Suspended Chemical Oxygen Demand Research Articles

Exploring the potential of thermophilic anaerobic co-digestion between agro-industrial waste and water hyacinth: operational performance, kinetic study and degradation pathway.

Anaerobic co-digestion (co-AD) of agro-industrial waste, namely, palm oil mill effluent (POME) and sugarcane vinasse (Vn), with water hyacinth (WH) as co-substrate was carried out in two separate Anaerobic Suspended Growth Closed Bioreactors (ASGCBs) under thermophilic (55°C) conditions. The highest chemical oxygen demand (COD) and soluble COD reduction in co-AD of POME-WH (78.61%, 78.86%) is slightly higher than co-AD of Vn-WH (75.75%, 78.24%). However, VFA reduction in co-AD of POME-WH (96.41%) is higher compared to co-AD of Vn-WH (85.94%). Subsequently, biogas production peaked at 13438mL/day values and 16122mL/day for co-AD of POME-WH and Vn-WH, respectively. However, the methane content was higher in the co-AD of POME-WH (72.04%) than in the co-AD of Vn-WH (69.86%). Growth yield (YG), maximum specific substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) are higher in co-AD of POME-WH, as supported by the higher mixed liquor volatile suspended solids (MLVSS) and COD reduction efficiency compared to co-AD of Vn-WH. However, methane yield ([Formula: see text]) reported in the co-AD of POME-WH and Vn-WH are 0.2748 and 0.3112 L CH4/g CODreduction, respectively, which suggests that WH is a more suitable co-substrate for Vn compared to POME.

Filter based on sugar cane bagset for the treatment of wastewater from car washers in the city of Ambato, Ecuador

The effects of the oil industry continue to cause damage today. For example, car washers and their components still pollute sewage. This work assesses the efficiency of an artisan filter made of sugarcane bagasse, sand, crushed brick, and pumice stone. The research was carried out in the Chemistry Laboratory of the Faculty of Civil and Mechanical Engineering of the Technical University of Ambato, Ecuador, and as effluent, wastewater from a small car washing machine was used. To prove the efficiency of the filter and its limitations, the variation index in different parameters of this water was measured for 31 days, such as total solids, total suspended solids, BOD5 (biological oxygen demand), COD (chemical oxygen demand), pH, oils and fats, turbidity and TPH (total petroleum hydrocarbons). The preliminary results showed a significant improvement in the treated effluent's quality, especially in turbidity, TPH, total suspended solids, and pH.

Influence of urban runoff pollutant first flush strength on bioretention pollutant removal performance.

Bioretention is commonly used for runoff pollution control. The first flush strength of pollutants can affect bioretention performance. To examine the influence of the first flush strength on bioretention performance, bioretention columns filled with garden soil as the main media were established. Activated carbon and water treatment residuals (WTR) were added and compared for their ability to enhance phosphorus removal. Waste edible fungus culture medium (WEFCM) as a carbon source was also explored. When WEFCM was used as a carbon source instead of wood chips, total nitrogen (TN) removal increased from 60.83 ± 21.22 to 62.21 ± 16.43%, but chemical oxygen demand (COD) leaching was observed. WTR was better able than activated carbon to enhance phosphorus removal (87.97 ± 8.87 vs. 81.66 ± 9.27%) without impacting TN removal. NH4+-N removal increased with increasing first flush strength, but there was no trend for suspended solids (SS), COD, TN, or total phosphorus. First leaching phenomenon in bioretention outflow was proposed in this study. A low first leaching was observed in the outflow when the inflow had a uniform pollutant mass (i.e., no first flush) because of media leaching. A weak first leaching outflow was observed for SS and COD when they were present at strong first flush inflow.

Characterisation of Laboratory Wastewater for Planning Wastewater Treatment Plants in a University Campus in Indonesia

Numbers of parameters are referenced to determine the characteristics of wastewater. Biodegradability andtoxicity are determined based on the biochemical oxygen demand (BOD) to chemical oxygen demand (COD)ratio. Contaminant monitoring in wastewater is an important consideration in choosing among alternativewaste management systems. Information relating to wastewater parameters can be used to improve theefficiency and effectiveness of wastewater treatment plants (WWTP). This research focused on identifyingparameter conditions and classifying the biochemical oxygen demand (BOD) to chemical oxygen demand(COD) ratio of laboratory wastewater at the University of XYZ, Indonesia. Sampling of laboratory wastewaterfrom two faculties or Department in the University of XYZ the Faculty of Agricultural Technology and theFaculty of Pharmacy, was carried out using a grab sampling method. The wastewater quality parametersof temperature, pH, turbidity, total suspended solids (TSS), COD, BOD, and heavy metals were observedand the results obtained were compared with quality standards contained in Regulation of Environmentand Forestry Ministry No. 5, 2014. Wastewater characterisation was then identified based on the results ofBOD/COD calculations. The results showed that the quality parameters of pH, BOD, COD, TSS and totaldissolved solids (TDS) in laboratory wastewater exceeded the quality standards set. The BOD/COD ratioof wastewater taken from the laboratory of the Faculty of Agricultural Technology was 0.3 and for thePharmacy Faculty was 0.4, indicating that both were biodegradable. The wastewater treatmentrecommendation was a combination of physical (biofilter) and biological (phytoremediation) methods.The results of this investigation were used as considerations for the construction of a wastewater treatmentplant (WWTP) at the University of XYZ which would meet both aesthetic and environmental requirements.

Spatio-temporal characterization of nutrient and organic pollution along with nutrient-chlorophyll-a dynamics in the Geum River

River water pollution is one of the biggest environmental challenges in the world. Therefore, it is imperative to assess the spatial and temporal variability of surface water quality to manage water resources from pollution. This study aimed to identify spatio-temporal variations of Geum River surface water quality and the factors that influence it. Summer monsoon, land-use land-cover (LULC), and weirs are dominant factors determining the dynamics of river water quality. Empirical analysis showed that total phosphorus (TP), total nitrogen (TN), biological oxygen demand (BOD), and chemical oxygen demand (COD) had positive linear functional relations with the agricultural and built-up cover but negative linear relations with forest cover. The results showed that the total suspended solids (TSS), chlorophyll-a (CHL-a), TP, and COD levels were higher in the summer than in any other season. On the other hand, total nitrogen (TN) and electrical conductivity (EC) levels were lower during summer in the river due to the dilution effect. Pollutant-transport theory shows that TSS acts as a TP carrier (R2 = 0.83, p < 0.001). The empirical model suggested that TP (R2 = 0.76, p < 0.001) was the better predictor for CHL-a compared to TN (R2 = 0.13, p < 0.001) as well as showed strong P-limitation based on TN:TP ratios. The high average WQI values of the Geum River (except for S01 and S02) show a higher pollution level, indicating its unsuitability for drinking, irrigation, and industrial usage. Our results suggest that industrial and domestic sewage treatment and agricultural diffuse pollution control could improve the Geum river water quality.

Influence of Digested Sludge Conditioning on the Dewatering Processes and the Quality of Sludge Liquid

Abstract To increase the dewatering effect, sewage sludge should be properly prepared before dewatering. Sludge conditioning is a process whereby sludge solids are treated with chemicals or various other means to improve dewatering characteristics of the sludge by reducing the specific resistance and compressibility of the sludge. The aim of the research was to determine the possibility of increasing the efficiency of sewage sludge dewatering by applying chemical agents and ultrasonic field. Some parameters, such as suspension, chemical oxygen demand (COD), phosphorus and ammonium nitrogen content in sludge supernatant, were also analysed. Digested sludge belonged to the group of hardly dewatered sludge, its capillary suction time (CST) was of high value (2639 s). The lowest CST value (88.5 s) was obtained for the unsonicated sludge prepared only with PIX 113 at a dose of 7.0 mg/g d.m. Both the dose and the type of chemicals used, as well as the time of sonication, had an impact on the changes occurring in sludge properties. The increase in mechanical dewatering efficiency was obtained by using a combination of methods applied for sludge preparation, where the sonication of sludge was used at the preliminary stage and followed by dosing chemical substances. This resulted in the reduction of sludge final hydration and changes of other parameters. In addition, combined action of PIX 113 and Zetag 8180 allowed to reduce the content of suspended solids and COD in sludge supernatant.

Improving Quality of Water from Murchison Bay using Clay from Chelel, Kapchorwa District, Ugandao

Pollution resulting from increased human activities is threatening Lake Victoria, its effects are characterized by eutrophication, high turbidity, pH, iron(II) concentration and chemical oxygen demand (COD). In this study we have investigated the effect of Fe-montmorillonite clay from Chelel on turbidity, pH, concentration of iron, total suspended soils, total nutrients and COD of water sampled from Murchison bay watershed of Nakivubo channel south of Kampala. Varying amounts of clay powder was vigorously stirred with water samples for 5 minutes, filtered using Whitman paper at ambient temperatures. The optimum concentration of clay of 0.4gl-1 was found to produce 73.5+ 2% fall in COD indicating elimination of microbes and organic waste. The pH of water became 6.3+ 0.2 showing that impurities had been bound to clay. The turbidity of filtrate dropped to 15.7+ 0.3NTUshowing that clarity of water was improved by adsorption of suspended solids to clay minerals. The concentration of iron(II) fell from 3.7 + 0.3 to 2.5+ 0.2mgl-1 indicating fairly high extent of heavy metal removal from Murchison bay (MB) waters. The TSS and nutrients in MB water also decreased greatly when clay was stirred with water at ambient temperatures. The available data can be relied on to recommend use of this clay in treatment of waste water and/or sewage from Kampala. Further studies on combined use of clays with alums, zeolites and/or lime need to be carried out.

Improving Quality of Water from Murchison bay Using Clay from Chelel, Kapchorwa District, Uganda

Pollution resulting from increased human activities is threatening Lake Victoria, its effects are characterized by eutrophication, high turbidity, pH, iron(II) concentration and chemical oxygen demand (COD). In this study we have investigated the effect of Fe-montmorillonite clay from Chelel on turbidity, pH, concentration of iron, total suspended soils, total nutrients and COD of water sampled from Murchison bay watershed of Nakivubo channel south of Kampala. Varying amounts of clay powder was vigorously stirred with water samples for 5 minutes, filtered using Whatman paper at ambient temperatures. The optimum concentration of clay of 0.4 gL-1 was found to produce 73.5+2% fall in COD indicating elimination of microbes and organic waste. The pH of water became 6.3+ 0.2 showing that impurities had been bound to clay. The TSS and nutrients in MB water also decreased greatly when clay was stirred with water at ambient temperatures. The available data can be relied on to recommend use of this clay in treatment of waste water and/or sewage from Kampala. Further studies on combined use of clays with alums, zeolites and/or lime need to be carried out.

Gaining deeper insights into the bioflocculation process occurring in a high loaded membrane bioreactor used for the treatment of synthetic greywater

In the present study, a high loaded membrane bioreactor (HL-MBR) operated at a hydraulic retention time (HRT) of 1.5 h, and three different sludge retention times (SRTs) in the range of 0.5–2 days, was used for the treatment of synthetic greywater. The chemical oxygen demand (COD) removal efficiency of the system was in the range 87–89% at all SRTs. Bioflocculation efficiency (defined as the percentage of suspended COD in the concentrate stream), COD bio-oxidation, total extracellular polymeric substances (EPS), tightly bound (TB) EPS and the ratio of EPS protein (EPSp) to carbohydrate (EPSc) increased when SRT was increased from 0.5 to 2 days. Sludge supernatant soluble microbial products (SMP) increased with increase in SRT from 0.5 to 2 days, while the effluent SMP was negligible. Particle size distribution analyses revealed a bimodal distribution at an SRT of 0.5 days, and normal distributions at other SRTs. Furthermore, depending on the value of the F/M ratio, different SRTs in the range of 0.5–2 days had either positive or negative effects on the mean particle size. Linear correlation analyses were performed using the data obtained during both transient and steady-state operations of the HL-MBR system. TB-EPS and EPSp showed strong correlations with the biofloccultaion efficiency, whereas loosely bound (LB) EPS correlated with soluble COD removal. TB-EPS and EPSc had negative correlations with the energy recovery potential of the system. The trend of change of parameters affecting membrane fouling intensity with SRT suggested that, in the range studied, the lowest rate of membrane fouling would be expected at SRT of 0.5 days.

Treatment of palm oil mill effluent (POME) by coagulation flocculation process using peanut–okra and wheat germ–okra

Coagulation–flocculation has been proven as one of the effective processes in treating palm oil mill effluent (POME), which is a highly polluted wastewater generated from palm oil milling process. Two pairs of natural coagulant–flocculant were studied and evaluated: peanut–okra and wheat germ–okra. This research aims to optimize the operating parameters of the coagulation flocculation process in removing turbidity, total suspended solid and chemical oxygen demand (COD) from POME by using a central composite design in the Design Expert® software. Important parameters such as operating pH, coagulant and flocculant dosages were empirically determined using jar test experiment and optimized using response surface methodology module. Significant quadratic polynomial models were obtained via regression analyses (R2) for peanut–okra (0.9355, 0.9534 and 0.8586 for turbidity, total suspended solids and COD removal, respectively) and wheat germ–okra (0.9638, 0.9578 and 0.7691 for turbidity, total suspended solids and COD removal, respectively). The highest observed removal efficiencies of turbidity, total suspended solids and COD (92.5, 86.6 and 34.8%, respectively, for peanut–okra; 86.6, 87.5 and 43.6%, respectively, for wheat germ–okra) were obtained at optimum pH, coagulant and flocculant dosages (pH 11.6, 1000.1 mg/L and 135.5 mg/L, respectively, for peanut–okra; pH 12, 1170.5 mg/L and 100 mg/L, respectively, for wheat germ–okra). The coagulation flocculation performance of peanut–okra and wheat germ–okra were comparable to each other. Characterizations of the natural coagulant–flocculant, as well as the sludge produced, were performed using Fourier transform infrared, energy-dispersive X-ray spectroscopy and field emission scanning electron microscope. More than 98% of water was removed from POME sludge by using centrifuge and drying methods, indicating that a significant reduction in sludge volume was achieved.

Treatment efficiency of fish processing wastewater in different types of biological reactors

Fish processing technologies generate a significant amount of organic waste, both solid and liquid. Fish wastewater (FWW), if untreated or ineffectively treated, poses a threat to the aquatic environment.We investigated efficiency of different types of bioreactors with fixed and moving beds in the treatment of wastewater from fish processing. Pollution levels in raw effluents reached 260–660 mg O2 · dm−3 for BOD5, 450–950 mg O2 · dm−3 for suspended chemical oxygen demand (SCOD), 16.5–23 mg dm−3 for PO43-, and 10–18 mg dm−3 for NH4+. It was typical wastewater such as leachate and wastewater after fish processing. The models of bioreactors (on a laboratory scale) identified ring fixed bed reactors (RFBR) as the most efficient under efficient aeration. Average reduction of COD and BOD5 in RFBR was 44–80%, and 72–77% respectively, and for nutrients, it ranged from 16 to 34% for PO43- and reached 42% for NH4+. The other experimental bioreactors were significantly less effective. The application of FRBR in wastewater treatment from fish processing would allow effective reduction of organics pollutants and nutrients concentration in treated effluents.

Toxicity evaluation of textile dyeing effluent and its possible relationship with chemical oxygen demand

Textile dyeing wastewater was the focus of much research because of its adverse effect on aquatic biota. In the present research, textile dyeing influent and effluent samples were collected from four textile dyeing wastewater treatment plants (TDPs) in Guangdong province, China, and their conventional indicators and toxicity were examined to reveal relationships. The relationship between toxicity and chemical oxygen demand (COD) was clearly established at individual TDPs. Results indicated the highest removal efficiencies of 94.4%, 90.6%, 91.9%, 94.6%, 92.8% and 97.5% for TOC, mixed-liquor volatile suspended solids (MLVSS), COD, ammonia nitrogen (NH3-N), total phosphorus (TP) and colour, respectively. The primary clarifier used in TDP3 and TDP4 was beneficial for removing macromolecular organic substances, and membrane filtration and sedimentation basin employed at TDP1 and TDP2, respectively, helped to remove toxic substances. Toxicity to V. fischeri or D. subspicatus was found to be related to certain conventional indicators such as TOC, COD, TP, colour, and MLVSS, and was positively correlated with COD in different textile dyeing effluents (R2 > 0.84). It was recommended that the relationship between toxicity and COD in wastewater should be established individually at each plant. Therefore, this study could be useful in providing suggestions for guiding effluent management when no toxicity experiments were conducted.

High-frequency monitoring reveals seasonal and event-scale water quality variation in a temporally frozen river

Potential influences of climate change on water quality, riverine suspended sediments, nitrogen and organic matter loads in temporally frozen rivers, which have ice-covered flow and snow-affected basins, are poorly understood. However, before being able to understand potential future changes, the impact of ice and snow needs to be investigated more thoroughly for years which were hydrologically different. We investigated seasonal and event scale concentration-discharge (C-Q) dynamics of total suspended solids/turbidity, nitrate-N (NO3-N) and chemical oxygen demand (COD), which is indicative of the amount of organic matter in river water. In particular, the influence of ice cover, contrasting spring thaw, and soil frost conditions on intra-annual fluxes and the C-Q response of the three solutes are detected based on over four years of hourly data. Seasonally flow-weighted suspended solids and NO3-N concentrations were at their highest in either the autumn or spring thaw, but COD concentrations were the highest each year in autumn. NO3-N and COD levels typically decreased during winter. The ice-covered river water was less turbid compared to open-channel water at an equivalent river discharge likely due to in-stream factors. Storms during the freshet period introduced flushing of organic matter and suspended solids. The ratio of organic matter yield to water yield was similar each freshet and was independent of the amount of precipitation as snow or soil frost status. The freshet NO3-N yield per water yield was higher during the years with a thick snowpack and the consequent thawed soil compared to a year with soil frost and minor snowpack. 91 storm events studied revealed differences and similarities in storm dynamics in between the three variables. Anti-clockwise hysteresis was most common for the variables, with turbidity peaking faster than the COD or NO3-N concentration in most of the storms. Snowmelt storms showed highly variable C-Q responses inbetween the variables. However, spring thaw-related COD concentration peaks abated more slowly compared to turbidity or NO3-N. NO3-N showed a strong dilution pattern during several autumn storms during an extremely wet year, indicating limited N sources for flushing from the catchment. As a result, the flow-weighted mean NO3-N concentration was not the largest during the year of largest water yield instead which was true for suspended solids and COD. We found no evidence that warmer winters with precipitation as rain instead of snow would increase suspended sediment, organic matter and NO3-N load at entire winter-spring season or annual timescales.

Coagulant from Leucaena leucocephala for Chromium Removal

This research investigated the effectiveness of leucaena leucocephala as a natural coagulant for chromium removal. Leucaena leucocephala is a permanent non-climbing shrub tree which is wild and abundant in Malaysia and commonly known as petai belalang. Coagulation experiment using jar test were performed where the effect of coagulant dosage and pH were examined. The parameters investigated were suspended solid (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity and chromium content. The optimum of leucaena leucocephala coagulant dosage for removal of suspended solid, turbidity, COD, BOD and Chromium is at range 400-600 mg/L which yielded 45, 31.4, 38.5, 27.5 and 4.05% removal respectively. While the optimum pH is at pH 2-4 (acidic) which give 33.3, 26.8, 33.75, 31.4 and 14.06% removal of suspended solid, COD, BOD, turbidity and chromium content respectively. It is concluded that the leucaena leucocephala showed tremendous potential for chromium removal.

Dosage and pH optimization on stabilized landfill leachate via coagulation-flocculation process

Treatment on the generated landfill leachate is crucial as it can cause serious toxicological effects and environmental hazards, particularly when the unfavorable contaminants are left accumulated for a long period of time. The purpose of this study was to determine the optimum coagulant dosage of polyaluminium chloride (PAC) in selected dosage ranges (2250-4500 mg/L) and to analyse the ideal pH of leachate sample (pH 3-10). PAC was tested on stabilized leachate taken from Simpang Renggam Landfill Site (SRLS), by investigating the percentage removals of five significant parameters, which were suspended solids, chemical oxygen demand (COD), ammonia, and heavy metals (iron (Fe) and chromium (Cr)). The removal efficiency was determined by a series of experiments using jar test. From the obtained results, it was found that 3750 mg/L and pH 7 were the optimum conditions for PAC dosage and sample pH, respectively. The conventional optimization test showed satisfactory results for suspended solids, COD, Fe, and Cr at 95%, 53%, 97%, and 79% respectively, but had low removal on ammonia at 18%. It can be concluded that the coagulation-flocculation process has the potential to be applied as a primary treatment for stabilized landfill leachate in Malaysia.

Adsorption of colour, TSS and COD from palm oil mill effluent (POME) using acid-washed coconut shell activated carbon: Kinetic and mechanism studies

The disposal of palm oil mill effluent (POME) without proper treatment before being discharged into natural water sources has become undesirable because of high concentration of suspended solid (SS), oil and grease (O&G), chemical oxygen demand (COD) and biological oxygen demand (BOD). This study investigated the feasibility of removing colour, total suspended solid (TSS) and COD using acid-washed coconut shell based activated carbon (CSAC) through the evaluation of the adsorption uptake as well as the adsorption kinetics and mechanism. The percentage removal of colour, TSS and COD from POME onto CSAC were 61%, 39%, 66%, respectively achieved within 48 hours of contact time. The kinetic models studied were pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich models. The intra-particle diffusion (IPD) model was studied to interpret the adsorption diffusion mechanism. The adsorption of colour, TSS and COD onto CSAC were best interpreted by the PSO model, and well fitted by the Elovich model. The IPD and Boyd plots indicated that IPD and film diffusion controlled the adsorption of colour, TSS and COD onto the CSAC.

ASPECTS REGARDING THE ELECTROCOAGULATION APPLICATIONS IN THE WATER AND WASTEWATER TREATMENT

Electrocoagulation (EC) has been known for over a century. Applications in industry as water and wastewater treatment processes were adapted for the removal of suspended solids, organic compounds, COD (Chemical oxygen demand), BOD (biochemical oxygen demand), metallic and non-metallic pollution. The main advantage in EC technology is the fact that it works without the addition of chemical products. The DC current between metallic electrodes immersed in the effluent is used as an energy source for this technique, which causes their dissolution. The effect of the main parameters, current density, treatment time, initial pH, temperature, electrode materials, conductivity and distance between the electrodes were investigated. According to the conclusion of the works published in recent years, the removal efficiencies of pollutants materials by EC process are very important.

Improvement and prediction of OSA system performance in sludge reduction through integration with thermal and mechanical treatment

The oxic-settling-anoxic (OSA) process is one of the sludge production reduction methods in the activated sludge process. In this method, sludge is stored in an anaerobic tank within the sludge return line before entrance into an aeration tank. Due to this method's flexibility in application to operating treatment plants and not being energy-consuming, its application is developing. In this research, the improvement of the OSA process is investigated via thermal and mechanical treatment in a sequencing batch reactor (SBR). A pilot-scale reactor and domestic wastewater are used. Sludge was subjected to high temperature in an anaerobic tank using a heat transformer and it was subjected to mechanical shear through mechanical mixing in the anaerobic tank. Different temperatures and voltages were tested. The OSA process reduced sludge production by 24% while the chemical oxygen demand (COD) removal rate decreased from 90% to 86%. Thermal treatment combined with the OSA process caused a maximum of 46% sludge production reduction. However temperatures above 90 °C are not recommended due to a high level of decrease in COD removal. Mechanical mixing in combination with the OSA process led to 34% sludge production reduction. The effluent quality is not affected by the OSA process itself but is slightly reduced by thermal treatment and mechanical mixing. Therefore, for reaching the maximum sludge reduction in OSA plus thermal and mechanical treatment it would be necessary to evaluate the effect of different sets of parameters on effluent quality beside the sludge reduction. For this purpose multi-layer perceptron artificial neural network models are developed to predict the effluent total suspended solids and COD removal efficiency as well as sludge production rate. The models perform well and would be useful tools in determining the optimal set of system operation parameters.

Mainstream partial nitritation and anammox in a 200,000 m3/day activated sludge process in Singapore: scale-down by using laboratory fed-batch reactor.

A laboratory fed-batch reactor has been used to study under controlled conditions the performance of partial nitritation/anammox for the 200,000 m(3)/day step-feed activated sludge process at the Changi Water Reclamation Plant, Singapore. The similarity of the concentrations of NH(4), NO(2), NO(3), PO(4), suspended chemical oxygen demand (sCOD), pH, and alkalinity (ALK) between the on-site process and laboratory reactor illustrates that the laboratory fed-batch reactor can be used to simulate the site performance. The performance of the reactor fed by primary effluent illustrated the existence of anammox and heterotrophic denitrification and apparent excessive biological phosphorus removal as observed from the site. The performance of the reactor fed by final effluent proved the presence of anammox process on site. Both the laboratory reactor and on-site process showed that higher influent 5-day biochemical oxygen demand/total nitrogen (BOD(5)/TN) (COD/TN) ratio increases the nitrogen removal efficiency of the process.

Gráfico de controle da média móvel exponencialmente ponderada: aplicação na operação e monitoramento de uma estação de tratamento de esgoto

RESUMO Este trabalho teve por objetivo avaliar o desempenho de uma estação de tratamento de esgoto através de cartas de controle de qualidade estatística da média móvel exponencialmente ponderada (MMEP). A estação de tratamento de esgoto estudada localiza-se no Município de Cascavel, Paraná, Os parâmetros avaliados foram o potencial hidrogeniônico (pH), sólidos sedimentáveis (SSed), sólidos suspensos totais (SST), demanda química de oxigênio (DQO) e a demanda bioquímica de oxigênio (DBO). As cartas MMEP acusaram que estação de tratamento de esgoto apresentou bom desempenho estatístico para o pH, sólidos suspensos totais, DQO e DBO e falhas para os sólidos sedimentáveis. As cartas de controle MMEP se apresentam como uma boa alternativa no monitoramento de estações de tratamento de esgoto.