hydraulic retention time(Ï„) which met the NH₄⁺-N to NO₂^--N ratiorequirement of Anammox. As aeration rate increased, the hydraulic retention time(Ï„)was shortened. (3) The pH corresponding toÏ„was between 7.8 and 8.1, thus itneeded no artificial adjustment. (4) The reduction of ammonia and COD followed thefirst-order reaction kinetics. The velocity constants of ammonia and COD were0.0656～0.0724 l/h and 0.0491～0.0664 l/h, respectively.2. The startup of Anammox process using the artificial wastewater wasperformed simultaneously with Sharon. The aim was to investigate the runningparameters of Anammox and make foundation for the combination stage. By using themixture of denitrifying sludge and anaerobic sludge in tank of the breeding factory,sludge of Anammox activity was cultivated in UASB after 100 days. The removalpercentage of NH₄⁺-N and NO₂^--N were up to 48% and 41.5%, respectively, when theNH₄⁺-N and NO₂^--N influent concentration were 223.8mg/L and 171.4mg/L,respectively, the NH₄⁺-N and NO₂^--N removal rate was 1.33:1.3. After investigation of Sharon and startup of Anammox, effluent of Sharonprocess was added into the synthetic wastewater to combine Sharon and Anammoxstep by step. It took some time after the addition of Sharon effluent that Anammoxreaction continued and the removal rate kept increasing. It indicated that nitrifyingbacteria were carried by the Sharon effluent cumulated in the outer layer of Anammox.This enhanced transfer resistance of Anammox reaction and the increasing removalrate was restrained.4. In the bio-contact oxidation pond of practical project, Sharon process werecarried out successfully and organic compounds were removed effectively. Anaverage NO₂-N/NH₄⁺-N rate of 1:1.0 was achieved in the effluent, which met therequirement of successive Anammox. Under condition of suitable influentconcentration and temperature, there was evidence that Anammox could start up inABR. The variety of wastewater and temperature had great affects on Anammox activity in practical engineering.Innovation of this paper: (1) The Sharon process for treating piggery wastewaterwas discussed in details. Technological parameters that met requirement of Anammoxwere obtained. The dynamic models of COD and ammonium removal in the processwere educed. (2) Sharon-Ananmmox for treatment of piggery wastewater wasinvestigated, and the primary influencing factors was studied.This paper could be a theoretical consult for research of Anammox utility.