Response of Phthalate Esters-Acclimated Activated Sludge to 2,4-Dinitrophenol

1987 ◽  
Vol 19 (3-4) ◽  
pp. 461-470 ◽  
Author(s):  
R. Yucel Tokuz

The process performance of an activated sludge system during acclimation to phthalate esters was examined. Concentration of the phthalate esters was increased gradually, and over about a two-week period, the acclimation to a mixture of 410 mg/L diethyl phthalate and 540 mg/L dimethyl phthalate was complete. It was observed that the effluent Chemical Oxygen Demand (COD) was not affected adversely in spite of increasing influent COD. Other indicators of process performance, for example, effluent suspended solids, were at acceptable levels at the completion of acclimation. The system responded well when 2,4-dinitrophenol, up to 4 mg/L, was included in the influent in addition to phthalate esters. Actually an improvement in system effluent COD was observed possibly due to increasing Mixed Liquor Suspended Solids (MLSS). At a 2,4-dinitrophenol concentration of 8 mg/L, system performance deteriorated considerably but the recovery was fast, and within a two-week period system performance returned to normal.

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
S. S. Fatima ◽  
S. Jamal Khan

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.


2020 ◽  
Vol 12 (19) ◽  
pp. 8182
Author(s):  
Nuhu Dalhat Mu’azu ◽  
Omar Alagha ◽  
Ismail Anil

Mathematical modeling has become an indispensable tool for sustainable wastewater management, especially for the simulation of complex biochemical processes involved in the activated sludge process (ASP), which requires a substantial amount of data related to wastewater and sludge characteristics as well as process kinetics and stoichiometry. In this study, a systematic approach for calibration of the activated sludge model one (ASM1) model for a real municipal wastewater ASP was undertaken in GPS-X. The developed model was successfully validated while meeting the assumption of the model’s constant stoichiometry and kinetic coefficients for any plant influent compositions. The influences of vital ASP parameters on the treatment plant performance and capacity analysis for meeting local discharge limits were also investigated. Lower influent chemical oxygen demand in mgO2/L (COD) could inhibit effective nitrification and denitrification, while beyond 250 mgO2/L, there is a tendency for effluent quality to breach the regulatory limit. The plant performance can be satisfactory for handling even higher influent volumes up to 60,000 m3/d and organic loading when Total Suspended Solids/Volatile Suspended Solids (VSS/TSS) and particulate COD (XCOD)/VSS are maintained above 0.7 and 1, respectively. The wasted activated sludge (WAS) has more impact on the effluent quality compared to recycle activated sludge (RAS) with significant performance improvement when the WAS was increased from 3000 to 9000 m3/d. Hydraulic retention time (HRT) > 6 h and solids retention time (SRT) < 7 days resulted in better plant performance with the SRT having greater impact compared with HRT. The plant performance could be sustained for a quite appreciable range of COD/5-day Biochemical Oxygen Demand (BOD5 in mgO2/L) ratio, Mixed Liquor Suspended Solid (MLSS) of up to 6000 mg/L, and when BOD5/total nitrogen (TN) and COD/TN are comparatively at higher values. This work demonstrated a systematic approach for estimation of the wastewater treatment plant (WWTP) ASP parameters and the high modeling capabilities of ASM1 in GPS-X when respirometry tests data are lacking.


1996 ◽  
Vol 34 (5-6) ◽  
pp. 43-50 ◽  
Author(s):  
P. S. Barker ◽  
P. L. Dold

Results of model simulations indicate that without the assumption of COD loss, predictions of oxygen consumption and volatile suspended solids production are significantly over-estimated for biological excess phosphorus removal (BEPR) activated sludge systems (and to a lesser extent anoxic-aerobic systems). These systems apparently consume less oxygen and produce less volatile solids than aerobic systems for the same amount of COD removal. A general model for biological nutrient removal systems has recently been presented by Barker and Dold. Three mechanisms for COD loss are suggested, based on results of COD balances for different types of activated sludge system. Model simulation results with and without the assumption of COD loss are discussed, as well as the influence of influent COD composition on predictions of volatile suspended solids concentration/production and oxygen consumption.


BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3962-3969
Author(s):  
Binfang Shi ◽  
Jingang Huang ◽  
Zhenjiang Yin ◽  
Wei Han ◽  
Shanshan Qiu ◽  
...  

Fermentative valeric acid production is a promising way to recycle valuable resources from waste activated sludge (WAS). This study investigated the feasibility of using riboflavin (RF) to enhance volatile fatty acids (VFAs) production, especially valeric acid production from WAS coupled with solid reduction. The results indicated that RF (0.5 mM) promoted the VFAs production by up to 41.0%. Valeric acid accounted for the most abundance within the VFAs components. When RF dosages were 0.05 to 5.0 mM in the WAS fermentation systems, the chemical oxygen demand fractions of valeric acid to the total VFAs were 41.0% to 62.8%, which were much higher than those using other chemical supplements. Moreover, RF enhanced the reduction of mixed liquor volatile suspended solids (MLVSS). When RF dosage was 0.2 mM, MLVSS reduction achieved a maximum at 47.4%, compared to that in the RF-free control (33.9% reduction). Riboflavin in this study was considered as a feasible chemical to enhance the fermentative valeric acid generation coupled to MLVSS reduction, realizing the reduction of solids and the reutilization of valuable resources from WAS.


Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 291 ◽  
Author(s):  
Dariusz Andraka

Analysis of wastewater treatment plant reliability is a difficult process, therefore it is often limited to selected aspects, e.g., mechanical reliability of equipment or technological availability of the process. The research presents a method of combining the above mentioned aspects in order to determine the complex operational availability index (CAVO). A hypothetical technological system with activated sludge (AS) in a typical layout (denitrification-nitrification) was selected for the studies. A number of operational scenarios have been developed, taking into account the possible mechanical failures of system components. Computer simulations with the use of Activated Sludge Model No.1 (ASM1), performed for selected scenarios allowed the determination of a complex operational availability of the system. Obtained results confirm high reliability of AS system in terms of biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS) removal (CAVO > 0.96) and indicate the necessity of further research in order to determine representative value of reliability of total nitrogen removal (from the study, CAVO-Ntot < 0.4) and to evaluate other technological solutions in terms of their complex reliability.


2003 ◽  
Vol 48 (3) ◽  
pp. 143-150 ◽  
Author(s):  
C. Yangin Gomec ◽  
R.E. Speece

The effect of pH on anaerobic solubilization of domestic primary sludge and activated sludge was investigated and compared. Anaerobic solubilization was carried out in continuously stirred anaerobic reactors at mesophilic temperature (35°C) and pH was fixed at 6.5 (pH-controlled). Many researches reported the serious effects of pH on the solubilization of organic materials. Thus, the aim of pH control in the reactors consisting of domestic primary and activated sludges, was the evaluation of retardation in hydrolysis/acidogenesis at low pH values. Since primary and activated sludges have different biodegradation characteristics, results were compared. Results indicated that the destruction of Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) were better in the pH-controlled reactors. In both sludges, acetic acid was the main Volatile Fatty Acid (VFA) produced. In the pH-controlled reactors, VSS reduction was found to be 72% in about 20 days in the anaerobic digestion of activated sludge, whereas for the same interval VSS reduction could only be achieved by 32% in primary sludge at 35°C. When primary sludge was used as substrate, the pH-uncontrolled and the pH-controlled reactors removed VSS with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). However, production of VFAs and SCOD was ceased after 5 days in the pH-controlled reactor whereas VFAs and SCOD production continued after 5 days in the pH-uncontrolled reactor, which indicated that hydrolysis and fermentation did not complete and continued longer. On the other hand; in either the pH-uncontrolled or the pH-controlled reactor of activated sludge, VSS was not removed with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). It was apparent that solubilization was occurring, however this solubilization was not observed as VFA production. When total methane production and total COD (CODtot) removal were estimated using VSS removal in both types of sludges, results indicated that pH control enhanced biogas productions as well as CODtot removals.


Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1553
Author(s):  
Pui Mun Chin ◽  
Aine Nazira Naim ◽  
Fatihah Suja ◽  
Muhammad Fadly Ahmad Usul

Rapid population growth has contributed to increased solid waste generated in Malaysia. Most landfills that have reached the design capacity are now facing closure. Taman Beringin Landfill was officially closed, so the Taman Beringin Solid Waste Transfer Station was built to manage the relocation, consolidation, and transportation of solid waste to Bukit Tagar Sanitary Landfill. Leachates are generated as a consequence of rainwater percolation through waste and biochemical processes in waste cells. Leachate treatment is needed, as leachates cause environmental pollution and harm human health. This study investigates the impact of treated leachate discharge from a Leachate Treatment Plant (LTP) on the Jinjang River water quality. The performance of the LTP in Taman Beringin Solid Waste Transfer Station was also assessed. Leachate samples were taken at the LTP’s anoxic tank, aeration tank, secondary clarifier tank, and final discharge point, whereas river water samples were taken upstream and downstream of Jinjang River. The untreated leachate returned the following readings: biochemical oxygen demand (BOD) (697.50 ± 127.94 mg/L), chemical oxygen demand (COD) (2419.75 ± 1155.22 mg/L), total suspended solid (TSS) (2710.00 ± 334.79 mg/L), and ammonia (317.08 ± 35.45 mg/L). The LTP’s overall performance was satisfactory, as the final treated leachates were able to meet the standard requirements of the Environmental Quality (Control of Pollution from Solid Waste Transfer Station and Landfill) Regulation 2009. However, the LTP’s activated sludge system performance was not satisfactory, and the parameters did not meet the standard limits. The result shows a low functioning biological treatment method that could not efficiently treat the leachate. However, a subsequent step of combining the biological and chemical process (coagulation, flocculation, activated sludge system, and activated carbon adsorption) helped the treated leachate to meet the standard B requirement stipulated by the Department of Environment (DOE), i.e., to flow safely into the river. This study categorized Jinjang River as polluted, with the discharge of the LTP’s treated leachates, possibly contributing to the river pollution. However, other factors, such as the upstream sewage treatment plant and the ex-landfill downstream, may have also affected the river water quality. The LTP’s activated sludge system performance at the transfer station still requires improvement to reduce the cost of the chemical treatment.


2004 ◽  
Vol 48 (11-12) ◽  
pp. 15-22
Author(s):  
D. Orhon ◽  
Ö Karahan-Gül ◽  
S.l Sözen ◽  
N. Artan

The study presents an evaluation of the oxygen requirement and sludge production, modeled in terms of fundamental processes reflecting different biochemical transformations in activated sludge systems. Modern modeling concepts define substrate utilization and endogenous decay as major processes requiring final electron acceptors. Substrate and sludge components may be defined in terms of different parameters. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) are the traditional substrate parameters. COD also serves to define biomass along with volatile suspended solids (VSS) parameter. Estimation of oxygen requirement and sludge production for aerobic activated sludge systems covering basic biochemical processes are defined for different substrate and sludge parameters, considering that each calculation is associated with a different stoichiometry on the basis of a selected parameter set. The German regulations are examined and the biochemical bases of the coefficients in the regulatory expressions are set in terms of fundamental model constants.


2013 ◽  
Vol 67 (11) ◽  
pp. 2437-2443 ◽  
Author(s):  
Jianzheng Li ◽  
Yu Jin ◽  
Yaqiong Guo ◽  
Junguo He

An anaerobic phosphorus release tank was introduced to an anaerobic–anoxic–aerobic (A2/O) process treating domestic sewage to enhance the phosphorus removal at low temperature. Phosphorus release of the activated sludge from the second sedimentation tank was evaluated at 14 °C by batch cultures, and the nutrient removal in the modified low temperature A2/O process was further investigated at the same temperature. The results showed that the feasible sludge retention time was 14 h for sequencing batch reaction and 12 h for continuous flow operation. The ratio of raw sewage to activated sludge from the second sedimentation tank was 1:1 in volume to meet the demand of carbon resource for the growth of phosphorus release microbes. The feasible chemical oxygen demand (COD) loading rate of the activated sludge in the phosphorus release tank was 0.015–0.02 g COD/g MLSS (mixed liquor suspended solids) and the nitrate concentration should be less than 5 mg/L. The phosphorus release was doubled when the sludge was blended intermittently and gently. The anaerobic phosphorus release of the activated sludge improved the phosphate removal remarkably, as well as the removal of NH4+-N and total nitrogen (TN) in the modified low temperature A2/O process. The effluent COD, NH4+-N, TN and total phosphorus could meet a stricter discharge standard.


2015 ◽  
Vol 72 (6) ◽  
pp. 966-973 ◽  
Author(s):  
J. Wu ◽  
Y. Jiang ◽  
Z. P. Cao ◽  
Z. H. Li ◽  
Y. Y. Hu ◽  
...  

A novel digester, termed an internal circulation anaerobic digester (ICAD), was developed to intensify sludge digestion. It consists of reaction zone, settling zone, thickening zone, riser and downcomer. Internal circulation in the digester is intensified by backflow biogas. The mesophilic ICAD treating thermal pretreated waste activated sludge with volatile suspended solids (VSS)/suspended solids (SS) of 0.45–0.49 was conducted in this study to reduce and stabilize the low organic content sludge. The results showed that the VSS removal rate and biogas rate reached 46.0% and 0.72 m3/kg VSSfed at hydraulic retention time (HRT) of 15 days. VSS/SS and soluble chemical oxygen demand (SCOD) of the effluent sludge ranged from 0.39 to 0.41 and 274 mg/L to 473 mg/L, respectively, under various HRTs from 10 to 27 days. The degradation ability of ICAD derived from the improved mass transfer by internal circulation and long solid retention time at short HRT is compared with continuous stirred tank reactor.


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