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Suspended Solids (suspended + solid)

Distribution by Scientific Domains

Life Sciences	34%
Engineering	31%
Chemistry	27%

Kinds of Suspended Solids

volatile suspended solid

Selected Abstracts

Efficiency of permeable pavement systems for the removal of urban runoff pollutants under varying environmental conditions

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2010
Kiran Tota-Maharaj
Abstract Urban surface water runoff typically contains a high but variable number of pathogens, nutrients, and sediments that require removal before reuse. Permeable pavements can improve the water quality through interception, filtration, sedimentation, nutrient transformation, and microbial removal. There is currently insufficient scientific information available on the treatment efficiencies of permeable pavements combined with earth energy systems with regards to the removal of storm water pollutants such as nutrients, sediments, and microbial pollutants. This study evaluates the efficiency of 12 tanked combined systems during a medium-term study. The research assessed weekly the removal of the microbial indicators total coliforms, Escherichia coli, and fecal Streptococci, as well as the key nutrients ammonia-nitrogen, nitrate-nitrogen, and ortho-phosphate-phosphorus, and physical variables such as suspended solids and turbidity. Total coliforms, E. coli, and fecal Streptococci were removed by 98,99%. The ammonia-nitrogen and ortho-phosphate-phosphorus removal efficiencies were 84.6% and 77.5%, respectively. An analysis of variance indicated that the presence or absence of a geotextile did result in a very highly statistically significant difference (P < 0.001) with respect to the removal of both ammonia-nitrogen and ortho-phosphate-phosphorus. Suspended solids, turbidity, and biochemical oxygen demand were reduced by 91%, 82%, and 88%, respectively. These results indicate the potential of the proposed novel system in urban runoff pollutant removal and subsequent reuse of the treated water. © 2010 American Institute of Chemical Engineers Environ Prog, 2010 [source]

The effect of drawdown on suspended solids and phosphorus export from Columbia Lake, Waterloo, Canada

HYDROLOGICAL PROCESSES, Issue 5 2004
Mike Shantz
Abstract This study examines the effect of drawdown on the timing and magnitude of suspended solids and associated phosphorus export from a 12 ha reservoir located in an urbanized watershed in southern Ontario, Canada. Water level in Columbia Lake was lowered by 1·15 m over a 2-week period in November 2001. The total phosphorus (TP) concentrations ranged from 63 to 486 µg L,1 in Columbia Lake and 71 to 373 µg L,1 at its outflow. All samples exceeded the Provincial Water Quality Objective of 30 µg TP L,1. Outflow concentrations of suspended solids and TP increased significantly with decreasing lake level and were attributed to the resuspension of cohesive bottom sediments that occurred at a critical threshold lake level (0·65 m below summer level). Suspended solids at the outflow consisted of flocculated cohesive materials with a median diameter (D50) of c. 5 µm. Particulate organic carbon accounted for 8·5% of the suspended solids export by mass. A total mass of 18·5 t of suspended solids and 62·6 kg TP was exported from Columbia Lake, which represents a significant pulse of sediment-associated P to downstream environments each autumn during drawdown. The downstream impacts of this release can be minimized if the water level in Columbia Lake is lowered no more than 0·5 m below summer levels. Copyright © 2004 John Wiley & Sons, Ltd. [source]

The use of mangrove wetland as a biofilter to treat shrimp pond effluents: preliminary results of an experiment on the Caribbean coast of Colombia

AQUACULTURE RESEARCH, Issue 10 2001
Dominique Gautier
Abstract The potential benefit of integrating mangrove and shrimp farms to protect ponds against erosion, to enhance the productivity of supply water and also to treat pond effluents has been pointed out previously. Agrosoledad, a 286-ha shrimp farm located on the Caribbean coast of Colombia, was constructed behind a 1-km-wide mangrove area. Farm effluents are partially recirculated through a 120-ha mangrove wetland used as a biofilter. A 3-month study compared the concentrations of suspended solids and inorganic nutrients in the supply canal, the pond drainage and the biofilter. Suspended solids increased in pond drainage compared with supply water, but they were drastically reduced in the biofilter. In contrast, dissolved inorganic nitrogen and phosphorus concentrations were not different in supply water and pond drainage, but they increased in the biofilter because of the presence of a large marine bird community. Additionally, a significant decrease in dissolved oxygen and pH was observed in the biofilter. The study demonstrated the efficiency of the system to eliminate suspended solids from the effluent. However, nutrient dynamics showed that the possible use of mangrove wetlands as biofilters for effluent treatment will be less predictable than expected. [source]

Agitation requirements for complete solid suspension in an unbaffled agitated vessel with an unsteadily forward,reverse rotating impeller

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2007
Shuichi Tezura
Abstract Background: To develop a new type of solid,liquid apparatus, we have proposed the application of an agitation system with an impeller whose rotation alternates direction unsteadily, i.e., a forward,reverse rotating impeller. For an unbaffled agitated vessel fitted with this system, the suspension of solid particles in a liquid was studied using a disk turbine impeller with six flat blades. Results: The effects of the solid,liquid conditions and geometrical conditions of the apparatus on the minimum rotation rate and the corresponding impeller power consumption were evaluated experimentally for a completely suspended solid. The power consumption for a just suspended solid with this type of vessel was comparable with that for a baffled vessel with a unidirectionally rotating impeller, taking the liquid flow along the vessel bottom into consideration. Conclusion: Empirical relationships to predict the parameters of agitation requirements were found. A comparative investigation demonstrated the usefulness of the forward,reverse rotation mode of the impeller for off-bottom suspension of solid particles. Copyright © 2007 Society of Chemical Industry [source]

Acclimation Strategy of a Biohydrogen Producing Population in a Continuous-Flow Reactor with Carbohydrate Fermentation

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2006
Q. Ren
Abstract Poor startup of biological hydrogen production systems can cause an ineffective hydrogen production rate and poor biomass growth at a high hydraulic retention time (HRT), or cause a prolonged period of acclimation. In this paper a new startup strategy was developed in order to improve the enrichment of the hydrogen-producing population and the efficiency of hydrogen production. A continuously-stirred tank reactor (CSTR) and molasses were used to evaluate the hydrogen productivity of the sewage sludge microflora at a temperature of 35,°C. The experimental results indicated that the feed to microorganism ratio (F/M ratio) was a key parameter for the enrichment of hydrogen producing sludge in a continuous-flow reactor. When the initial biomass was inoculated with 6.24,g of volatile suspended solids (VSS)/L, an HRT of 6,h, an initial organic loading rate (OLR) of 7.0,kg chemical oxygen demand (COD)/(m3,×,d) and an feed to microorganism ratio (F/M) ratio of about 2,3,g COD/(g of volatile suspended solids (VSS) per day) were maintained during startup. Under these conditions, a hydrogen producing population at an equilibrium state could be established within 30,days. The main liquid fermentation products were acetate and ethanol. Biogas was composed of H2 and CO2. The hydrogen content in the biogas amounted to 47.5,%. The average hydrogen yield was 2.01,mol/mol hexose consumed. It was also observed that a special hydrogen producing population was formed when this startup strategy was used. It is supposed that the population may have had some special metabolic pathways to produce hydrogen along with ethanol as the main fermentation products. [source]

Efficiency of permeable pavement systems for the removal of urban runoff pollutants under varying environmental conditions

CMP wastewater management using the concepts of design for environment

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2002
Gordon C. C. YangArticle first published online: 20 APR 200
Application of design for environment (DfE) concepts to management of wastewater from chemical mechanical polishing (CMP) processes are presented in this paper. Today, DfE is a prevailing concept and is widely adopted by advanced nations in lieu of the traditional "command and control" approach to control waste and toxic emissions. Designing environmentally-benign processes and products is a new and challenging frontier for engineering professionals, including those in the semiconductor industry. An insatiable need for water and subsequent wastewater treatment has imposed a chilling effect on semiconductor industry growth. It was estimated that semiconductor producers consumed more than 5.523 × 108 m3 of water in 2000. Of this amount, CMP processes accounted for 40% of the total. The CMP tool market and CMP slurry market are estimated to have 36% and 29% annual growth rates, respectively between 2000 and 2005. Inevitably, a tremendous amount of waste slurry and post-CMP rinse water will be generated and have to be managed properly. CMP wastewater is characterized by its high content of suspended solids having sub-micron particle sizes, high turbidity, and high conductivity. Traditional wastewater treatment technologies, such as chemical coagulation/precipitation, do not work well for CMP wastewater, because it would generate a large volume of sludge, which might cause disposal problems in many countries, such as Taiwan. Therefore, utilizing pollution prevention principles in the design of CMP tools, development of new CMP slurries, and improved plant operations are necessary to minimize environmental damage. Reclamation of process water is also a common requirement in the semiconductor industry. To this end, several alternatives for source reduction of CMP wastewater and water reclamation are presented in this paper. [source]

The effects of continuous and pulsed exposures of suspended clay on the survival, growth, and reproduction of Daphnia magna

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2010
Sarah E. Robinson
Abstract Suspended sediments are a natural component of aquatic ecosystems, but anthropogenic activity such as land development can result in significant increases, especially after rain events. Continuous exposures of suspended clay and silt have been shown to affect growth and reproduction of Cladocera, leading to a decrease in population growth rate. The mechanism of clay toxicity in these filter-feeding organisms is clogging of the gut tract, resulting in decreased food uptake and assimilation. When placed in clean water, daphnids can purge clay from their gut and recover. In many surface waters, aquatic organisms experience episodic exposures of high concentrations of suspended solids driven by rain events. However, little is known about the consequences of pulsed exposures on individuals and populations. The objective of the present study was to characterize the effects of continuous and pulsed exposures of natural and defined clays on survival, growth, and reproduction of Daphnia magna. Two defined clays, montmorillonite and kaolinite, as well as clay isolated from the Piedmont region of South Carolina, USA, were used. Continuous exposures of clays elicited a dose dependent decrease in survival. Toxicity varied depending on clay source with montmorillonite,>,natural clay,>,kaolinite. Pulsed exposures caused a decrease in survival in a 24 h exposure of 734 mg/L kaolinite. Exposure to 73.9 mg/L also caused an increase in the time to gravidity, although there was not a corresponding decrease in neonate production over 21 d. No significant effects resulted from 12 h exposures even at 730 mg/L, almost 10 times the 24-h reproductive effects concentration. This suggests that exposure duration impacted toxicity more than exposure concentration in these pulsed exposures. Environ. Toxicol. Chem. 2010;29:168,175. © 2009 SETAC [source]

Fate of estrogens and xenoestrogens in four sewage treatment plants with different technologies,

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2008
Guang-Guo Ying
Abstract The fate and removal of the estrogens 17,-estradiol (E2), estrone (E1), and 17,-ethynylestradiol (EE2) and of the xenoestrogens bisphenol A (BPA), 4- tert -octylphenol (4- t -OP), 4-nonylphenol (4-NP), and nonylphenol mono- and diethoxylate (NPEO1 and NPEO2, respectively) were investigated in four South Australian sewage treatment plants (STPs; plants A,D) with different treatment technologies. The concentrations in the effluent from the two-year survey were similar to those reported in other studies. In the effluent, 4-NP, NPEO1, and NPEO2 had total concentrations up to 8 ,g/L, which were much higher than those of BPA and 4-t-OP. Estrone had the highest concentrations among the three estrogens, ranging between 13.3 and 39.3 ng/L, whereas the concentrations for E2 and EE2 varied between 1.0 and 4.2 ng/L and between 0.1 and 1.3 ng/L, respectively. The removal rates for the estrogens and xenoestrogens were variable but consistent with the plant performance parameters (biochemical oxygen demand, suspended solids, and ammonia). Considering all the estrogenic compounds analyzed in the present study, plant D, with a series of anaerobic and aerobic lagoons, was the least efficient of the four STPs in the removal of these compounds. The removal rates for 4-NP, NPEO1, and NPEO2 within the plants were 92% for plant A, with conventional activated sludge treatment; 80% for plant B, with two oxidation ditches; 70% for plant C, with three bioreactors; and 64% for plant D, with 10 lagoons in series. Comparatively, the removal of estrogens was lower, with rates ranging between 47 and 68% for E2 at the four plants. Both E1 and EE2 were more persistent during treatment, especially in plants C and D. [source]

The long-term fate of polychlorinated biphenyls in San Francisco Bay (USA)

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2004
Jay A. Davis
Abstract A simple one-box mass budget model is presented as a first step toward a quantitative understanding of the long-term fate of polychlorinated biphenyls (PCBs) in San Francisco Bay (USA). Sensitivity analysis indicated that the most influential input parameters were degradation half-life in sediment, Kow, outflow, average PCB concentration in sediment, and depth of the active sediment layer. Moderately influential parameters included organic carbon content of suspended solids, sediment burial mass transfer coefficient, and Henry's law constant. If external loading could be eliminated entirely, the mass of PCBs in the bay is predicted to drop to half of the present value in 20 years. The model predicts that sustained loading of 10 kg year,1 would prevent the total PCB mass in the bay from ever dropping below 10% of the present mass. With a sustained loading of 20 kg year,1, the model predicts that the total PCB mass would never fall below about 25% of the present mass. The half-lives in the bay for the individual PCB congeners evaluated in this report ranged from four years for PCB 18 to 30 years for PCB 194. [source]

In situ water and sediment toxicity in an agricultural watershed

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2004
Bryn M. Phillips
Abstract The Salinas River receives inputs from extensive farmlands before flowing into the Salinas River National Wildlife Refuge and the Monterey Bay National Marine Sanctuary (CA, USA). Previous monitoring using laboratory toxicity tests and chemical analyses identified toxic agricultural drain-water inputs in this system. Using caged daphnids (Ceriodaphnia dubia) and amphipods (Hyalella azteca), we investigated in situ toxicity at stations downstream from an agricultural drain relative to a reference station. A flow sensor indicated highly variable inputs from irrigation, and daily synoptic chemical analyses using enzyme-linked immunosorbent assay techniques demonstrated fluctuating concentrations of organophosphate pesticides. Test organism mortality in the field coincided with contaminant concentrations that exceeded chemical effect thresholds for the test species. Laboratory toxicity tests using C. dubia were comparable to results from field exposures, but tests with H. azteca were not. Laboratory exposures can be reasonable surrogates for field evaluations in this system, but they were less effective for assessing short-term temporal variability. Results from the field toxicity studies corroborated results of bioassessment surveys conducted as part of a concurrent study. Toxicity identification evaluations indicated that organophosphate pesticides caused toxicity to daphnids and that effects of suspended solids were negligible. [source]

Phase distribution of synthetic pyrethroids in runoff and stream water

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2004
Weiping Liu
Abstract Synthetic pyrethroids (SPs) are a group of hydrophobic compounds with significant aquatic toxicity. Their strong affinity to suspended solids and humic materials suggests that SPs in natural surface water are distributed in solid-adsorbed, dissolved organic matter (DOM)-adsorbed, and freely dissolved phases. The freely dissolved phase is of particular importance because of its mobility and bioavailability. In the present study, we used solid-phase microextraction to detect the freely dissolved phase, and we evaluated the phase distribution of bifenthrin and permethrin in stream and runoff waters. In stream water, most SPs were associated with the suspended solids and, to a lesser extent, with DOM. The freely dissolved phase contributed only 0.4% to 1.0%. In runoff effluents, the freely dissolved concentration was 10% to 27% of the overall concentration. The predominant partitioning into the adsorbed phases implies that the toxicity of SPs in surface water is reduced because of decreased bioavailability. This also suggests that monitoring protocols that do not selectively define the freely dissolved phase can lead to significant overestimation of toxicity or water-quality impacts by SPs. [source]

Effects of hydrogeomorphic region, catchment storage and mature forest on baseflow and snowmelt stream water quality in second-order Lake Superior Basin tributaries

FRESHWATER BIOLOGY, Issue 5 2003
Naomi E. Detenbeck
SUMMARY 1. In this study we predict stream sensitivity to non-point source pollution based on the non-linear responses of hydrological regimes and associated loadings of non-point source pollutants to catchment properties. We assessed two hydrologically based thresholds of impairment, one for catchment storage (5,10%) and one for mature forest (<50% versus >60% of catchment in mature forest cover) across two different hydrogeomorphic regions within the Northern Lakes and Forest (NLF) ecoregion: the North Shore [predominantly within the North Shore Highlands Ecological Unit] and the South Shore (predominantly within the Lake Superior Clay Plain Ecological Unit). Water quality samples were collected and analysed during peak snowmelt and baseflow conditions from 24 second-order streams grouped as follows: three in each region × catchment storage × mature forest class. 2. Water quality was affected by a combination of regional influences, catchment storage and mature forest. Regional differences were significant for suspended solids, phosphorus, nitrogen: phosphorus ratios, dissolved organic carbon (DOC) and alkalinity. Catchment storage was significantly correlated with dissolved silica during the early to mid-growing season, and with DOC, specific conductance and alkalinity during all seasons. Total nitrogen and dissolved nitrogen were consistently less in low mature forest than in high mature forest catchments. Catchment storage interacted with the influence of mature forest for only two metrics: colour and the soluble inorganic nitrogen : phosphorus ratio. 3. Significant interaction terms (region by mature forest or region by storage) suggest differences in regional sensitivity for conductance, alkalinity, total organic carbon, and colour, as well as possible shifts in thresholds of impact across region or mature forest class. 4. Use of the NLF Ecoregion alone as a basis for setting regional water quality criteria would lead to the misinterpretation of reference condition and assessment of condition. There were pronounced differences in background water quality between the North and South Shore streams, particularly for parameters related to differences in soil parent material and glacial history. A stratified random sampling design for baseflow and snowmelt stream water quality based on both hydrogeomorphic region and catchment attributes improves assessments of both reference condition and differences in regional sensitivity. [source]

Lake age and water level affect the turbidity of floodplain lakes along the lower Rhine

FRESHWATER BIOLOGY, Issue 3 2003
F. C. J. M. Roozen
SUMMARY 1. We sampled a set of 93 lakes situated in the floodplains of the lower River Rhine in search for morphometric and other factors that explain their variation in clarity. 2. Lakes with a drop in summer water level were less turbid at the time of sampling, mainly because of a lower concentration of inorganic suspended solids (ISS). 3. We also found that older lakes were more turbid than younger lakes and that this was largely because of an increase in phytoplankton. 4. Water clarity was positively related to lake depth and the presence of vegetation. 5. Model calculations indicated that the underwater light climate was strongly affected by chlorophyll and ISS, the latter being the dominant factor affecting Secchi depth. Dissolved organic carbon (DOC) was less important. 6. The high concentration of ISS suggests that intensive resuspension occurs in most of the lakes. Using a simple wave model, and assuming that vegetation protects sediments against resuspension, we could eliminate wind resuspension as an important process in 90% of the lakes, leaving resuspension by benthivorous fish as probably the most important factor determining transparency. 7. Chlorophyll a concentration showed a strong positive correlation to ISS concentration, suggesting that resuspension may also have a positive effect on phytoplankton biomass in these lakes. 8. In conclusion, in-lake processes, rather than river dynamics, seem to be driving the turbidity of floodplain lakes along the lower River Rhine. [source]

Numerical Modeling of Unsaturated Flow in Wastewater Soil Absorption Systems

GROUND WATER MONITORING & REMEDIATION, Issue 2 2003
Deborah N. Huntzinger Beach
It is common practice in the United States to use wastewater soil absorption systems (WSAS) to treat domestic wastewater. WSAS are expected to provide efficient, long-term removal of wastewater contaminants prior to ground water recharge. Soil clogging at the infiltrative surface of WSAS occurs due to the accumulation of suspended solids, organic matter, and chemical precipitates during continued wastewater infiltration. This clogging zone (CZ) creates an impedance to flow, restricting the hydraulic conductivity and rate of infiltration. A certain degree of clogging may improve the treatment of wastewater by enhancing purification processes, in part because unsaturated flow is induced and residence times are significantly increased. However, if clogging becomes excessive, the wastewater pond height at the infiltrative surface can rise to a level where system failure occurs. The numerical model HYDRUS-2D is used to simulate unsaturated flow within WSAS to better understand the effect of CZs on unsaturated flow behavior and hydraulic retention times in sandy and silty soil. The simulations indicate that sand-based WSAS with mature CZs are characterized by a more widely distributed flow regime and longer hydraulic retention times. The impact of clogging on water flow within the silt is not as substantial. For sand, increasing the hydraulic resistance of the CZ by a factor of three to four requires an increase in the pond height by as much as a factor of five to achieve the same wastewater loading. Because the degree of CZ resistance directly influences the pond height within a system, understanding the influence of the CZ on flow regimes in WSAS is critical in optimizing system design to achieve the desired pollutant-treatment efficiency and to prolong system life. [source]

The effect of drawdown on suspended solids and phosphorus export from Columbia Lake, Waterloo, Canada

The performance of constructed wetlands for, wastewater treatment: a case study of Splash wetland in Nairobi Kenya

HYDROLOGICAL PROCESSES, Issue 17 2001
Daniel Muasya Nzengy'a
Abstract The performance of a constructed wetland for wastewater treatment was examined for four months (December 1995 to March 1996). The study area, hereby referred to as the Splash wetland, is approximately 0·5 ha, and is located in the southern part of Nairobi city. Splash wetland continuously receives domestic sewage from two busy restaurants. Treated wastewater is recycled for re-use for various purposes in the restaurants. Both wet and dry season data were analysed with a view of determining the impact of seasonal variation on the system performance. The physical and chemical properties of water were measured at a common intake and at series of seven other points established along the wetland gradient and at the outlet where the water is collected and pumped for re-use at the restaurants. The physico-chemical characteristics of the wastewater changed significantly as the wastewater flowed through the respective wetland cells. A comparison of wastewater influent versus the effluent from the wetland revealed the system's apparent success in water treatment, especially in pH modification, removal of suspended solids, organic load and nutrients mean influent pH = 5·7 ± 0·5, mean effluent pH 7·7 ± 0·3; mean influent BOD5 = 1603·0 ± 397·6 mg/l, mean effluent BOD5 = 15·1 ± 2·5 mg/l; mean influent COD = 3749·8 ± 206·8 mg/l, mean effluent COD = 95·6 ± 7·2 mg/l; mean influent TSS = 195·4 ± 58·7 mg/l, mean effluent TSS = 4·7 ± 1·9 mg/l. As the wastewater flowed through the wetland system dissolved free and saline ammonia, NH4+, decreased from 14·6 ± 4·1 mg/l to undetectable levels at the outlet. Dissolved oxygen increased progressively through the wetland system. Analysis of the data available did not reveal temporal variation in the system's performance. However, significant spatial variation was evident as the wetland removed most of the common pollutants and considerably improved the quality of the water, making it safe for re-use at the restaurants. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Peracetic acid as an alternative wastewater disinfectant to chlorine dioxide

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002
S. Stampi
Aims: The aim of this study was to compare the efficiency of peracetic acid with that of chlorine dioxide in the disinfection of wastewater from a sewage treatment plant (serving about 650 000 inhabitants) that has been using peracetic acid as a disinfectant since 1998. Methods and Results: A total of 23 samplings were made, each consisting of three samples: from secondary effluent, effluent disinfected with 2 mg l,1 of peracetic acid and effluent disinfected with 2·2 mg l,1 of chlorine dioxide (contact time 20 min). For each sample, measurements were made of the heterotrophic plate count at 36°C, total and faecal coliforms, Escherichia coli, enterococci, pH, suspended solids and chemical oxygen demand (COD). During the first phase of the experiment the peracetic acid was seen to be less efficient than chlorine dioxide. To improve the disinfectant action a system of mechanical agitation was added which led to a greater efficiency in the inactivation of bacteria of faecal origin. Conclusions: Both products were found to be influenced by the level of microbial contamination, the amount of suspended solids and COD but not by the pH of the effluent before disinfection. The immediate mixing of the wastewater and disinfectant caused a greater reduction in enterococci. Significance and Impact of the Study: Since peracetic acid was seen to produce a high abatement of micro-organisms, it can be considered as a valid alternative to chlorine dioxide in the disinfection of wastewaters. [source]

Palm oil mill effluent pretreatment using Moringa oleifera seeds as an environmentally friendly coagulant: laboratory and pilot plant studies

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2006
Subhash Bhatia
Abstract This research paper covers the suitability of the coagulation,flocculation process using Moringa oleifera seeds after oil extraction as a natural and environmentally friendly coagulant for palm oil mill effluent treatment. The performance of M. oleifera coagulant was studied along with the flocculant KP 9650 in removal of suspended solids, organic components and in increasing the floc size. The optimum values of the operating parameters obtained from the laboratory jar test were applied in a pilot-scale treatment plant comprised of coagulation,flocculation and filtration processes. Pilot-scale pretreatment resulted in 99.7% suspended solids removal, 71.5% COD reduction, 68.2% BOD reduction, 100% oil and grease removal and 91% TKN removal. In pilot plant pretreatment, the percentage recovery of water was 83.3%, and 99.7% sludge was recovered after dewatering in a filter press. Copyright © 2006 Society of Chemical Industry [source]

Studies on internal and external water treatment at a paper and cardboard factory

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2003
Mamdouh M Nassar
Abstract The treatment of effluent from a paper/board factory that produced 280 tons of cardboard and consumed 1200 m3 of water per day was carried out. Wastewater analysis showed that the mill effluent contained 3000 mg dm,3 suspended solids, 1400 mg dm,3 COD (chemical oxygen demand) and 500 mg dm,3 BOD (biochemical oxygen demand). An internal treatment cycle is suggested that involves recirculation of paper-machine wastewater (white-water) and may be accomplished by installing a flotation saveall (fiber recovery) unit. This arrangement reduced fresh water use by about 90%, reduced fiber loss by 80,90%, and increased board production by 13%. An external treatment process for the effluent was assessed by conducting laboratory coagulation tests (alum, ferric chloride, ferrous sulfate, and polyelectrolyte) on the whole mill effluent. Oxidation of the mill effluent using calcium hypochlorite before discharging the effluent to a lagoon offers the benefits of killing the harmful bacteria and reducing the pollution load. Copyright © 2003 Society of Chemical Industry [source]

Characterization and modelling of denim-processing wastewaters for activated sludge

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2001
Derin Orhon
Abstract The study involved characterization of denim-processing wastewaters, mainly to generate the necessary experimental data for the modelling and evaluation of the activated sludge process. The striking feature of the wastewater quality was the excessive suspended solids content requiring effective removal before biological treatment. COD fractionation was, however, typical for a textile effluent in general, with a biodegradable fraction of 90%, a readily biodegradable COD ratio of 20%, a predominantly soluble slowly biodegradable fraction of 55,60% and negligible particulate inert COD. Hydrolysis was identified as the significant step in the biodegradation kinetics with rate coefficients quite specific to plant operation. Evaluation of the hydrolysis kinetics showed that the magnitude of the slowly biodegradable COD could be reduced with a higher hydraulic detention time, effectively improving the quality of the soluble effluent. © 2001 Society of Chemical Industry [source]

Development of a mechanistic model for biological nutrient removal activated sludge systems and application to a full-scale WWTP

AICHE JOURNAL, Issue 6 2010
Bing-Jie Ni
Abstract In wastewater treatment plants (WWTPs) the production of nitrite as an intermediate in the biological nutrient removal (BNR) process has been widely observed, but not been taken into account by most of the conventional activated sludge models yet. This work aims to develop a mechanistic mathematical model to evaluate the BNR process after resolving such a problem. A mathematical model is developed based on the Activated Sludge Model No.3 (ASM3) and the EAWAG Bio-P model with an incorporation of the two-step nitrification,denitrification, the anoxic P uptake, and the associated two-step denitrification by phosphorus accumulating organisms. The database used for simulations originates from a full-scale BNR municipal wastewater treatment plant. The influent wastewater composition is characterized using batch tests. Model predictions are compared with the measured concentrations of chemical oxygen demand (COD), NH -N, NO -N, NO -N, PO -P, and mixed liquid volatile suspended solids. Simulation results indicate that the calibrated model is capable of predicting the microbial growth, COD removal, nitrification and denitrification, as well as aerobic and anoxic P removal. Thus, this model can be used to evaluate and simulate full-scale BNR activated sludge WWTPs. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Modeling and simulation of the sequencing batch reactor at a full-scale municipal wastewater treatment plant

AICHE JOURNAL, Issue 8 2009
Bing-Jie Ni
Abstract In this work, we attempted to modify the Activated Sludge Model No.3 and to simulate the performance of a full-scale sequencing batch reactor (SBR) plant for municipal wastewater treatment. The long-term dynamic data from the continuous operation of this SBR plant were simulated. The influent wastewater composition was characterized using batch measurements. After incorporating all the relevant processes, the sensitivity of the stoichiometric and kinetic coefficients for the model was thoroughly analyzed prior to the model calibration. The modified model was calibrated and validated with the data from both batch- and full-scale experiments. Model predictions were compared with routine data in terms of chemical oxygen demand, NH4+ -N and mixed liquid volatile suspended solids in the SBR, combined with batch experimental data under different conditions. The model predictions match the experimental results well, demonstrating that the model is appropriate to simulate the performance of a full-scale wastewater treatment plant even operated under perturbation conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

STORM DISCHARGE, LOADS, AND AVERAGE CONCENTRATIONS IN NORTHWEST OHIO RIVERS, 1975,1995,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2001
R. Peter Richards
ABSTRACT: A computerized technique was developed to identify storm runoff episodes and calculate storm discharges, storm loads, and storm average concentrations for each event in datasets with up to 10,000 records. This technique was applied to four watersheds within the Lake Erie drainage basin and identified between 160 and 250 runoff events in each. Storm event loads and storm event mean concentrations were calculated for each runoff event for suspended solids, total phosphorus, soluble reactive phosphorus, nitrate, and total Kjeldahl nitrogen. The basic characteristics of the resulting data are described, as are systematic differences as a function of watershed size, seasonal differences, and trends over time. Many of the results of this study reflect the importance of nonpoint processes and improvements in agricultural best management practices in these watersheds. [source]

Flow regime determination in horizontal hydrotransport using non-intrusive acoustic probes

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008
Katherine Albion
Abstract A variety of flow regimes may be observed in the hydrotransport of solids. Maintaining a consistent operation requires rapid detection of any change in flow regime. The objective of this study was to develop reliable, non-intrusive, and on-line methods for flow regime detection in a hydrotransport pipe based on acoustic measurements. Slurries were transported in a 0.05 m diameter stainless steel hydrotransport pipe. Acoustic measurements were recorded by microphones along the length of the horizontal pipe. Two flow regimes were observed: suspended solids flow and flow over settled solids. Cycle and frequency analyses of the acoustic signals provided reliable identification of these flow regimes. Plusieurs régimes d'écoulement peuvent être observés dans le transport hydraulique des solides. Le maintien d'un fonctionnement consistant nécessite la détection rapide de tout changement dans le régime d'écoulement. L'objectif de cette étude est de développer des méthodes fiables, non intrusives et en continu pour la détection des régimes d'écoulement dans une conduite de transport hydraulique reposant sur des mesures acoustiques. Les suspensions ont été transportées dans une conduite de transport hydraulique en acier inoxydable de 0,05 m de diamètre. Les mesures acoustiques ont été enregistrées par des microphones le long de la conduite horizontale. Deux régimes d'écoulement ont été observés : l'écoulement de solides suspendus et l'écoulement au-dessus des solides déposés. Les analyses de cycle et de fréquence des signaux acoustiques fournissent une identification fiable de ces régimes d'écoulement. [source]

The use of mangrove wetland as a biofilter to treat shrimp pond effluents: preliminary results of an experiment on the Caribbean coast of Colombia

Treatment of Skim Latex Serum Using Gas Sparged Ultrafiltration

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2005
Harunsyah
Abstract The major pollutants from a natural rubber processing factory have high organic content and emit an offensive smell due to the biodegradation of the organic matter. In latex concentrate factories, the main sources of effluent are the skim latex serum and washings from all process equipment. This paper presents an application of membrane technology that involves gas sparging for the treatment of skim latex serum. A semi-pilot-scale system using a PVDF vertical tubular membrane (MWCO 100,000) was installed as the experimental setup. Nitrogen gas was bubbled vertically upwards at flowrates ranging from 300 to 500 ml/min. Results obtained thus far show that gas sparging has increased the permeate flux between 1.37% and 146.34% compared to non-gas sparged conditions. In terms of permeate quality, the reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 83%, 95%, 67%, 77%, 51%, 74%, respectively, for the gas-sparged condition. Under non gas-sparging conditions, reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 92%, 96%, 67%, 72%, 60%, 75%, respectively. [source]

Advanced monitoring of high-rate anaerobic reactors through quantitative image analysis of granular sludge and multivariate statistical analysis

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009
J.C. Costa
Abstract Four organic loading disturbances were performed in lab-scale EGSB reactors fed with ethanol. In load disturbance 1 (LD1) and 2 (LD2), the organic loading rate (OLR) was increased between 5 and 18.5 kg,COD,m,3,day,1, through the influent ethanol concentration increase, and the hydraulic retention time decrease from 7.8 to 2.5 h, respectively. Load disturbances 3 (LD3) and 4 (LD4) were applied by increasing the OLR to 50 kg,COD,m,3,day,1 during 3 days and 16 days, respectively. The granular sludge morphology was quantified by image analysis and was related to the reactor performance, including effluent volatile suspended solids, indicator of washout events. In general, it was observed the selective washout of filamentous forms associated to granules erosion/fragmentation and to a decrease in the specific acetoclastic activity. These phenomena induced the transitory deterioration of reactor performance in LD2, LD3, and LD4, but not in LD1. Extending the exposure time in LD4 promoted acetogenesis inhibition after 144 h. The application of Principal Components Analysis determined a latent variable that encompasses a weighted sum of performance, physiological and morphological information. This new variable was highly sensitive to reactor efficiency deterioration, enclosing variations between 27% and 268% in the first hours of disturbances. The high loadings raised by image analysis parameters, especially filaments length per aggregates area (LfA), revealed that morphological changes of granular sludge, should be considered to monitor and control load disturbances in high rate anaerobic (granular) sludge bed digesters. Biotechnol. Bioeng. 2009;102: 445,456. © 2008 Wiley Periodicals, Inc. [source]