Kinetics Of Organic Matter Removal Research Articles

Exploring the Removal of Organic Matter in Constructed Wetlands Using First Order Kinetic Models

Mathematical models have become an excellent tool to evaluate the characteristics and performance of Constructed Wetlands (CWs). They help to characterize the dynamics of pollutant removal in these systems. The aim of this research was to evaluate the kinetics of organic matter removal in CWs using two models: (i) the conventional first order model and (ii) the sigmoidal or k-n model. For this purpose, data from 41 CWs where domestic sewage is treated were used. The cluster analysis was performed to identify similar groups of CWs based on the estimation of model coefficients. According to the results obtained, the model that provides a better fit for the removal of organic matter in CWs is the sigmoidal-type. However, its “n” coefficient, which would represent an increase in resistance to degradation, remains a not totally explained variable. The sigmoidal or k-n model is promising, presenting good adjustment indices.

Polishing low-biodegradable and saline industrial effluent in a full-scale horizontal subsurface flow constructed wetland: evaluation of bio-treatability and predictive power of kinetic models

This study evaluates the bio-treatability performance and kinetic models of full-scale horizontal subsurface flow constructed wetland used for the tertiary treatment of composite industrial effluent characterized by high-salt content ranging from 5830 to 10,400 µS/cm and biochemical oxygen demand (BOD5): chemical oxygen demand (COD) ratio below 0.2. The wetland vegetated with Phragmites australis was operated in a semi-arid climate under an average hydraulic loading rate of 63 mm/d. The results of a 4-year operation calculated based on the concentration of pollutants showed that the average removal efficiency of COD, BOD5, and total suspended solids (TSS) were 17.5, 5.1, and 11.2%, respectively. The system reduced up to 6.5 ± 0.7% of electrical conductivity presenting poor phyto-desalination potential without considering the contribution of evapotranspiration in water balance in contrast to satisfying performance for heavy metals reduction. The comparison of the kinetics of organic matter removal obtained by the first-order and Monod models paired with continuous stirred-tank reactor and plug flow regime showed that Monod-plug flow model provided the best fit with the constants of 2.01 g COD/m2·d and 0.3014 g BOD5/m2·d with the best correlation coefficient of 0.610 and 0.968 between the predicted and measured concentrations, respectively. The low kinetic rates indicate that the process is capable of effluent polishing instead of purification due to the presence of organic compounds recalcitrant to biodegradation and a high level of salinity.

Performance of a pilot-scale aquaponics system using hydroponics and immobilized biofilm treatment for water quality control

Aquaponics is considered as a promising approach to mass produce both fish meat and vegetable at high rates without discharge pollutants. A novel aquaponics system is proposed to control water quality and enhance nutrition efficiency with high rate immobilized biofilm units, including mass-bio system (MBS) and fiber biofilter (FB), installed between upstream hydroponics units, which are composed of the media filled beds (MFD) and nutrient film technique (NFT), and downstream aquaculture unit for fish rearing. A pilot test was conducted over 130 d to characterize the performance of proposed system which converted residual nutrients from aquaculture unit into ammonium and nitrate at balanced ratio for aquatic plant growth and then removed residual ammonium or/and nitrite to ensue recycled water quality for fish rearing. The kinetics of organic matter removal and nutrient conversion in hydroponics unit and immobilized biofilm units were determined via batch assays over 24 h in the system. The estimated daily pollutant increments for TAN, NO2−-N, NO3−-N, TN, DTP and TOC in the system were 0.28, 0.17, 0.20, 0.64, 0.56 and 2.19 mg/L, respectively. The results demonstrated that total ammonia nitrogen (TAN), nitrite (NO2−-N), nitrate (NO3−-N), total nitrogen (TN), dissolved total phosphorus (DTP) and total organic carbon (TOC) were maintained at low levels in the system for a long-term. Aquatic plants in MFD and NFT contributed to the removal of TAN, NO2−-N, NO3−-N, TN and DTP. The removal efficiencies of MFD versus NFT for TAN were 71.4% vs 43.5% for TAN and 62.5% vs 52.3% for DTP. MBS and FB performed the removal of TAN, NO2−-N and TOC. The 24 h removal efficiencies of TAN, NO2−-N and TOC were 71.8%, 58.5% and 3.7% for MBS and 15.7%, 7.7% and 27.2% for FB.

Kinetics of organic matter removal and humification progress during sewage sludge composting

This study investigated the kinetics of organic matter (OM) removal and humification during composting of sewage sludge and lignocellulosic waste (wood chips, wheat straw, leaves) in an aerated bioreactor. Both OM degradation and humification (humic substances, HS, and humic acids, HA formation) proceeded according to 1. order kinetics. The rate constant of OM degradation was 0.196d−1, and the rate of OM degradation was 39.4mg/gOMd. The kinetic constants of HS and HA formation were 0.044d−1 and 0.045d−1, whereas the rates of HS and HA formation were 3.46mgC/gOMd and 3.24mgC/gOMd, respectively. The concentration profiles of HS and HA indicated that humification occurred most intensively during the first 3months of composting. The high content of HS (182mgC/gOM) in the final product indicated that the compost could be used in soil remediation as a source of HS for treating soils highly contaminated with heavy metals.

Effects of oligomerization phenomenon on dissolved organic matter removal kinetics on novel activated carbons

The overall objective of this research was to determine the effects of oxidative coupling (oligomerization) phenomenon on the adsorption kinetics of dissolved natural organic matter (DOM) on novel tailored activated carbons. A comparison of adsorption kinetics data collected in the presence and absence of phenolic compounds under both oxic (presence of molecular oxygen) and anoxic (absence of molecular oxygen) conditions showed that the adsorption rate of DOM was strongly affected by the oligomerization phenomenon. The diffusion rate of DOM is in inverse proportion to the critical oxidation potential of the phenolic compound. In addition, the roles of carbon physicochemical characteristics and DOM molecular weight distribution were also investigated. Tailored activated carbon impregnated with manganese oxide was found to play an important role in promoting complexation reactions between DOM and phenolic compounds. Meanwhile, Fulvic acid molecules (component of DOM) with molecular weight below 2000Da appeared to have more potential to get influenced from oligomerization effects.

Performance of an anaerobic-aerobic reactor and kinetic study of organic matter removal of cattle slaughterhouse effluent

This paper sought to evaluate the behavior of an upflow Anaerobic-Aerobic Fixed Bed Reactor (AAFBR) in the treatment of cattle slaughterhouse effluent and determine apparent kinetic constants of the organic matter removal. The AAFBR was operated with no recirculation (Phase I) and with 50% of effluent recirculation (Phase II), with θ of 11h and 8h. In terms of pH, bicarbonate alkalinity and volatile acids, the results indicated the reactor ability to maintain favorable conditions for the biological processes involved in the organic matter removal in both operational phases. The average removal efficiencies of organic matter along the reactor height, expressed in terms of raw COD, were 49% and 68% in Phase I and 54% and 86% in Phase II for θ of 11h and 8h, respectively. The results of the filtered COD indicated removal efficiency of 52% and k = 0.0857h-1 to θ of 11h and 42% and k = 0.0880h-1 to θ of 8h in the Phase I. In Phase II, the removal efficiencies were 59% and 51% to θ of 11h and 8h, with k = 0.1238h-1 and k = 0.1075 h-1, respectively. The first order kinetic model showed good adjustment and described adequately the kinetics of organic matter removal for θ of 11h, with r² equal to 0.9734 and 0.9591 to the Phases I and II, respectively.

Kinetic Analysis on Rotating Biological Contactor Treatment of Organic Matter

This paper adopts a 3-stage rotating biological contactor (RBC), studies kinetic analysis on RBC treatment of organic matter .Water temperature 25 °C and hydraulic retention time (HRT) 5h , COD concentration of influent varies from about 400 to 700mg / L, the average COD removal rate is 85% . According to Monod and Michaelis-Menten formula, organic matter removal kinetics equation in the first stage of RBC can be catched. When DO≥2mg/L, organic matter removal kinetic equation: U1=7.02S1/( S1+640.70), DO<2mg/L, organic matter removal kinetic equation: U2=35.97S2/( S2+4848.92) .Where U is substrate removal rate of unit area of disc, S is the organic matter concentration of substrate. Some reference values of the equation are very useful for practical application of RBC.

Remoção de matéria orgânica e determinação de parâmetros cinéticos em sistemas alagados construídos em escala laboratorial

The objective of this study was to evaluate the performance of constructed wetland systems (SACs) for treatment of swine wastewater (ARS) under different organic loads (TCOA), and obtain kinetic parameters for sizing of the SACs. The SACs consisted of two tanks measuring 0.40 x 0.10 x 0.15 m, constructed of glass and filled with a 0.13 m layer of pea gravel; these were installed within a BOD incubator to maintain a 20°C temperature. The SACs were not cultivated and were submitted to average TCOA concentrations of 246 (SAC1) and 328 kg ha -1 day -1 of BOD (SAC2) for 51 days. With regard to the removal of organic matter, in the form of TSS, BOD and COD, no statistical difference was verified (p > 0.05) between the SACs, being that the average removal efficiencies for the referred variables in SAC1 and SAC2 were 68 and 76%, 66 and 73%, and 55 and 58%, respectively. The models proposed by Brasil et al. (2007) and Kadlec and Wallace (2008) presented good fit and adequately described the kinetics of organic matter removal (BOD and COD) from the evaluated systems, generally presenting R2 greater than 99%.

Kinetics of Organic Matter Degradation in an Upflow Anaerobic Filter Using Slaughterhouse Wastewater

An assessment of a lab-scale Upflow Anaerobic Filter (UAF) reactor used to treat slaughterhouse wastewater was carried out with varying operating conditions for Hydraulic Retention Time (HRT) and temperature. The best organic matter removal efficiency, measured as Chemical Oxygen Demand (COD), was 86.1% at HRT of 24h at 35oC. Under steady state conditions, the first-order, Stover-Kincannon and Grau-second-order kinetic models were used to represent the kinetics of organic matter removal in the UAF. The experimental data showed that the Stover-Kincannon and Grau kinetic models were the most suitable for predicting organic matter degradation. The kinetic analysis was used to establish two exponential relationships for determining the kinetic constants for both the Stover-Kincannon and Grau models as a function of temperature within the mesophilic interval studied. The results from this research study enable the determination of organic matter velocities, times and efficiencies of degradation which can be used in the design of an UAF for slaughterhouse wastewater.

Treatment of petroleum refinery sourwater by advanced oxidation processes

The performance of several oxidation processes to remove organic pollutants from sourwater was investigated. Sourwater is a specific stream of petroleum refineries, which contains slowly biodegradable compounds and toxic substances that impair the industrial biological wastewater treatment system. Preliminary experiments were conducted, using the following processes: H2O2, H2O2/UV, UV, photocatalysis, ozonation, Fenton and photo-Fenton. All processes, except Fenton and photo-Fenton, did not lead to satisfactory results, reducing at most 35% of the sourwater dissolved organic carbon (DOC). Thus, further experiments were performed with these two techniques to evaluate process conditions and organic matter removal kinetics. Batch experiments revealed that the Fenton reaction is very fast and reaches, in a few minutes, an ultimate DOC removal of 13–27%, due to the formation of iron complexes. Radiation for an additional period of 60min can increase DOC removal up to 87%. Experiments were also conducted in a continuous mode, operating one 0.4L Fenton stirred reactor and one 1.6L photo-Fenton reactor in series. DOC removals above 75% were reached, when the reaction system was operated with hydraulic retention times (HRT) higher than 85min. An empirical mathematical model was proposed to represent the DOC removal kinetics, allowing predicting process performance quite satisfactorily.

Role of Bioflocculation on Chemical Oxygen Demand Removal in Solids Contact Chamber of Trickling Filter/Solids Contact Process

The trickling filter/solids contact ~TF/SC! process was developed in the late 1970s to improve the quality of the final effluent from existing trickling filter plants, to be able to meet stricter Environmental Protection Agency effluent requirements. Although this process has successfully achieved this objective, it is still not completely understood, there is limited information regarding the floccu- lation phenomena occurring in the solids contact chamber ~SCC!, and no information could be found on the relationship between flocculation and organic matter removal kinetics. To better understand the kinetics of biological flocculation in a continuous flow SCC, a long-term experimental program was conducted using a TF/SC pilot plant constructed at the Marrero, La., wastewater treatment plant. This program started in January 1998 and has continued through date. The present article will focus on two major areas: ~1! the kinetics of bioflocculation in the SCC; and ~2! effect of bioflocculation on chemical oxygen demand ~COD! removal. Analysis of the wastewater composition revealed that, on the average, only 18.7% of the total COD in the SCC influent is truly dissolved. Therefore, most of the total COD removal observed in the SCC must be due to a physical process, such as flocculation. The experimental data confirmed that flocculation of the particulate COD contained in the trickling filter effluent explains the high total COD removal observed at the SCC. Both total and colloidal COD removals are well explained by the first-order flocculation model.

Kinetics of Organic Matter Removal in a Chemical Sequential Reactor (CSR)

The Chemical Sequential Reactor (CSR) can be considered as an advanced oxidation process able to treat wastewaters with ozone. Its operation involves a succession of acidic and alkaline pH conditions throughout continuous ozonation. The two oxidation mechanisms (direct reaction of molecular ozone and hydroxyl free radical reactions], coupled with carbon dioxide stripping, increase removal rates and ozone efficiency. Ozone efficiency is also maintained for longer periods.