Amount Of COD Research Articles

Simple Models for the Control of Photo-Fenton by Monitoring H2O2

AbstractIt has been demonstrated that Photo-Fenton process is feasible for the remediation of wastewater containing multiple organic pollutants. In order to promote its industrialization, control strategies have to be defined and tested. The objective of the present work is to describe a mathematical equation that fits the amount of COD abated regarding the dose of H

Diffuse pollution from livestock production in China

With economic development and living standard improvement, livestock and poultry production has grown up rapidly, also has become the leading source of pollution in vast rural areas in China. The estimated annual loss amount of COD, BOD, NH3-N from manure in 2001 is 7. 28 million ton, 4.99 million ton and 1.32 million ton, respectively. The COD loss amount from manure is close to the sum of COD from industrial and domestic wastewater. Because animal waste and wastewater can enter water bodies from spills or breaks of waste storage structures (due to accidents or excessive rain), and non-agricultural application of manure to cropland, this contamination has resulted in quality degradation of surface and underground drinking water supplies. Areas with concentrated livestock operations are showing elevated nutrients and organic pollutant contents in surface waters. This widespread contamination of water has prompted governments at various levels to adopt regulations and measures to control the spreading of livestock pollution.

Influence of the size of membrane foulants on the filterability of WWTP-effluent

The application of membrane filtration for the polishing of wastewater treatment plant (wwtp) effluent is more and more widely used. However, fouling problems are still not well understood. In order to investigate the role of particles in dead-end ultrafiltration of wwtp-effluent, Roorda studied the influence of pre-filtrated wwtp-effluent on the filterability. In addition this research investigates the relation between the filterability of the different fractions in the wwtp-effluent and the amount of organic foulants in these fractions. The results show a relation between the filterability and supra-dissolved particles in the fractions < 0.45 and < 0.2 microm. The amount of COD, colour, proteins and polysaccharides in these fractions are found of minor importance. A significant increase in filterability is found between the fractions < 0.2 and < 0.1 microm as well as a significant decrease in amount of polysaccharides. It is suggested that an essential feature in understanding membrane fouling during ultrafiltration of wwtp-effluent is to investigate the influence of supra-dissolved particles on the filterability as well as the influence of the amount of organic foulants (total organic carbon, proteins, polysaccharides, colour and humic substances) on the reversibility.

Influence of process conditions and membrane/particle interaction in NF of wastewaters

The clean environment concept and the demand of decreasing the use of fresh water make it important to reuse wastewaters from industry. One of the industries producing great amounts of wastewater containing fairly low amounts of COD is the pulp and paper industry. These produced effluent waters can be cleaned by membrane filtration so that they can be reused on site. By using ultrafiltration, a water clean enough for most places in the mill can be produced. But for the more demanding places nanofiltration has to be used in order to get a micro-particle free water. Since the volumes of water to be filtered can be in the order of cubic meters per second a high flux is important. The wastewaters in the pulp and paper industry, like surface waters, contain organic degradation products from trees that are of a hydrophobic nature. These molecules easily aggregate and foul the membranes if the membranes are hydrophobic or if the process conditions are favourable to fouling. In the studies reported here the process conditions, the membrane materials and the interactions of hydrophobic molecules in the wastewater or surface water with different kinds of nanofiltration membranes were investigated. The influence of high shear on critical flux was investigated. Adsorption was to be minimised by choosing the least fouling hydrophilic membranes (characterisation by contact angle). Different measurements were made on the waste-waters like TOC, UV-absorption, conductivity, hardness, SUVA index, etc. The results showed that the best nanofiltration fluxes for long periods of time were achieved using very high shear cross-flow modules. Besides on high shear, the study focused on finding hydrophilic membranes and on trying either to use pretreatment to remove the foulants before filtration or on using some kind of adsorbing filtration aid during the filtration. In some cases fibers naturally formed the filtration aid.

The Influence of Start-Up Strategies on the Performance of an Anaerobic Baffled Reactor

The start-up and performance of two 10 litre anaerobic baffled reactors (ABR), both of which contained eight compartments and were operated under mesophilic conditions (35°C), were investigated. Two start-up strategies were evaluated: one with a constant hydraulic retention time (HRT) and a stepwise doubling of the organic feed strength (ABR 1), the other with a constant organic strength (4 g l−1 chemical oxygen demand COD, as sucrose) coupled to a systematic halving of HRT (ABR 2). The final desired baseline conditions were a feed strength of 4 g COD−1 and 20 hours HRT. The best stability and COD removal was demonstrated by the reactor started at a long retention time (ABR 2). The biomass (volatile suspended solids, VSS) lost from each reactor was greater in ABR 1 than in ABR 2 (200 g compared to 100 g after 140 days), and it was hypothesised that in ABR 1 low retention time and channelling controlled biomass washout, whereas in ABR 2 washout appeared to be caused by gas mixing. Microbial floc sizes were measured and found to decrease initially in most cases, but increased over time and after 270 days the average floc sizes were 152 and 185 µm in ABR 1 and 2 respectively. The largest flocs were found in compartments 4 to 6 for both reactors, and it is proposed that this was due to a combination of low gas production and low but significant amounts of COD. SEM and TEM photographs suggest that the population of methanogenic bacteria altered from primarily Methanosarcina-like organisms at the front where high substrate levels and low pH were present, to Methanosaeta-like bacteria at the rear of the reactors where there were low substrate levels and neutral pH conditions.

Treatment of slaughterhouse effluent using an anaerobic filter

A pilot-scale study was conducted to evaluate the treatment performance of an upflow anaerobic filter (AF) on a slaughterhouse effluent. The effluent flow rate through the AF was changed for seven treatment trials, and performance was evaluated by the amount of COD removed. The COD removals ranged between 37% and 77% and were related to the reciprocal of the hydraulic retention time, in accordance with the Young and McCarty empirical model. The COD removals in this study were less in comparison to other similar AF studies, and factors attributed to this included low solids retention time and reactor design. The average removals of total coliforms, fecal coliforms, fecal streptococci, and standard plate count densities through the AF were 29%, 18%, 95%, and 65% respectively. The average methane content of the biogas was 71%. The methane yields ranged between 0.19 and 0.23 (m3 STP/kg COD removed). Tracer results showed that effluent flow through the AF was predominately completely mixed. Key words: anaerobic filter, slaughterhouse effluent, media, indicator microorganisms, treatment, methane.

Post Treatment of Anaerobic Effluent Using Sequencing Batch Reactors

A 150ℓ field unit and two 7.5ℓ laboratory scale sequencing batch reactors (SBRs) were used to polish edible oil refinery wastewater pretreated by attached film anaerobic reactors. SBRs performed well with respect to COD and suspended solids removal. At a loading rate of less than 2 kg COD/m3-d more than 90% COD removal efficiency was achieved. Solids settling was good with SVI generally less than 160. The system showed stability under large variations of organic loading and operating conditions. A significant amount of COD was removed during the long filling and anoxic period.

Sequential Anaerobic and Aerobic Treatment of Kraft Pulping Wastes

A study of sequential anaerobic and aerobic treatment was conducted with combinations of kraft evaporator condensate (KEC) and caustic extraction (CE) stage bleaching effluent. In addition to conventional measures of treatment efficiency, the transformations and removal of sulfur compounds from the KEC and changes in molecular size fraction of organic carbon and organic chlorine were measured. A large fraction of the BOD in the combined waste could be removed in the anaerobic stage at loadings of up to at least 15 kg COD/m3-d. The overall process produced an effluent with &amp;lt;30 mg/l BOD and SS and with varying amounts of COD, depending on the CE fraction being treated. Fractional removals of organic carbon and COD were approximately equal and were significantly greater than that of organic chlorine. Removal efficiencies were higher for the low molecular weight fraction. One third of the influent sulfur was removed as H2S gas in the anaerobic stage. The remaining sulfur was largely oxidized to sulfate in the aerobic stage, with nearly complete elimination of odors.

The internal crack in an extended or compressed plate: Its geometric characteristics

The Muskhelishvili closed-form solution of an infinite plate containing an internal crack and submitted to either simple tension or compression was used for evaluating the exact shape of the deformed crack. The orientation of the crack-axis relative to the loading axis of the plate varied parametrically to cover all possible orientations. Using the already established fact that the deformed crack becomes an ellipse, whose principal axes change orientation from those of the unloaded crack, the dependence of the length of the deformed crack and its COD variation was plotted in terms of the angle β of inclination and the load level of the plate. It was shown that, while the purely extended crack remains symmetric to its initial axis and shrinks, the purely compressed crack presents a concordant correspondence of its deformed lips, which are closing creating a quasi-disappearance of the crack. Introduction of any amount of shear immediately introduces a discordant correspondence between respective points of the crack lips and contributes to their overlapping. Then, some amount of COD must be introduced by extending the crack in order to assure open lips of the crack. On the other hand, the length of the deformed crack is always smaller than its initial length for pure extension, whereas, for compression, it is always larger than the initial length. However, introduction of shear causes an increase of the final crack length, which may even overpass the initial crack length for some stress levels. Finally, phenomena of stick-slip and popping appear with loading when the dominant shear straining or the combination of compression and shear make the lips of the crack overlap and hinder a smooth propagation of the crack by loading. Experimental evidence with caustics in specimens under plane stress or plane strain corroborated the phenomena described by the theory.

Processing of Cod and Haddock Viscera: 1. Laboratory Experiments

Annually, large amounts of cod and haddock viscera (minus livers) are discarded by the fishing industry. The chemical composition of this offal makes it a possible raw material for production of additives to animal feeds. Various processes that would lead to a method of production of such preparations were investigated. Autolysis of fresh viscera in the presence of sodium nitrite as a preservative was found most attractive. Optimum conditions for this process were established and various methods of drying these autolysates were investigated.