Non-biodegradable Organic Matter Research Articles

Long-term variations in water quality in the lower Han River

The Han River is the main water resource for the Seoul metropolitan area (Korea) with twenty million people relying on it, and its eutrophication is of great concern for preserving drinking water quality. In this study, long-term trends in biological oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), and suspended solids at a downstream site of the river (St. Gui) are presented from 1989 to 2006 using data from the Ministry of the Environment. Longitudinal distributions in TP, TN, and chlorophyll-a concentration were measured in the downstream reaches between the Paldang Dam and Haengju Bridge. The long-term average BOD was 1.82 ± 0.67 mg/L and showed a decreasing trend, whereas COD did not vary consistently with a long-term average of 3.46 ± 0.87 mg/L, and consequently, the BOD/COD ratio decreased. This pattern can be interpreted as an increasing trend in the nonbiodegradable organic matter/biodegradable organic matter ratio, which can be attributed to enhanced sewage treatment. The long-term record for concentration did not show a consistent delate trend, whereas the seasonal variation was remarkably large with high concentrations during the flood season. In contrast, phytoplankton density was higher during low-flow seasons. It seemed that hydraulic residence time was the major factor controlling phytoplankton, as is typical in a lotic environment, which overwhelmed the effects of other factors such as temperature, nutrients, and solar radiation. In conclusion, BOD has decreased in the lower Han River system, but nonbiodegradable organic matter and phosphorus concentrations have not decreased.

Integrating toxicity testing in the wastewater management of chemical storage terminals – A proposal based on a ten-year study

Wastewater control at storage terminals of liquid chemical products in bulk is very difficult because of the variety of products handled in the facilities generating effluents of variable composition. The main objective of this work was to verify if the Vibrio fischeri acute toxicity test could be routinely included in the wastewater management of those facilities along with physical and chemical analysis in order to evaluate and improve the quality of the generated effluents. The study was performed in two phases before and after the implementation of better operational practices/treatment technologies. Chemical oxygen demand (COD) and toxicity of treated effluents did not correlate showing that effluents with low COD contain toxic substances and non-biodegradable organic matter, which may be not degraded when discharged into the aquatic environment. Segregation of influents or pre-treatment based on toxicity results and biodegradability index were implemented in the facilities generating significant improvements in the quality of final effluents with reduction of Biochemical oxygen demand (BOD) and toxicity. The integration of physical and chemical analysis with the V. fischeri toxicity test turned out to be an excellent tool for wastewater management in chemical terminals allowing rapid decision making for pollution control and prevention measures. Reuse of rain water was also proposed and when implemented by the facilities resulted in economical and environmental benefits.

An advanced oxidation process using ionized gas for wastewater treatment

This study on removing non-degradable materials in wastewater focused primarily on advanced oxidation methods such as ozone, ozone/UV and ozone/H2O2. Wastewater treatment using an ionized gas from plasma has been actively progressing. The ionized gas involves reactive species such as O2+, O2- cluster, O radical and OH radical. Since the ionized gas method has such outstanding characteristics as relatively simple structures, non-calorification, non-toxicity and low electricity consumption, it evidently of interest as a new process. A series of experiments were conducted to demonstrate the feasibility of ionized gas as a useful element for the diminution of nondegradable organic matters. On the other hand, a large amount of organic matters were changed to hydrophilic and the compounds containing aromatic functional group gradually decreased. The results implied that the ionized gas has been able to degrade the non-biodegradable organic matters. Therefore, the oxidation process by using an ionized gas process could be considered as an effective alternative unit in water and wastewater treatment plants.

Modeling of Biodegradation in an Old Unregulated European Landfill

In this note an example of modeling of biodegradation processes of an old abandoned municipal solid waste landfill for its simulation is illustrated using the landfill dynamic simulation tool MODUELO. In this program the waste biodegradation model is based on the quantification of organic matter, its chemical composition, biodegradability, accessibility to microorganisms, and the ratio nonbiodegradable leachable organic matter to gasifiable matter. Data from a characterization campaign, presented elsewhere, were used to determine these parameters. The experimental information was completed with safety factors (to compensate for sampling uncertainty) and literature values. The degradation rates were determined, after having calibrated the hydrological model, by fitting the temporal series of pollutants’ concentration measured in the leachate and the biogas composition. The achieved fit of the simulated series compared to the measured data is reported as the result of this work. Given the limited informatio...

Monitoring of organic load in a tropical urban river basin (Cameroon) by means of BOD and oxydability measurements

The tenor in organic matter has been assessed in an urban aquatic ecosystem the Mfoundi River Basin of Cameroon.The double technique of the Biochemical Oxygen Demand (BOD5) and the Oxydability test have been employed in this assessment. The results obtained indicate a high content of organic matter in the watershed with the highest values of BOD 297.5mg O2dm–3 and Oxydability 50.255mg O2dm–3 observed at the Akeu stream. The spearman correlation coefficient between BOD5 and Oxydability for the seasonal distribution is 0.22 which is positive but not statistically significant due to a high variability of biodegradable and non-biodegradable organic matter present in the river basin. The same value calculated between these organic tests with respect to the sampling sites is negative (–0.15) due probably to their abiotic and biotic heterogeneity. The results reveal a high tenor in organic matter in the hydro-system during the dry season, with a relative reduction during the rainy season, a situation that exposes the population of Yaoundé and its environs to acute pollution which can lead to numerous water related health hazards.

Physico-chemical and biological treatment of MSW landfill leachate

This paper analyses the evolution of the physico-chemical characteristics of the leachate from the Central Landfill of Asturias (Spain), which has been operating since 1986, as well as different treatment options. The organic pollutant load of the leachate, expressed as chemical oxygen demand (COD), reached maximum values during the first year of operation of the landfill (around 80,000 mg/L), gradually decreasing over subsequent years to less than 5000 mg/L. The concentration of ammonium, however, has not decreased, presenting values of up to 2000 mg/L. When feasible, recirculation can greatly decrease the organic matter content of the leachate to values of 1500-1600 mg COD/L. Applying anaerobic treatment to leachates with a COD between 11,000 and 16,000 mg/L, removal efficiencies of 80-88% were obtained for organic loading rates of 7 kg COD/m3d. For leachates with lower COD (4000-6000 mg/L), the efficiency decreased to around 60% for organic loading rates of 1 kg COD/m3d. Applying coagulation-flocculation with iron trichloride or with aluminium polychloride, it was possible to reduce the non-biodegradable organic matter by 73-62% when treating old landfill leachate (COD: 4800 mg/L, BOD5: 670 mg/L), also reducing turbidity and colour by more than 97%. It is likewise possible to reduce the non-biodegradable organic matter that remains after biological treatment by adsorption with activated carbon, although adsorption capacities are usually low (from 15 to 150 mg COD/g adsorbent). As regards ammonium nitrogen, this can be reduced to final effluent values of 5 mg/L by means of nitrification/denitrification and to values of 126 mg/L by stripping at pH 12 and 48 h of stirring.

Kinetic models based in biomass components for the combustion and pyrolysis of sewage sludge and its compost

In the present work, pyrolysis and combustion of the sewage sludge (fresh and composted) have been simulated using five fractions: low stability organic compounds, hemicellulose, cellulose, lignin-plastic, and inorganic compounds. Thermal behavior and kinetic parameters (pre-exponential factor and apparent activation energy) of the main components of the sludge are similar to those reported for hemicellulose, cellulose, and lignin present in lignocellulosic biomass. Comparing non-isothermal thermogravimetric analysis data obtained from fresh and composted sewage sludge, it is possible to measure the efficiency of the composting process. Most of the biodegradable matter is volatized in a temperature range from 150 °C to 400 °C. Non-biodegradable organic matter volatilizes between 400 °C and 550 °C. In both, fresh and composted sludges, oxygen presence increases the mass loss rate at any temperature, but differences between pyrolysis and combustion are focused in two clearly defined ranges. At low temperature (200–350 °C), mass loss is related with a volatilization process. At higher temperature (350–550 °C), mass loss is due to slow char oxidation (oxidative pyrolysis).

Decomposition of Acid Dye by TiO2 Thin Films Prepared by the Sol−Gel Method

Textile plants exhaust a great deal of water and generate a great deal of wastewater with high color contents, high suspended solids, and dissolved organics. To meet increasingly stringent environmental regulations, many technologies are used to remove toxic nonbiodegradable organic matters from the wastewaters. In this study, TiO2 thin films coated on glass bottles for use as photocatalytic reactors to decompose dye in aqueous solutions were prepared by the sol−gel method, followed by coating, drying, and calcination. An experimental design methodology was adopted to screen the most important factors and to search for the optimal preparation conditions. According to the Plackett−Burman design, the alcohol-to-titanium ratio, the acid-to-titanium ratio, and the sol−gel reaction time were found to be the most important variables that might affect the final TiO2 film performance in terms of dye decomposition efficiency. The maximum dye decomposition efficiency was found, by the simplex method, to be 49.2% under 4-W UV illumination for 6 h.

Performance evaluation of physicochemical processes for biologically pre-treated livestock wastewater

The use of a combination of biological and physicochemical methods is a promising technique to reduce highly concentrated pollutants in livestock wastewater: firstly, biodegradable organic matters, nitrogen and a part of phosphorus should be removed in a biological treatment process and then residual non-biodegradable organic matters, color and phosphorus be eliminated by physicochemical methods. In this study, therefore, the integrations of chemical coagulation, activated carbon adsorption, Fenton oxidation and ozonation were evaluated to provide an appropriate post-treatment process for biologically pre-treated livestock wastewater. With applying a single method such as coagulation and Fenton oxidation, a yellowish brown color and COD still remained. According to the experimental result, the quality of treated wastewater including color was enough to be discharged after chemical coagulation followed by ozonation or Fenton oxidation process. Among these, ozonation was the most effective technology for decolorization. Neither simple biological nor physicochemical process provides an adequate treatability for the sufficient depletion of organics and decolorization when treating livestock wastewater. Considering only the removal efficiency, the integration of Fenton oxidation and ozonation would be an efficient alternative as a post-treatment.

A respirometric method for characterising the organic composition and biodegradation kinetics and the temperature influence on the biodegradation kinetics, for a mixture of sludge and bulking agent to be co-composted

A respirometric method was set up to study kinetics of biological reactions involved in the treatment of organic wastes––sludge mixed with pine barks––by composting. Oxygen consumption rates of this type of mixture were monitored during 10–20 days, using a 10 l respirometric cell kept at constant temperature and moisture. Oxygen consumption kinetics were modelled and organic matter composition was characterised as biomass, easily-biodegradable, slowly-biodegradable and non-biodegradable organic matter. The influence of temperature on kinetics was tested. Results show that this respirometric method is a useful tool for the characterisation of solid organic matter biodegradability and for the modelling of the biological kinetics of the composting process.

Fenton oxidation process control using oxidation-reduction potential measurement for pigment wastewater treatment

The Fenton oxidation process was applied as a pretreatment process to degrade non-biodegradable organic matters in pigment wastewater. It was necessary to continuously measure the fluctuating concentration of organics in the pigment wastewater and to determine the amount of Fenton’s reagent required to oxidize the organics. Batch and continuous flow tests were used to evaluate the relationship between the concentration of organics (CODCr) and the amount of Fenton’s reagent required to achieve a sufficient oxidation of the organics. On-line measurements of the oxidation-reduction potential (ORP) value in the batch and continuous flow tests showed that the maximum ORP values were highly related to the organic concentrations (expressed as CODCr) and the Fenton’s reagent dosage (expressed as H2O2 concentration). The empirical equation was [CODCr]=8808+0.494[H2O2]-14.6ORP. A control program of Fenton’s reagent dosage based on the empirical equation was applied to control of a pilot scale Fenton oxidation process using ORP measurement. The concentration of organics predicted with the control program well agreed with the observed concentration of organics in the pigment wastewater. The variation of the effluent organics concentration of the controlled Fenton oxidation process was significantly reduced compared to that of a process without the control system. These results suggested that the control system of Fenton’s reagent dosage using ORP measurement would be applicable to the Fenton oxidation process for efficient pretreatment of pigment wastewater.

Removal of non-biodegradable organic matter from landfill leachates by adsorption

Leachates produced at the La Zoreda landfill in Asturias, Spain, were recirculated through a simulated landfill pilot plant. Prior to recirculation, three loads of different amounts of Municipal Solid Waste (MSW) were added to the plant, forming in this way consecutive layers. When anaerobic digestion was almost completed, the leachates from the landfill were recirculated. After recirculation, a new load of MSW was added and two new recirculations were carried out. The organic load of the three landfill leachates recirculated through the anaerobic pilot plant decreased from initial values of 5108, 3782 and 2560 mg/l to values of between 1500 and 1600 mg/l. Despite achieving reductions in the organic load of the leachate, a residual organic load still remained that was composed of non-biodegradable organic constituents such as humic substances. Similar values of the chemical oxygen demand (COD) were obtained when the landfill leachate was treated by a pressurised anoxic–aerobic process followed by ultrafiltration. After recirculation through the pilot plant, physico-chemical treatment was carried out to reduce the COD of the leachate. The pH of the leachate was decreased to a value of 1.5 to precipitate the humic fraction, obtaining a reduction in COD of about 13.5%. The supernatant liquid was treated with activated carbon and different resins, XAD-8, XAD-4 and IR-120. Activated carbon presented the highest adsorption capacities, obtaining COD values for the treated leachate in the order of 200 mg/l. Similar results were obtained when treating with activated carbon, the leachate from the biological treatment plant at the La Zoreda landfill; in this case without decreasing the pH.

Aerobic purification of dairy wastewater in batch reactors: kinetic study of the influence of a pre-storage stage without aeration in the degradation of organic matter and ammonium consumption by nitrification

Six tests were carried out delaying the air intake in order to determine the influence of a pre-storage stage (between 0 and 48 h) in organic matter removal and ammonification processes. The kinetic model proposed by Quiroga & Sales predicted successfully the total and soluble COD profiles. The maximum consumption rates were reached in tests with 0 and 30 h without initial aeration. There was no advantage in pre-storage times higher than 30 h, as the non-biodegradable organic matter increased. Concerning ammonium consumption in nitrification, the adjustment to Quiroga & Sales model demonstrated kinetics with an order varying between zero and one. This change in the reaction order was associated to an inhibition due to free ammonia. The experimental data adapted themselves fairly well to the proposed kinetic model.

Characteristics of organic matter as indicators of pollution from small‐scale livestock and nitrate contamination of shallow groundwater in an agricultural area

AbstractThe main purpose of this study was to examine the hydrogeochemical factors leading to nitrate contamination of shallow groundwater in an agricultural area. Another purpose was to identify relationships between variations in organic matter levels (as estimated by the BOD and COD parameters) of groundwater that transports effluent from small‐scale livestock holdings. Major cations, anions, BOD and COD of organic matter and total coliforms were analysed. It was found that groundwaters beneath cultivated areas and areas carrying livestock had higher concentrations of calcium, nitrate and chloride than did freshwater. Above all, the nitrification process increased concentrations of nitrate. Nitrate levels were depressed in some places where the groundwater was low in dissolved oxygen. Groundwaters affected by livestock activities showed high concentrations of organic matter (BOD, COD) and high microbial concentrations (as indicated by total coliforms). The COD/BOD ratio increased in the downward direction. It was inferred that this was due to the faster loss of easily biodegradable organic matter compared with non‐biodegradable organic matter proceeding away from a discharge. Accordingly, it is possible to trace effluent in a small area back to a point source by monitoring the COD/BOD ratio of groundwater. Copyright © 2003 John Wiley & Sons, Ltd.

Utilization of a bioluminescence toxicity assay for optimal design of biological and physicochemical wastewater treatment processes

AbstractA comprehensive laboratory investigation was conducted to test the feasibility of employing biological and physicochemical treatment processes for complex wastewaters discharged by several chemical industries. Results obtained during this study indicated that the wastes contain a fraction of toxic and nonbiodegradable organic matter, which limits the implementation of a conventional biological treatment process for the combined wastewater stream.Toxicity, as measured by a bioluminescence assay (Microtox), served as a valuable tool to assess biological treatability of various waste sources, with the aim to select an economically feasible and environmentally acceptable treatment/management program for an industrial park. Toxicity values served as quantitative indices for the establishment of baseline data of removability potential, defined either by biodegradation or carbon adsorption. This removability data enabled identification of problematic waste sources, which are only partially biodegradable and/or possess considerable toxicity.Further investigation of the problematic waste streams focused on the evaluation of activated carbon adsorption characteristics, using toxicity balances instead of traditional chemical determinations. This method could be successfully employed to yield simultaneously both adsorption characteristics and an assessment of the impact of the treated effluent on biota in receiving waters. © 1994 by John Wiley & Sons, Inc..

Development of a Pretreatment Program to Improve Biological Treatability of High Strength and Toxic Industrial Wastewater

A biological treatment process has been suggested as the main treatment stage for a high (organic) strength industrial wastewater stream, discharged by several chemical industries within a large industrial park. Treatability studies have indicated that the wastes contain a fraction of toxic and non-biodegradable organic matter, which limits the implementation of a conventional biological treatment process for the combined wastewater stream. Therefore, an in-plant control program including waste segregation and process-specific pretreatments is proposed. A protocol that enables selection of waste streams amenable to biological treatment and identification of problematic streams requiring pretreatment is presented and demonstrated. It includes simplified laboratory procedures used for chemical and toxicological characterization of source streams originating in various processes. The results can be used for the development of a pretreatment program for problematic waste streams, based upon local small-scale solutions.

Disinfection By‐product Formation and Control by Ozonation and Biotreatment

There is increasing interest in using ozone in water treatment because it is a strong disinfectant and is able to oxidize the precursors of some disinfection by‐products (DBPs). However, ozonation itself produces DBPs, like aldehydes and ketones, and increases the concentration of bacterial nutrients by converting nonbiodegradable organic matter to more biodegradable compounds. In this study it was found that biotreatment of ozonated waters provided additional removal of precursors of total trihalomethanes, total haloacetic acids, chloropicrin, and total organic halides. Aldehydes are easily biodegradable. Piloting is recommended to determine site‐specific ozone dosages and trade‐offs in the formation of bromate and ozone DBPs and in the oxidation of chlorine DBP precursors.

Influence of microbiological activity in granular activated carbon filters on the removal of organic compounds

In order to show the influence of bacterial activity in GAC filters on the removal of organic matter, experiments were carried out with diluted aqueous solutions of biodegradable and of non-biodegradable compounds under sterile and non sterile conditions. Productions of CO 2 show clearly that the bacterial activity can lead to a complete elimination of the biodegradable solute and to a partial microbiological regeneration of the adsorbent. By its influence on the competitive adsorption, the biological removal of biodegradable compounds leads to an increase of GAC adsorptive capacities for the non-biodegradable organic matter.

An ion exchange process to recover nutrients from sewage

After lengthy laboratory evaluation of resin selectivity towards the ionic species present in municipal sewage effluent (chloride, sulphate, phosphate, bicarbonate, ammonium, etc.), a process was developed for the recovery of nutrients by ion exchange. It comprises two exchange resin columns in series, containing Clinoptilolite and a porous type I quaternary anion resin with scavenger properties. Together, they remove eutrophic species to acceptable levels and filter residual suspended matter and partially adsorb non-biodegradable organic matter. The resins are regenerated by 0.6 M NaCl from which a slow release, economically valuable fertilizer, MgNH 4PO 4 · 6H 2O, is recovered by stripping and precipitation. After minor corrections, the regenerant solutions can be recycled. The results of more than one year of uninterrupted operation of a fully automatic pilot plant, comprising one column for each resin and operated in a discontinuous mode, are described. Further results from a three column system, which provided the data for the design of a 240 m 3/d demonstration plant, are also presented.