The impact of sea water flushing on biological nitrification-denitrification activated sludge sewage treatment process

2002 ◽  
Vol 46 (11-12) ◽  
pp. 209-216 ◽  
Author(s):  
S.M. Yu ◽  
W.Y. Leung ◽  
K.M. Ho ◽  
P.F. Greenfield ◽  
W.W. Eckenfelder
Keyword(s):  
Activated Sludge ◽  
Capital Investment ◽  
Sea Water ◽  
Initial Period ◽  
Sewage Treatment ◽  
Ammonia Nitrogen ◽  
Inhibitory Effects ◽  
Original Design ◽  
Activated Sludge Processes ◽  
The Impact

The process performance of the two largest activated sludge processes in Hong Kong, the Sha Tin and the Tai Po Sewage Treatment Works (STW), deteriorated in the initial period after the introduction of seawater flushing in 1995 and 1996, respectively. High effluent ammonia nitrogen (NH4-N) and total suspended solids (TSS) in excess of the discharge standards resulted from incomplete nitrification and changes in floc characteristics. A desktop study on the inhibitory effects of salinity, particularly on nitrification, was subsequently conducted using the Tai Po STW operating data. To assist the upgrade of the Sha Tin STW a five-month extensive bench-scale investigation on a simple but flexible modified Ludzack-Ettinger configuration with bio-selector was conducted to quantify the inhibitory effects due to the saline concentration. The Sha Tin STW upgrade consists of restoration of its original design capacity (conventional process) of 205,000 m3/day from its currently much reduced capacity as a Bardenpho process. Only the volume of the existing biological process and clarifier is to be utilized. The saline concentration ranges from 3,500 up to 6,500 mg Cl-/L, both daily and seasonally. High and greatly fluctuating saline concentrations have been known to inhibit nitrification. Design consideration should also be given to the peak daily and seasonal TKN loading of up to three times the average. Although the nitrifiers maximum specific growth rate was significantly reduced to a low 0.25 day−1, the inhibition was considered to be tolerable with effluent NH4-N and NO3-N consistently at < 1 and < 6 mg/L. The bio-selector was demonstrated to be efficient in control of sludge foaming and bulking with SVI consistently ≤ 125 mL/g. Results from the IAWQ Model No. 1 and the hydraulic model of the secondary clarifiers allowed overall process capacity maximization. With an anoxic mass fraction of 25-30%, operating sludge age of 9-14 days and SVI ≤ 125 mL/g, both the design requirements and the effluent discharge standards could be met. Without these investigations, an unnecessarily large reaction basin and secondary clarifier volume, and hence capital investment, would have resulted.

scholarly journals Graphene-Modulated Removal Performance of Nitrogen and Phosphorus Pollutants in a Sequencing Batch Chlorella Reactor

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2181 ◽  
Author(s):  
Gonghan Xia ◽  
Wenlai Xu ◽  
Qinglin Fang ◽  
Zishen Mou ◽  
Zhicheng Pan
Keyword(s):  
Optical Microscopy ◽  
Sewage Treatment ◽  
Ammonia Nitrogen ◽  
Pollutant Removal ◽  
Plate Count ◽  
Nitrogen And Phosphorus ◽  
Removal Rates ◽  
Practical Support ◽  
Plate Count Method ◽  
The Impact

In this work, the influence of graphene on nitrogen and phosphorus in a batch Chlorella reactor was studied. The impact of graphene on the removal performance of Chlorella was investigated in a home-built sewage treatment system with seven identical sequencing batch Chlorella reactors with graphene contents of 0 mg/L (T1), 0.05 mg/L (T2), 0.1 mg/L (T3), 0.2 mg/L (T4), 0.4 mg/L (T5), 0.8 mg/L (T6) and 10 mg/L (T7). The influence of graphene concentration and reaction time on the pollutant removal performance was studied. The malondialdehyde (MDA) and total superoxide dismutase (SOD) concentrations in each reactor were measured, and optical microscopy and scanning electron microscopy (SEM) characterizations were performed to determine the related mechanism. The results show that after 168 h, the total nitrogen (TN), ammonia nitrogen (AN) and total phosphorus (TP) removal rates of reactors T1–T7 become stable, and the TN, AN and TP removal rates were gradually reduced with increasing graphene concentration. At 96 h, the concentrations of both MDA and SOD in T1–T7 gradually increased as the graphene concentration increased. In optical microscopy and SEM measurements, it was found that graphene was adsorbed on the surface of Chlorella, and entered Chlorella cells, deforming and reducing Chlorella. Through the blood plate count method, we estimated an average Chlorella reduction of 16%. According to the water quality and microscopic experiments, it can be concluded that the addition of graphene causes oxidative damage to microalgae and destruction of the Chlorella cell wall and cell membrane, inhibiting the nitrogen and phosphorus removal in Chlorella reactors. This study provides theoretical and practical support for the safe use of graphene.

Use of microtox tests for screening industrial wastewater toxicity

1996 ◽  
Vol 34 (10) ◽  
pp. 43-50 ◽  
Author(s):  
Oliver J. Hao ◽  
Shin Chien-Jen ◽  
Lin Cheng-Fang ◽  
Jeng Fu-Tien ◽  
Chen Zen-Chyuan
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Industrial Wastes ◽  
Wastewater Management ◽  
Waste Discharge ◽  
Significant Toxicity ◽  
Microtox Toxicity ◽  
Microtox Test ◽  
Activated Sludge Processes ◽  
The Impact

Conventional parameters such as chemical oxygen demand and suspended solids may not detect toxic compounds present in a variety of industrial wastewaters and treated wastes. Thus, the presence of toxicity in many industrial wastes presents a significant impact on biological wastewater treatment, and exerts adverse effects on receiving waters. Because of their easy technique and rapid turnaround results, the Microtox tests were used in this study to pinpoint unusual wastewaters, evaluate the toxicity reduction through activated sludge processes, observe the impact of excessive chemical addition to meet the transparency standard, and measure the impact of waste discharge on one particular receiving water. It was found that the results of Microtox tests were useful for such purposes; i.e., low COD wastes exhibited high Microtox toxicity; some activated sludge processes removed significant toxicity; and some effluents from coagulation/oxidation processes showed an increased toxicity. The application of the Microtox test to wastewater management is discussed.

scholarly journals Removal of Ammonia Nitrogen by Activated Sludge Process Using Simultaneous Nitrification Denitrification Method

2020 ◽  
Vol 202 ◽  
pp. 05006
Author(s):  
Junaidi ◽  
Sri Sumiyati ◽  
Ronauli Sitinjak
Keyword(s):  
Activated Sludge ◽  
Operating Time ◽  
Carbon Sources ◽  
Ammonia Nitrogen ◽  
Nitrogen Inputs ◽  
Nitrogen Concentrations ◽  
Nitrification And Denitrification ◽  
Nitrite Nitrate ◽  
Biological Nitrogen ◽  
Activated Sludge Processes

Nitrogen concentrations are often found in ammonia, nitrite, nitrate, and neutral nitrogen waters. This research has investigated the simultaneous removal of biological nitrogen nitrification and denitrification (SND) in a continuous flow system of activated sludge processes. This research was conducted by variations in carbon sources is namely glucose and methanol. Variations of C / N ratios of 5, 10, and 20 were also carried out. The main parameters were analyzed every day until the end of the research period. The main parameter analyzed is ammonia-nitrogen. Besides, additional parameters were also analyzed in the form of COD, nitrate-nitrogen, nitrite-nitrogen, pH, MLSS, SVI, and DO. The results of research indicate artificially excess nitrogen wastewater can be treated using SND and can produce sufficiently good effluent quality if the operations are running optimally. The highest ammonia-nitrogen removal efficiency of 100% shown by the variation of the carbon methanol source and value of the C / N 20 ratio then followed by the C / N 10 ratio of 78% and the C / N 5 ratio of 59%. Overall, the data shown appropriate controls for carbon and nitrogen inputs are needed to achieve an efficient SND. Proper SND technology can save operating time and energy, and may replace two traditional stages: biological nitrification and denitrification processes.

Batch Operated Activated Sludge Plant for Production of High Effluent Quality at Small Works

1993 ◽  
Vol 28 (10) ◽  
pp. 251-258 ◽  
Author(s):  
B. Chambers
Keyword(s):  
Activated Sludge ◽  
Sewage Treatment ◽  
Batch Process ◽  
Ammonia Nitrogen ◽  
Aeration Tank ◽  
Coated Steel ◽  
Effluent Quality ◽  
Water Companies ◽  
The Uk ◽  
Activated Sludge Systems

In the UK there are about 7500 sewage treatment works of which 85% serve populations of less than 5000. Many of the smaller works do not comply with effluent quality standards and options for improving treatment are being pursued by many water companies. WRc have developed designs for packaged activated sludge systems to serve populations in the range 100 - 1000 persons. A detailed design has been completed for a population equivalent of about 600. Target effluent quality is 15:20:5 mg/l of BOD, SS and ammonia nitrogen respectively on a 95 percentile basis. The activated sludge system is designed to operate as a batch process with aeration and sludge settlement both occurring in the same tank. Batch operated activated sludge plants are known to produce sludges with good settling properties providing the influent wastewater is admitted into the aeration tank in controlled manner. Therefore a specially designed holding tank has been included as the first stage in the treatment sequence. All process tanks are specified as glass-coated steel installed on a flat concrete base. Target construction cost for 600 population is ₤350 per capita.

Boston Harbor Clean-Up: Comparison of Conventional Oxygen Activated Sludge with and without Anaerobic Selectors

1992 ◽  
Vol 25 (4-5) ◽  
pp. 281-287 ◽  
Author(s):  
P. T. Bowen ◽  
V. S. Magar ◽  
R. Otoski ◽  
T. McMonagle
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Pilot Scale ◽  
Ammonia Nitrogen ◽  
Design Parameters ◽  
Boston Harbor ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Activated Sludge Processes ◽  
Treatment Design

To determine secondary treatment design parameters for the Massachusetts Water Resources Authority Deer Island Treatment Facility, a pilot study was conducted. Due to the constricted site, oxygen activated sludge processes were considered. A pilot-scale conventional oxygen activated sludge (COAS) and COAS preceded by an anaerobic selector process (ASP) were compared. Both processes achieved comparable levels of total and soluble BOD, total and soluble COD, total nitrogen, ammonia nitrogen, and phosphorus removal. Higher percent removals occurred during the spring and summer flow periods. Neither process appeared more stable than the other with respect to changing influent loading and hydraulic stress. Differences in the process were the sludge settleability and sludge yield. The ASP had a slightly higher sludge yield than COAS, but the solids settled faster.

Research on the Impact of Precipitates Produced with Fe2+ as a Coagulant Plays on Water Quality

2014 ◽  
Vol 687-691 ◽  
pp. 4339-4342
Author(s):  
Ying Zhang ◽  
Lei Zhu ◽  
Jie Fan
Keyword(s):  
Water Quality ◽  
Activated Sludge ◽  
Significant Influence ◽  
Phosphorus Removal ◽  
Treatment Process ◽  
Sewage Treatment ◽  
Phosphate Content ◽  
Change Trend ◽  
The Impact

Fe2+ is widely used as a coagulant to enhance the primary SBR sewage treatment process. Based on SBR system, this paper studies the change trend of phosphate content in various stages by simulating the interaction between sewage and the precipitates produced with Fe2+ in the sediment as a coagulant. The results indicate that excluding the impact of activated sludge, the concentration of PO43+ increases in the end of the anaerobic stage with the increase of FePO4 cumulant in the sediment and there is an equimultiple relationship between the increase of the concentration of PO43+ in the effluent and the FePO4 dosage and that the accumulation of Fe (OH)3 can contribute to the subsequent sustainable phosphorus removal, but the cumulant increase of Fe (OH)3 has no significant influence on the effects of phosphorus removal.

Intra-product Specialisation and the Innovation Ability of the High-technology Industry in China

2017 ◽  
Vol 22 (1) ◽  
pp. 144-164
Author(s):  
Hongjian Cao ◽  
Hui Zhang ◽  
Jun Li ◽  
Yumin Liu
Keyword(s):  
Technical Efficiency ◽  
Capital Investment ◽  
Initial Period ◽  
High Technology ◽  
Dynamic Panel Data ◽  
Scale Efficiency ◽  
Technology Industry ◽  
High Technology Industry ◽  
Innovation Ability ◽  
The Impact

The purpose of this paper is to analyse the influence of intra-product specialisation on the innovation ability of the high-technology industry in China. To achieve this research goal, we use the generalised method of moments (GMM) with a dynamic panel data model in our empirical research. Total factor productivity (TFP) and its decomposition variables are used to measure the innovation ability. The Malmquist index is employed to calculate TFP and its decomposition variables, namely, technology progress, technical efficiency and scale efficiency. Previous studies show that intra-product specialisation can raise TFP, but our empirical results reveal that the impact of the intra-product specialisation on the TFP is uncertain: it decreases TFP in the initial period but increases it in the lag period. Results also indicate that an increase in the proportion of state-owned property rights exerts a positive influence on TFP and the change in pure technical efficiency. Technical efficiency is greatly influenced by intra-product specialisation, whereas intra-product specialisation exerts a slight influence on technological progress. The capital investment in research and development (R&D) has a positive effect on TFP, and the contribution rate of R&D labour input to TFP is relatively low. The main conclusion is that China need to improve the degree of intra-product specialisation, accelerate the evolution of industry technical standards and reduce the coordination cost of intra-product specialisation to enhance the innovation ability of the high-technology industry.

Impact of SRT on Simultaneous Nitrification and Denitrification in a Carrousel Oxidation Ditch for Sewage Treatment

2012 ◽  
Vol 550-553 ◽  
pp. 2104-2107
Author(s):  
Yi Ming Chen
Keyword(s):  
Sewage Treatment ◽  
Pilot Scale ◽  
Ammonia Nitrogen ◽  
Municipal Sewage ◽  
Simultaneous Nitrification And Denitrification ◽  
Oxidation Ditch ◽  
Treatment Efficiency ◽  
Nitrification And Denitrification ◽  
Carrousel Oxidation Ditch ◽  
The Impact

The impact of SRT on simultaneous nitrification and denitrification (SND) in the Carrousel Oxidation Ditch was carried out based on pilot-scale to treat low COD/TN municipal sewage. The impact factor, sludge retention time (SRT), was investigated on the occurrence of SND. The experiment results showed that in the oxygen-deficient environment whose DO was 0.3 mg/L, R of 50%, MLSS of 4000 mg/L, the treatment efficiency achieved the best with SRT of 20 d, the COD, ammonia nitrogen, total nitrogen (TN) of effluent were lower than 32 mg/L, 5 mg/L, 13 mg/L, respectively, which was observed efficient phenomenon of SND. Overall, these results demonstrated that the Carrousel Oxidation Ditch with the occurrence of SND could have the potential to treat low C/N sewage.

Performance of Sequencing Batch Reactor Activated Sludge Processes for Simultaneous Removal of Nitrogen, Phosphorus and Bod as Applied to Small Community Sewage Treatment

1986 ◽  
Vol 18 (7-8) ◽  
pp. 363-370 ◽  
Author(s):  
M. Okada ◽  
R. Sudo
Keyword(s):  
Activated Sludge ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Sewage Treatment ◽  
Phosphorus Release ◽  
Synthetic Wastewater ◽  
Simultaneous Removal ◽  
Small Community ◽  
Activated Sludge Processes ◽  
Nitrogen Phosphorus

Laboratory-scale sequencing batch reactor (SBR) activated sludge process was fed with synthetic wastewater to clarify the possibility of simultaneous removal of nitrogen, phosphorus, and organic substances by modifying operational schedule. Anoxic and/or anaerobic reactions in addition to aerobic reactions were introduced into a cycle of batch operation. Simultaneous removal of nitrogen, phosphorus and organic carbon was shown to be possible by the modified operation of SBR into which reactions without aeration (anoxic/anaerobic) were introduced during the fill period. Oxidized nitrogen remaining in the reactor at the end of the former cycle was removed by denitrification during the fill. Anaerobic conditions after the denitrification was completed enhanced phosphorus release from the sludge and the following luxury uptake during aeration removed phosphorus from water. Both extension and reduction of anoxic/anaerobic period in the beginning of a cycle damaged phosphorus removal and sludge settlability. Thus, an optimum length of period for these reactions must be chosen for successful operations. The best length of this period coincided with that of the fill within the range of this study.

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