Maximum Total Suspended Solids Research Articles

Insight into the pollution characteristics of road and roof runoff in Changsha, China

Non-point source pollution from rainwater runoff presents a serious challenge for urban water management in many cities undergoing urbanization and experiencing climate change. To alleviate water resource conflicts in Changsha, China, this study comprehensively evaluated the pollution characteristics and first flush effect (FFE) of runoff from asphalt roads and colored steel plate roofs under seven rainfall events in April-May 2022. The runoff was collected and purified using bioretention ponds. The results showed that the peak runoff pollutant concentrations occurred within the first 20min of runoff generation and then decreased to relatively stable levels, with maximum total suspended solids (TSS) concentration and chemical oxygen demand (CODCr) reaching 873.5 and 207.32mg/L, respectively, for road runoff and 162 and 73.31mg/L for roof runoff, respectively. The main pollutants were TSS and CODCr, followed by ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), total phosphorus (TP), and nitrite nitrogen (NO2--N). Concentrations of pollutants and FFE for roof runoff were lower than those for road runoff. Road runoff had a more obvious FFE for TP and NH4+-N, whereas the roof runoff showed the presence of TP and NO3--N. An important implication is that treating the first 30% of surface runoff from rainfall events with long antecedent dry days or high rainfall amounts is necessary to improve water quality before discharge or utilization. The study also found that road and roof runoff, after treatment with bioretention ponds, exhibit good water quality, thus, allowing their use as reclaimed water or for miscellaneous purposes in urban areas. Overall, this study provides useful information for designing management measures to mitigate runoff pollution and reuse in Changsha.

Printing ink wastewater treatment using combined hydrodynamic cavitation and pH fixation.

Printing ink wastewater (PIW) carries a heavy load of pollutants, the composition of which makes treatment difficult, especially when trying to minimize the pollution load. According to the latter, the present study aims to investigate PIW treatment with different various methods and to determine the maximum color, COD (chemical oxygen demand) and TSS (total suspended solids) removal. First, hydrodynamic cavitation (HC) was tested and the effect of hydrogen peroxide dosage (0-10gL-1), and pH (3, 5, 8, 10) was examined concerning the removal of PIW initial COD concentrations 4000 and 8000mgL-1. Removal was high (more than 81%) only at pH 5 in HC reactor. The second method involved treatment with separate pH fixation of the undiluted PIW (COD 17000mgL-1, actual pH 8±0.2). This treatment, maximized removals, reaching reduction of the initial values more than 91%, at pH 5. Finally, PIW was treated with a combination of the above methods, leading to 93-97% removals for 8000mgL-1 PIW treatment and 97-99% for 17000mgL-1 PIW respectively. Process cost calculations showed that the latter method is an effective and affordable treatment method for PIW streams, while toxicity tests of the treated PIW showed substantial toxicity reduction.

Enhanced biogas production and substrate degradation through the intermittent operation of modified upflow anaerobic sludge blanket-static granular bed reactor series.

In the present study, the performance of a modified upflow anaerobic sludge blanket (MUASB) reactor-static granular bed reactor (SGBR) series in intermittent operation was analyzed for the treatment of synthetic wastewater. The reactor series was operated with a hydraulic retention time (HRT) of 24 h. The maximum chemical oxygen demand (COD) removal and biogas production of the reactor series obtained during the intermittent operation were 99 ± 0.29% and 0.529 ± 0.03 m3 /kg CODdigested , respectively. One-way analysis of variance (ANOVA) indicated a significant difference in biogas production during continuous and intermittent operations, whereas the COD removal was similar. Intermittent operation of the reactor series yielded a 56.05% increase in biogas production when compared with the continuous operation. The reactor series was maintained stable throughout the operational period. The maximum total suspended solids (TSS) removal and total nitrogen (TN) removal of the reactor series during the intermittent operation were 91.67% and 72.37%, respectively. Intermittent operation of the reactor series can be considered advantageous because of the reduced operational cost and enhanced biogas production in addition to COD removal. PRACTITIONER POINTS: Intermittent operation of MUASB-SGBR series in terms of COD removal is evaluated. COD removal of reactor series was similar in intermittent and continuous operation. Biogas production in intermittent operation was superior to continuous operation. Reactor series performance is also compared with continuous operation using one-way ANOVA.

High suspended solids removal of Indian drain water with a down-scaled Dissolved Air Flotation (DAF) for water recovery. Assessing water-type dependence on process control variables

The Barapullah drain crosses through New Delhi, India, and transports millions of cubic meters of stormwater, municipal sewage and industrial sewage to the Yamuna River. Seasonal variations and ambiguous annual discharges cause 20-fold fluctuations in hydraulic flows, pollutants type and concentration. Furthermore, New Delhi is among the most densely populated areas on the planet, with limited surface area and high water stress. Dissolved Air Flotation (DAF) units are known to be highly compact, robust, and an efficient suspended solids separation technology that enables further water recovery in a treatment train. Thus, a down-scaled column DAF was designed and used to determine the total suspended solids removal efficiencies, under different influent conditions. Three influents that resemble the Barapullah drain seasonal variations in composition, and a fourth that imitates the feed of DAF when located after an anaerobic bioreactor were tested. A total of 60 batch DAF experiments were completed and used to assess seven independent control variables for DAF operation, which are influent Total Suspended Solids (TSS), pH, temperature, DAF particles residence time, white water pressure, coagulants and flocculants concentration, and coagulation and flocculation time. Results showed that the down-scaled DAF could be steered from low to high removal efficiencies, comparable to full-scale systems. Maximum TSS removal varied between 92 and 96%. The effect and statistical relevance of the different performance variables on the measured separation efficiencies depended on the influent type. All variables, except temperature and pH, had a significant performance effect with a p-value below 0.1, for at least one influent. Pressure had a positive effect on separation efficiency, due to its importance in bubble formation. Moreover, the down-scaled DAF system had low removal efficiency for particles with spherical shapes, and diameters below 10 µm. Based on the high TSS removal for all tested influents, and the effect of the studied control variables, a full-scale DAF could efficiently remove the suspended solids of the Barapullah drain. The unit robustness for different flows and pollutant concentrations, and small footprint, show DAF suitability as part of a treatment train for water recovery, in densely populated areas.

Particle size distribution modeling and kinetic study for coagulation treatment of tannery industry wastewater at response surface optimized condition

The presence of considerable amounts of Total Suspended Solids (TSS) in wastewater streams can pose a severe threat to aquatic and human life. A high level of TSS will increase water temperature at an alarming rate and decrease dissolved oxygen levels. This study aims to remove TSS from raw tannery wastewater using an active coagulating protein extracted from Moringa oleifera (MO) seeds. The process variables such as, coagulant dosage and pH are varied to test the potential of the coagulant extracted using NaCl and KCl salt solutions, for TSS removal from tannery wastewater. The results show that the NaCl extracted coagulant could effectively remove 89.87% of TSS whereas the KCl extracted coagulant eliminated 76.23% of TSS, at the optimum condition of 40 mL coagulant dosage and 7 pH. The assessment of coagulation rate parameters using differential method of analysis reveals that at optimum condition, the TSS reduction process obeys second order kinetics with a rate constant 3.556 × 10– 5 (mg/L)– 1 min– 1. The volume distribution of suspended solids in raw wastewater is fitted with a log-normal distribution model and Gaussian distribution model. From the magnitude of the coefficient of determination (R2) and Akaike information criterion (AIC) of the Gaussian model (R2 = 0.6864 and AIC = 3.89), it is concluded that the Gaussian model is better than the log-normal distribution model (R2 = 0.4708 and AIC = 6.31) for explaining the volumetric distribution of suspended particles. The numeric distribution of suspended solids in raw wastewater is explained well by the variable β model (R2 = 0.668) rather than the power law model (R2 = 0.196). The 3D response surface plot indicates that maximum TSS removal can be achieved at an optimal condition of 40 mL coagulant dose and 7 pH. The quadratic model developed for the treatment process utilizing the NaCl extracted coagulant shows better response prediction ability (R2 = 0.8118) when compared to the model built for the KCl extracted coagulant (R2 = 0.7911). Both the model equations have a p-value less than 0.05 which indicates that the proposed models are statistically significant. The elliptical contours for TSS removal using NaCl extracted coagulant demonstrate the significant interactions between the process variables. This study exhibited the applicability of MO seed extract for real-time tannery wastewater treatment.

Optimal Planning of Low-Impact Development for TSS Control in the Upper Area of the Cau Bay River Basin, Vietnam

Recently, an increase in impervious area induced by the process of urbanization has significantly affected the quantity and quality of urban surface runoff. Among the pollutants of the storm flow, total suspended solids (TSS) are an extremely important cause of water quality deterioration. This paper aims to use the integrated nondominated sorting genetic algorithm (NSGA II)–Storm Water Management Model (SWMM) method to find optimal Low-Impact Development (LID) plans which ensure maximum TSS load reduction and minimum total relative cost. Green roofs, permeable pavements, and tree boxes with fixed parameters and unit costs were considered for seeking optimal planning alternatives in the Cau Bay river basin. The optimization process yielded a cost–effectiveness curve, which relates cost of LID implementation with its corresponding TSS reduction efficiencies. The advantage of the optimization approach was clarified when, with a defined cost of LID implementation, there was a significant difference in TSS reduction efficiencies between the optimal and non-optimal alternatives. The increase in return periods of rainfall patterns not only resulted in a reduction in the TSS removal efficiencies of LID practices at the outfall of the study area, but also spatially changed in terms of the TSS removal efficiencies of the sub-catchments. The return period of the rainfall patterns utilized for LID design should not exceed 2 years. The simulation–multi-optimization approach facilitates integration of LID practice plans into the urban infrastructure master plans in Vietnam.

Prediction of Algal Chlorophyll-a and Water Clarity in Monsoon-Region Reservoir Using Machine Learning Approaches

The prediction of algal chlorophyll-a and water clarity in lentic ecosystems is a hot issue due to rapid deteriorations of drinking water quality and eutrophication processes. Our key objectives of the study were to predict long-term algal chlorophyll-a and transparency (water clarity), measured as Secchi depth, in spatially heterogeneous and temporally dynamic reservoirs largely influenced by the Asian monsoon during 2000–2017 and then determine the reservoir trophic state using a multiple linear regression (MLR), support vector machine (SVM) and artificial neural network (ANN). We tested the models to analyze the spatial patterns of the riverine zone (Rz), transitional zone (Tz) and lacustrine zone (Lz) and temporal variations of premonsoon, monsoon and postmonsoon. Monthly physicochemical parameters and precipitation data (2000–2017) were used to build up the models of MLR, SVM and ANN and then were confirmed by cross-validation processes. The model of SVM showed better predictive performance than the models of MLR and ANN, in both before validation and after validation. Values of root mean square error (RMSE) and mean absolute error (MAE) were lower in the SVM model, compared to the models of MLR and ANN, indicating that the SVM model has better performance than the MLR and ANN models. The coefficient of determination was higher in the SVM model, compared to the MLR and ANN models. The mean and maximum total suspended solids (TSS), nutrients (total nitrogen (TN) and total phosphorus (TP)), water temperature (WT), conductivity and algal chlorophyll (CHL-a) were in higher concentrations in the riverine zone compared to transitional and lacustrine zone due to surface run-off from the watershed. During the premonsoon and postmonsoon, the average annual rainfall was 59.50 mm and 54.73 mm whereas it was 236.66 mm during the monsoon period. From 2013 to 2017, the trophic state of the reservoir on the basis of CHL-a and SD was from mesotrophic to oligotrophic. Analysis of the importance of input variables indicated that WT, TP, TSS, TN, NP ratios and the rainfall influenced the chlorophyll-a and transparency directly in the reservoir. These findings of the algal chlorophyll-a predictions and Secchi depth may provide key clues for better management strategy in the reservoir.

Evaluation of Sequencing Batch Reactor Performance for Petrochemical Wastewater Treatment

Sequencing batch reactor (SBR) technology has found many applications in industrial wastewater treatment in recent years. The aim of this study was to determine the optimal time for a cycle of the sequencing batch reactor (SBR) and evaluate the performance of a SBR for petrochemical wastewater treatment in that cycle time. The reactor was operated with a suspended biomass configuration under aerobic conditions. Carbon removal and operating parameters such as pH, temperature and dissolved oxygen (DO) were monitored during the wastewater treatment. The SBR was run at different cycle times and amongst the cycle times tested, the best performance was obtained with a 7 h cycle time composed of a fill time of 15min, reaction of 6 h, settling of 30 min, and withdrawal of 15 min. The SBR with the determined cycle time was used to study the treatment of wastewater with various organic loading rates (12.88 gr COD/L.d, 18.02 gr COD/L.d and 31.39 gr COD/L.d). The SBR performance was evaluated by chemical oxygen demand (COD), total solids (TS) total suspended solids (TSS) removal efficiencies. During the shock loading tests, the maximum COD, TS and TSS removal efficiencies were 84%, 67% and 92%, respectively.

Process intensification of anaerobically digested palm oil mill effluent (AAD-POME) treatment using combined chitosan coagulation, hydrogen peroxide (H2O2) and Fenton’s oxidation

The present study investigates the removal efficiency of chemical oxygen demand (COD) and total suspended solids (TSS) of anaerobically digested palm oil mill effluent in batch studies through the following 4 strategies: coagulation by chitosan, addition of ferrous sulphate (FeSO4), chitosan with hydrogen peroxide (H2O2) and chitosan with Fenton oxidation. The parameters tested were chitosan dosage (500–12,500 mg/L), FeSO4 dosage (500–12,500 mg/L), mixing time (15–60 min), sedimentation time (1–4 h) and initial pH (2–9) and H2O2 (500–7500 mg/L). Coagulation only by using chitosan (2500 mg/L) achieved the maximum COD and TSS removal of 70.22 ± 0.23 and 85.59 ± 0.13 %, respectively. An increase in the TSS removal (98.7 ± 0.06 %) but with a reduction in the COD removal (62.61 ± 2.41 %) was observed when FeSO4 (2500 mg/L) was added along with chitosan (2500 mg/L). Alternatively, an improvement in the COD (82.82 ± 1.71 %) and TSS (89.92 ± 0.48 %) removal efficiencies was observed when chitosan was coupled with H2O2 (500 mg/L). Finally, chitosan (2500 mg/L) integrated with Fenton oxidation (FeSO4 of 2500 mg/L and H2O2 of 500 mg/L) resulted in 100 % TSS and 73.08 ± 4.11 % COD removals. Overall chitosan with H2O2 proved to be the most promising alternative for POME treatment compared to chitosan with Fenton oxidation. Industrial wastewater treatment exploiting advanced oxidation processes (AOPs) involves generation of hydroxyl radicals (OH ∙ ) to degrade the organic components and is a well-documented approach. In the present study, natural biomaterial chitosan as a coagulant combined with various AOP’s have been investigated for the anaerobically digested palm oil mill effluent (AAD-POME) treatment. Research investigations to-date on the post-treatment of POME is very limited, and the lacking of lab-scale study could be the major reason for the failing industrial plant trials. Hence the current study explores the possibility and reports in detail on an alternative eco-friendly green processing technique for POME treatment. The objectives of present investigation focuses on the post-treatment of AAD-POME primarily by coagulation using (a) chitosan (b) chitosan with FeSO4 (c) chitosan with H2O2 and (d) chitosan with Fenton oxidation. The results conclude that chitosan with H2O2 proved to be the most promising alternative for POME treatment compared to chitosan with Fenton oxidation.

The use of simulated rainfall to study the discharge process and the influence factors of urban surface runoff pollution loads.

An understanding of the characteristics of pollutants on impervious surfaces is essential to estimate pollution loads and to design methods to minimize the impacts of pollutants on the environment. In this study, simulated rainfall equipment was constructed to investigate the pollutant discharge process and the influence factors of urban surface runoff (USR). The results indicated that concentrations of total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) appeared to be higher in the early period and then decreased gradually with rainfall duration until finally stabilized. The capacity and particle size of surface dust, rainfall intensity and urban surface slopes affected runoff pollution loads to a variable extent. The loads of TP, TN and COD showed a positive relationship with the surface dust capacity, whereas the maximum TSS load appeared when the surface dust was 0.0317 g·cm⁻². Smaller particle sizes (<0.125 mm) of surface dust generated high TN, TP and COD loads. Increases in rainfall intensity and surface slope enhanced the pollution carrying capacity of runoff, leading to higher pollution loads. Knowledge of the influence factors could assist in the management of USR pollution loads.

Concentration of Total Suspended Solids (TSS) Influenced by the Simulated Rainfall Event on Highway Embankment

A model was constructed in compliance with the real conditions to study the behavior of total suspended solids (TSS) on the partially covered road side slopes. The study was performed in Perak, Malaysia where the average high rainfall intensity was found to be 52 mm/hr from the year 2005 to 2011. The results attained showed fluctuations in the TSS concentration observed from the partially covered soil surfaces that could have happened due to several reasons which are discussed in the paper. A sandy loam on a slope gradient of 30 ˚ was observed. Four plots were prepared namely, fully grass covered surface (plot A), bare soil surface (plot B), 50% of the grass covered surface (plot C), and 30% of the grass covered surface (plot D). The concentration of TSS was found to be very severe, attained from the bare soil surface (plot B). However, the maximum TSS values obtained from plot A, C, and D were found to be 22.29%, 45.62%, and 78.90% respectively of the maximum TSS value observed from the bare soil surface.

반응표면분석법을 이용한 터널폐수 응집-혼화 공정의 주요인자 영향 분석 및 최적화

A coagulation-flocculation (CF) process using aluminum sulfate as a coagulant was employed to treat highly suspended solids in tunnel wastewater. Response surface methodology (RSM) based on a Box-Behnken design was applied to evaluate the effects of three factors (coagulant dosage, pH and temperature) on total suspended solids (TSS) removal efficiency as well as to identify optimal values of those factors to maximize removal of TSS. Optimal conditions of coagulant dosage and pH for maximum TSS removal changed depending on the temperature (). As temperature increased, the amount of coagulant dosage and pH level decreased for maximum TSS removal efficiency during the CF process. Proper adjustment of optimal pH and coagulant dosage to accommodate temperature fluctuations can improve TSS removal performance of the CF process.

Response of Partially Covered Road Embankments and its Environmental Impact

Tropical regions have always suffered soil loss by water which deteriorates the surrounding environment in several ways. This paper focuses on one of an issue that under the tropical rainfall event how the newly constructed bare highway affects the water turbidity and total suspended solids in a water channel. The study was based on a pilot scale field test which was constructed in compliance with the real field conditions. The study was limited to the tropical rainfall event of 40 mm/hr, native grass cover, sandy loam, and for the road side slope of 1V:1.5H (~ 30°). To determine the turbidity and total suspended solids (TSS), three plots were observed with the different percentage of covers namely, no cover (plot A-control plot), 50% of the grass covered surface (plot B), and 30% of the grass covered surface (plot C). The purpose of the study was to observe the influence of these three plots on the dependent variables that is turbidity and TSS. The study summarizes that the presence of cover is adequate enough to cope with this issue to an extent. The results obtained showed that the bare soil surface performed worst under the rainfall intensity of 40 mm/hr for both the dependent variables. The maximum turbidity values observed from plot B and plot C were 30% and 90.25% respectively of the maximum turbidity value obtained from plot A. Similarly, the maximum TSS values observed from plot B and plot C were 35.21% and 63.76% respectively of the maximum TSS value observed from plot A.

Water Quality Effects of Herded Stream Crossings by Domestic Sheep Bands

Livestock impacts on total suspended solids (TSS) and pathogen (e.g., ) levels in rangeland streams are a serious concern worldwide. Herded stream crossings by domestic sheep () are periodic, necessary managerial events on high-elevation rangelands, but their impacts on stream water quality are largely unknown. We evaluated the effects of herded, one-way crossings by sheep bands (about 2000 individuals) on TSS and concentration and load responses in downstream waters. Crossing trials were conducted during the summers of 2005 and 2006 on two reaches within each of three perennial streams in the Centennial Mountains of eastern Idaho and southwestern Montana. Water samples were collected at 2-min intervals at an upstream background station and at stations 25, 100, 500, and 1500 m downstream just before and during each crossing trial. Crossings produced substantial increases in TSS and concentrations and loads downstream, but these concentration increases were localized and short lived. Maximum TSS concentration was highest 25 m downstream, declined as a function of downstream distance, and at 500 m downstream was similar to background. Post-peak TSS concentrations at all downstream stations decreased to <25 mg L within 24 to 48 min after reaching their maxima. Findings for concentration and load responses were similar to that of TSS but less clear cut. Stream-crossing sheep do affect water quality; therefore, producers and resource managers should continue to evaluate the efficacy of herdsmanship techniques for reducing water quality impact.

PREDICTING RIVER DIATOM REMOVAL AFTER SHEAR STRESS INDUCED BY ICE MELTING

ABSTRACTThe augmentation of fine particles and water velocity may have important effects on river biota, which have not been fully clarified. The aim of this study is to relate the removal of diatoms to changes in environmental variables during high‐stage flow in alpine streams.To achieve this goal, we adopted a path analysis approach. We hypothesized a causal model relating diatom presence to environmental predictors, and we tested it against data collected in two alpine rivers in NW Italy (Aosta Valley): Dora di Veny, directly fed by glaciers of the M. Bianco massif, and Savara, fed by springs. Total suspended solids (TSS) and velocity values were much higher in Dora di Veny, with a maximum velocity of 2.9 m s−1 and a maximum TSS of 2180 mg L−1. Absence of epilithic diatoms was recorded only three times in Savara, whereas it occurred in roughly half the samples in Dora di Veny. Diatom recolonization after natural removal generally occurred in early autumn, with a dominance of tightly attached forms. According to our path model, the explanatory variables causally related to the presence/absence of diatoms were water velocity, TSS and river feeding. The model estimated both direct and indirect effect weights of water velocity, thus discriminating the respective roles of shear stress (velocity) and abrasion of the substrates/increased turbidity (TSS, partly mediated by velocity).Our model allowed estimation of TSS and velocity threshold values and therefore inferences on the impact of physical alterations induced by natural or human causes. From a practical point of view, this may represent an applied outcome in the environmental impact assessment of engineering works and other human activities that could increase the TSS in rivers. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Remote sensing analysis of rainstorm effects on sediment concentrations in Apalachicola Bay, USA

Remote sensing of total suspended solids (TSS) by satellite techniques in estuaries and bays plays an important role in monitoring water quality over a large area. It is valuable to the management of coastal water environment and ecosystems. In this study, remote sensing mapping of TSS was conducted to investigate the effects of rainstorm events on Apalachicola Bay. A rainstorm event (October 7–8, 2008) was selected for a period when wind speeds were weak and the river inflow was almost steady. TSS mapping of MODIS images before and after the rainstorm event showed substantial increase of TSS induced by the rainstorm. Using an image during low river discharge before the rainstorm as a reference, TSS distribution was mapped by an improved regression model using MODIS image after a rainstorm event. Two thresholds of TSS (25 and 60 mg l − 1 ) were applied to delineate the rough edge of the sediment plume. The boundary separating highly turbid and relatively clear water was near Sikes Cut. The event did not influence the East Gulf Beach in the west side of East Pass. The study also shows the surface TSS concentrations can get back to their reference values (mean TSS at about 17 ~ 20 mg l − 1 and maximum TSS at about 70 mg l − 1 ) after 60 h and 50 min (i.e. almost the day 2.5) of rainstorm stopping. The method developed can be used to monitor sediment load to support estuarine ecological research and water quality assessment in Apalachicola Bay.

Efficiency of coconut coir-pith as an alternative substrate in the treatment of submerged macrophyte wetland systems in tropical conditions

The effects of coconut coir-pith as an alternative substrate material in submerged macrophyte wetland systems were investigated in three similar pilot-scale wetlands (WL1, WL2 and WL3) planted with Hydrilla verticillata. The substrate layers of WL1 and WL3 were river sand and coconut coir-pith, respectively, whereas that of WL2 was a mixture of river sand and coir-pith (ratio 1:1). The influent and effluent water-quality parameters were examined weekly to identify the effects of coir-pith on the treatment process. The results showed that the total nitrogen removal efficiency was higher in WL2 (52.3%) and WL3 (62.1%) than in WL1 (29.1%). The most efficient removals of biodegradable organic compounds (54.4%) and total dissolved solids (40.5%) were encountered in WL2, whereas the maximum total suspended solids (66.4%) and conductivity (38.5%) reductions were found in WL3. However, the PO–P removal efficiency was only slightly improved in WL2 (74.2%) and WL3 (74.4%) over WL1 (68.7%). Microbiological investigations revealed that WL2 and WL3 were more efficient in removing Escherichia coli than WL1. Statistical analyses by ANOVA showed that the water treatment efficiencies of WL2 and WL3 were substantially better than WL1 (p<0.05).

Biological treatment of anaerobically digested palm oil mill effluent (POME) using a Lab-Scale Sequencing Batch Reactor (SBR)

The production of highly polluting palm oil mill effluent (POME) has resulted in serious environmental hazards. While anaerobic digestion is widely accepted as an effective method for the treatment of POME, anaerobic treatment of POME alone has difficulty meeting discharge limits due to the high organic strength of POME. Hence, subsequent post-treatment following aerobic treatment is vital to meet the discharge limits. The objective of the present study is to investigate the aerobic treatment of anaerobically digested POME by using a sequencing batch reactor (SBR). The SBR performance was assessed by measuring Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) removal as well as Sludge Volume Index (SVI). The operating pH and dissolved oxygen concentrations were found to be 8.25–9.14 and 1.5–6.4 mg/L, respectively, throughout the experiment. The experimental results demonstrate that MLVSS, OLR and sludge loading rate (SLR) play a significant role in the organic removal efficiency of SBR systems and therefore, further investigation on these parameters was conducted to attain optimum SBR performance. Maximum COD (95–96%), BOD (97–98%) and TSS (98–99%) removal efficiencies were achieved at optimum OLR, SLR and MLVSS concentration ranges of 1.8–4.2 kg COD/m 3 day, 2.5–4.6 kg TSS/m 3 day and 22,000–25,000 mg/L, respectively. The effluent quality remained stable and complied with the discharge limit. At the same time, the sludge showed good settling properties with average SVI of 65. It is envisaged that the SBR process could complement the anaerobic treatment to produce final treated effluent which meets the discharge limit.

Notes. A survey of discharges from a natural gas-drilling operation in Lake Erie

We mapped turbid discharge plumes from a Canadian gas drilling rig by continuous-flow nephelometry and measured the concentrations of selected inorganic and organic constituents in the plumes. The buoyant surface plumes were from approx.600 to 1500 m long, with a maximum width of approx.250 m and areas less than 25 ha. Maximum total suspended solids in the discharge plumes were usuallly less than 5.0 mg/L and were rapidly dispersed when discharging ceased. Sodium, magnesium, sulfate, and chloride were diluted to ambient lake-water levels within 50 m of the drilling rig. Volatile hydrocarbons were <25 ..mu..g/L and dispersed quickly. Methane and ethane were enriched in the discharge plume but dispersed rapidly with increasing distance from the rig.