Evaluation of an anaerobic/aerobic system for carbon and nitrogen removal in slaughterhouse wastewater

2001 ◽  
Vol 44 (4) ◽  
pp. 271-277 ◽  
Author(s):  
L. A. Núñez ◽  
B. Martínez

In this work the performance of an anaerobic UASB reactor coupled with an activated sludge reactor for carbon and nitrogen removal in slaughterhouse wastewater is investigated. Periods with and without recirculation of aerobic effluent over 165 days are analysed. Working with a recirculation ratio of 2, removal efficiencies up to 90% and 65% are obtained for DQO and total nitrogen (TN), respectively. Higher recirculation ratios caused severe washout of active biomass in both reactors due to the high hydraulic loading rates applied. Denitrification in the UASB reactor was complete, with no nitrite accumulation and mainly to nitrogen gas. Significant decreases in COD removal efficiencies in the UASB reactor were observed at recirculation ratio of 2. Sudden decreases in total nitrogen efficiencies were related to inhibition process of nitrifying microorganisms, especially at high recirculation ratios.

2001 ◽  
Vol 44 (4) ◽  
pp. 145-150 ◽  
Author(s):  
E. Barrandeguy ◽  
S. Tarlera

Sterols (e.g. cholesterol) present in wool scouring effluent represent the most recalcitrant fraction in anaerobic treatment. This study was conducted to examine the feasibility of removal of this organic load through a denitrifying post-treatment stage. A stable cholesterol-denitrifying enrichment (CHOL-1) was obtained from sludge of a bench-scale upflow sludge bed (USB) denitrifying reactor integrated to a carbon and nitrogen removal system for sanitary landfill leachate. According to the amounts of cholesterol degraded and of nitrite and nitrogen gas formed, the capacity for complete cholesterol oxidation under anaerobic conditions by CHOL-1 can be assumed. Nitrite accumulation observed at a low C/N ratio outlines the importance of determining the optimal C/N ratio for adequate denitrifying reactor performance. The enrichment was partly identified with molecular analysis of cloned 16S rDNA sequences revealing the presence of two groups of bacteria belonging to the β subclass of the Proteobacteria. According to analysis of sequences, it can be inferred that a yet uncultivated new bacterium is the one responsible for cholesterol oxidation. Results of this study suggest that sludge from a denitrifying reactor treating leachate is potentially useful in a combined anaerobic-anoxic system for degradation of cholesterol that remains after methanogenic treatment.


2018 ◽  
Vol 77 (11) ◽  
pp. 2635-2641 ◽  
Author(s):  
R. K. X. Bastos ◽  
E. N. Rios ◽  
I. A. Sánchez

Abstract A set of experiments were conducted in Brazil in a pilot-scale waste stabilization pond (WSP) system (a four-maturation-pond series) treating an upflow anaerobic sludge blanket (UASB) reactor effluent. Over a year and a half the pond series was monitored under two flow rate conditions, hence also different hydraulic retention times and surface loading rates. On-site and laboratory trials were carried out to assess: (i) ammonia losses by volatilization using acrylic capture chambers placed at the surface of the ponds; (ii) organic nitrogen sedimentation rates using metal buckets placed at the bottom of the ponds for collecting settled particulate matter; (iii) nitrogen removal by algal uptake based on the nitrogen content of the suspended particulate matter in samples from the ponds' water column. In addition, nitrification and denitrification rates were measured in laboratory-based experiments using pond water and sediment samples. The pond system achieved high nitrogen removal (69% total nitrogen and 92% ammonia removal). The average total nitrogen removal rates varied from 10,098 to 3,849 g N/ha·d in the first and the last ponds, respectively, with the following fractions associated with the various removal pathways: (i) 23.5–45.6% sedimentation of organic nitrogen; (ii) 13.1–27.8% algal uptake; (iii) 1.2–3.1% ammonia volatilization; and (iv) 0.15–0.34% nitrification-denitrification.


2003 ◽  
Vol 48 (1) ◽  
pp. 207-214 ◽  
Author(s):  
A. Goltara ◽  
J. Martinez ◽  
R. Mendez

A 3.5 L Membrane Sequencing Batch Reactor (MSBR) was used for the treatment of a wastewater coming from the beamhouse section of a tannery. The wastewater, produced after the oxidation of sulphide compounds, contained average COD and ammonium concentrations of 550 and 90 mg/L respectively. The system was operated for a period of 150 days, with no sludge removal during the whole period of operation. The biomass concentration inside the reactor varied considerably, with maximum values close to 10 g/L at the end of operation. Low biomass yield values were achieved probably due to the low feed/microorganisms (F/M) ratio. An important accumulation of organic matter in the reactor was noticed, although the COD effluent was not affected due to the permeation through the membrane. The nature of this organic matter is finally discussed. Removal efficiencies close to 100% in ammonium and 90% in COD were achieved and the TN removal efficiency ranged from 60 to 90%.


2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Davood Nourmohammadi ◽  
Mir-Bager Esmaeeli ◽  
Hossein Akbarian ◽  
Mohammad Ghasemian

During the last decade, more stringent effluent requirements concerning the nutrients effluent values have been imposed by legislation and social concern. In this study, efficiency of total nitrogen removal in activated sludge and trickling filter processes (AS/TF) was investigated in Tehran North wastewater treatment plant. Biological system in this site was included, anoxic selector tank, aeration tank, final sedimentation, and trickling filter. A part of treated wastewater before chlorination was mixed with supernatant of dewatered sludge and fed to the trickling filter. Supernatant of dewatered sludge with high concentration of NH4-N was diluted by treated wastewater to provide complete nitrification in trickling filter Produced nitrate in trickling filter was arrived to the anoxic tank and converted to nitrogen gas by denitrification. According to the study result, low concentration of organic carbone and high concentration of NH4-N led to nitrification in TF, then nitrate denitrification to nitrogen gas occurred in selector area. NH4-N concentration decreased from 26.8 mg/L to 0.29 mg/L in TF, and NO3-N concentration increased from 8.8 mg/L to 27 mg/L in TF. Consequently, the total nitrogen decreased approximately to 50% in biological process. This efficiency has been observed in returned flow around 24% from final sedimentation into TF. It was concluded that, in comparison with biological nutrient removal processes, this process is very efficient and simple.


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.


2013 ◽  
Vol 67 (10) ◽  
pp. 2241-2248 ◽  
Author(s):  
Fernando Augusto Lopes de Assunção ◽  
Marcos von Sperling

This paper presents an evaluation of the influence of pH and temperature on nitrogen removal in a series of three shallow maturation ponds serving as post-treatment of upflow anaerobic sludge blanket (UASB) reactor effluent (approximately 200 population equivalent). Monitoring was from January 2007 to May 2009. Throughout this period, the ponds maintained relatively stable operational conditions in terms of depth and hydraulic retention time, thus enabling the evaluation of the influence of variations in temperature and pH on the performance in terms of nitrogen removal. In general, as expected, the removal of nitrogen was more effective when the temperature and pH of the ponds were higher, implying that these variables are relevant in the removal of nitrogen. Due to the fact that these parameters are included in the prediction equations for effluent ammonia and total nitrogen found in traditional models from the literature, fitting of the models to the experimental data was investigated. The models gave acceptable fittings in the estimation of effluent concentrations of ammonia and total nitrogen from maturation ponds treating UASB reactor effluent.


2014 ◽  
Vol 1030-1032 ◽  
pp. 422-425
Author(s):  
Er Long Jiao ◽  
Chun Di Gao ◽  
Hao Li ◽  
Wei Xiao Wang ◽  
Shi Xin Fan

The effects of chemical oxygen demand (COD), ammonia nitrogen, total nitrogen removal rates and nitrite accumulation are investigated under alternating oxic-anoxic model in biological nitrogen removal system——sequencing batch reactor (SBR). The system operational effect was studied by analyzing pollutants removal and nitrite accumulation changes. The results showed that the ammonium nitrogen removal rate increased gradually and reached 60% at last. The average removal rate of ammonia nitrogen was 50.2%. The average total nitrogen removal rate was 31.0% due to the low ammonia nitrogen removal and the low carbon in the inflow. The average COD removal rate was 41.7%, finally the COD removal rate reached near 60%. The average nitrite accumulation rate was 68.71%. The alternating oxic-anoxic model reached stable nitrite accumulation.


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.


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