scholarly journals Improving total nitrogen removal using a neural network ammonia-based aeration control in activated sludge process

Author(s):  
M. H. Husin ◽  
M. F. Rahmat ◽  
N. A. Wahab ◽  
M. F. M. Sabri
1996 ◽  
Vol 34 (1-2) ◽  
pp. 459-466 ◽  
Author(s):  
Shigeo Fujii

The nitrogen removal efficiency of the step-feed anoxic-oxic activated sludge process, which has two anoxic tanks and two oxic tanks, was theoretically discussed on the basis of the stoichiometry of denitrification and nitrification reactions. As the first step, effluent NH4-N and NO3-N concentrations were formulated with four parameters; 1) a, equivalent ratio of alkalinity to ammonia in influent, 2) b, that of substrate to ammonia, 3) r, step ratio of influent to the second anoxic tank and 4) R, return (+ recycle) sludge ratio. This calculus was done for the possible sixteen (=24) cases which show different reaction patterns in four tanks, and 12 cases out of 16 were found to be available. The effects of step ratio, r were examined in its range of 0 - 1 at a fixed R value, and it was found that the increase of r alters the outcome in a different way depending on the ranges of a and b. Consequently, zoning of a-b coordinates was successfully made, and the optimal r value for maximum total nitrogen removal was obtained in each zone. In addition, the optimal volume allocation of the four tanks was discussed and the ratios were formulated for each zone.


1992 ◽  
Vol 25 (4-5) ◽  
pp. 203-209 ◽  
Author(s):  
R. Kayser ◽  
G. Stobbe ◽  
M. Werner

At Wolfsburg for a load of 100,000 p.e., the step-feed activated sludge process for nitrogen removal is successfully in operation. Due to the high denitrification potential (BOD:TKN = 5:1) the effluent total nitrogen content can be kept below 10 mg l−1 N; furthermore by some enhanced biological phosphate removal about 80% phosphorus may be removed without any chemicals.


2005 ◽  
Vol 40 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Yong-Woo Hwang ◽  
Chang-Gyun Kim ◽  
In-Jun Choo

Abstract This study was conducted to assess the possibility of simultaneous nitrification and denitrification in an activated sludge using a cilia media packed with granular sulfur in a single reactor. For the granular sulfur column adopted, the total nitrogen removal was up to 67%. This facilitated the simultaneous decomposition of autotrophic and heterotrophic denitrifiers present at a 5:2 ratio. On the other hand, the control incubation test employing glass beads achieved only 18% denitrification. Regardless of the NH4-N loadings, the use of ciliated granular sulfur columns, made denitrification 1.5 times faster than when cilia was not used. The size of the granular sulfur columns directly contributed to the extent of denitrification, which was correlated to the void sphere of anoxic zones through the columns. Dissolved oxygen (DO) concentrations lower than 4.0 mg/L did not influence the level of denitrification. However, when higher than 4.0 mg/L, the DO began to negatively impact the denitrification rate. The study found that the simple installation of a cilia media packed with granular sulfur in an existing activated sludge could simultaneously achieve an efficient nitrification/denitrification in a single reactor.


1998 ◽  
Vol 38 (1) ◽  
pp. 63-70 ◽  
Author(s):  
H. J. Kiuru ◽  
J. A. Rautiainen

The Laboratory of Environmental Engineering at the Helsinki University of Technology (HUT) carried out in 1991-1995 two successive full-scale research and development projects at the Pihlajaniemi WWTP of Savonlinna concerning biological nutrient removal from municipal wastewater. The projects have resulted in two reports in Finnish with quite large English summaries. This WWTP was constructed originally (1978) as a conventional low-loaded activated sludge plant with the simultaneous precipitation of phosphorus. It was dimensioned for a sludge concentration of 3.5 kgMLSS/m3 in the aeration tanks. Six years later (1984) the plant was fitted with a tertiary stage of flotation filters in order to improve the removal of suspended solids and phosphorus. Nitrification was introduced to the activated sludge process of the plant in 1987. It could be done without any extension by using the sludge concentrations of 6-10 kgMLSS/m3 in the aeration tanks. In that way, this activated sludge process was converted into a very low-loaded one. The process became able to nitrify totally in the circumstances in which the wastewater temperature varies at the range of 4-20°C. The actual hydraulic as well as the BOD7-load of the plant are about 40% of the original dimensioned ones. This activated sludge process of the Pihlajaniemi WWTP was modified in 1991-1993 for nitrogen removal and then in 1994-1995 for both biological phosphorus and nitrogen removal Denitrification was introduced to the process and the simultaneous precipitation of phosphorus in that was replaced by biological phosphorus removal still without any extension of the activated sludge process. The plant has now been operated over four years with biological nutrient removal exploiting the organic carbon compounds of the wastewater. A very little addition of some precipitant is used to improve the biological removal of phosphorus. The chemical and energy cost of the plant has been reduced by some 50% due to the introduction of biological nutrient removal. The BOD7-value of the treated wastewater is mainly less than 3 mg/l (always less than 5 mg/l). The content of total phosphorus in the treated wastewater is usually less than 0.3 mg/l (always less than 0.5 mg/l). The content of total nitrogen in the treated wastewater is mainly 8-12 mg/l. Reductions for BOD7 and total phosphorus over 95% as well as that for total nitrogen about 70% are achieved.


2001 ◽  
Vol 44 (4) ◽  
pp. 279-286 ◽  
Author(s):  
S. Villaverde ◽  
M. L. Lacalle ◽  
P. A. García-Encina ◽  
F. Fdz-Polanco

A conventional activated sludge reactor operated with short cycled aeration was used for total nitrogen removal of UASB anaerobic reactor effluent containing nitrogen (up to 1,200 mg NKT/L) and organic matter (up to 2,000 mg COD/L). Initially the reactor was fed with synthetic water to progressively introduce the UASB effluent. This favored the acclimation of the microorganisms to the real environment. The results obtained throughout this study showed that initially the tested technology is feasible and can report significant cuts on operation and maintenance when compared to conventional activated sludge processes. Total nitrogen removal up to 66% was attained treating the effluent of an UASB process designed for treating the wastewater of a potato starch factory. Total nitrogen removal capacities ranging between 0.1 and 0.58 kg of nitrogen per cubic metre per day are reported. Short-cycled aeration allowed for a more efficient use of the oxygen supply for nitrification and the organic carbon content present in the wastewater for denitrification. This operating protocol has demonstrated serious advantages in terms of operation costs and simplicity when total nitrogen removal is wanted. Most of the existing activated sludge processes, i.e. single continuous flow reactors, can be updated for total nitrogen removal essentially at no cost, the inversion (aeration control system) is rapidly returned as reduction in energy expenditure.


2014 ◽  
Vol 69 (7) ◽  
pp. 1558-1564 ◽  
Author(s):  
Yeong-Nan Chao ◽  
Jui-Hsien Lin ◽  
Kok-Kwang Ng ◽  
Chung-Hsin Wu ◽  
Pui-Kwan Andy Hong ◽  
...  

This study presented a method to upgrade existing aeration tanks to remove total nitrogen (TN). Bioplates carrying entrapped biomass were installed in an aeration basin to create anoxic/anaerobic zones where denitrification can proceed. In a reactor that coupled bioplates containing entrapped biomass (equivalent to as high as 7,500 mg/L of biomass) and an activated sludge suspension (at mixed liquor suspended solids of 1,300–2,400 mg/L), nitrification efficiency exceeded 95% for an influent wastewater containing 21–54 mg/L of NH3-N. In all cases amended with alkalinity and with or without added methanol as an electron source, TN removal was between 60 and 70%. The results demonstrated anoxic/oxic or anaerobic/anoxic/oxic processes could be incorporated in a conventional aeration basin, requiring no substantial modifications of the vessel and operation, and thus providing improved treatment in terms of nitrogen removal in the conventional suspended-growth process.


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