Total Volatile Suspended Solids Research Articles

Pilot-Scale Polyhydroxyalkanoate Production from Organic Waste: Process Characteristics at High pH and High Ammonium Concentration

Polyhydroxyalkanoate (PHA) accumulating microbial enrichment was established on volatile fatty acids (VFAs) containing leachate derived from the organic fraction of municipal solid waste (OFMSW). The enrichment was based on a 12-h feast-famine batch cycle and an exchange ratio of 50% in which VFAs were completely consumed in less than 50 min during stable periods of operation. No pH control was applied in the system, and the pH went as high as 9 due to the presence of amongst others, ammonia [500 mg·L−1 total ammonia nitrogen (TAN) on average]. The degree of enrichment was evaluated with fluorescence in situ hybridization (FISH), and a yet unknown genus of large (3–5 μm diameter) beta-proteobacteria appeared dominant in the culture. A method for estimating the fraction of PHA accumulating active biomass in the total volatile suspended solids was established, and the results indicated an increase of this fraction from 25% to 56% after implementing two modifications in the operational protocol: (1) a pretreatment of the substrate removing virtually all settleable solids; and (2) a settling phase in the enrichment reactor after the feast phase, selectively removing nonsettleable solids and slowly degradable substrates. The PHA accumulation potential of the culture was 77±18 wt% PHA (n=3) after 3 h in batch accumulation experiments. The results suggest the potential feasibility of PHA production under conditions that were previously considered economically favorable but technically difficult.

Denitrifying granules in a marine Upflow Anoxic Sludge Bed (UASB) reactor

Marine land-based Recirculating Aquaculture Systems (RAS) are generally perceived as environmentally friendly aquatic production systems. To promote their sustainability even further and reduce the discharge of nutrients, there is a need for cost-effective end-of-pipe treatment technologies for removing nutrients. This includes nitrate-nitrogen (NO3−-N) for which well-proven technologies for freshwater systems exists, while similar technologies for saltwater systems are less advanced. Granular technology has been developed since the 1970s in wastewater treatment under the upflow anaerobic sludge bed (UASB) concept. This concept is based on the enrichment of different bacterial aggregations into a compact granule, optimizing synergistic and syntrophic bacterial processes by reducing the diffusion distance of substrates between the different bacterial consortia forming the granule. The following study examined the: 1) granular formation; and 2) nitrate removal capacity of a marine Upflow Anoxic Sludge Bed (UASB) reactor operating at different up-flow velocities (0.40–2.11 m/h). The results showed that marine denitrifying granules developed within 27 days using preconditioned rainbow trout (Oncorhynchus mykiss) organic matter waste, and that the highest specific denitrification rate (321.9 ± 13.1 mg NO3−-N/g Total Volatile Suspended Solids (TVSS)/d) was found at an upflow velocity of 0.97 m/h. The marine UASB denitrifying granule reactor had a total capacity of removing 14.9 kg NO3−-N/m3 reactor volume per day at a hydraulic retention time of 1.9 h, making it a strong candidate for end-of-pipe denitrification of marine RAS effluent as well as for in-line treatment in marine systems.

Performance evaluation of a bottom liner incorporated up-flow anaerobic sludge blanket reactor start-up for food waste

A bottom biofilter liner incorporated up-flow anaerobic sludge blanket reactor was designed, developed, and evaluated for food wastes over 47 days. It was operated as a semi-batch setup with intermittent up-flow circulation (very infrequent) to simulate the start-up with phosphate, Ca(OH)2, and fresh cow dung. Volatile solids (VS), volatile suspended solids (VSS), salinity, pH, biochemical oxygen demand, chemical oxygen demand, and phosphate were monitored. An analytical procedure was developed by summing up total VSS over the lapse time from t = 0 for the operational period which gave overall reaction rate of v and the total cumulative values of VS as substrate S for applying Michaelis–Menten kinetics for optimizing and predicting reactor performance. At ideal operating conditions, pH ranged from 5.69 at the bottom to 7.9 at top stratum. The salinity at the bottom stratum reduced from 8.8 to 0.5 ‰, indicating excellent performance of the liner. There are two ways of analysing phase behaviour and applying Lineweaver Burk plot, one gave Michaelis–Menten kinetic parameters of vm=44.25 g/L/day and Km=76.02 g/L for 4th phase and vm=86.96 g/L/day and Km=66.26 g/L for 5th phase. Non-competitive inhibitions can be identified between these phases, thus best to arrest recirculation after 21 days and continuous feeding from then on.

Evaluating the Water Quality Benefits of a Bioswale in Brunswick County, North Carolina (NC), USA

Standard roadside vegetated swales often do not provide consistent pollutant removal. To increase infiltration and pollutant removal, bioswales are designed with an underlying soil media and an underdrain. However, there are little data on the ability of these stormwater control measures (SCMs) to reduce pollutant concentrations. A bioswale treating road runoff was monitored, with volume-proportional, composite stormwater runoff samples taken for the inlet, overflow, and underdrain outflow. Samples were tested for total suspended solids (TSS), total volatile suspended solids (VSS), enterococcus, E. coli, and turbidity. Underdrain flow was significantly cleaner than untreated road runoff for all monitored pollutants. As expected, the water quality of overflow was not significantly improved, since little to no interaction with soils occurred for this portion of the water balance. However, overflow bacteria concentrations were similar to those from the underdrain perhaps due to a first flush of bacteria which was treated by the soil media. For all sampling locations, enterococci concentrations were always higher than the USEPA geometric mean recommendation of 35 Most Probable Number (MPN)/100 mL, but there were events where the fecal coliform concentrations was below the USEPA’s 200 MPN/100 mL limit. A reduction in TSS concentration was seen for both overflow and underdrain flow, and only the underdrain effluent concentrations were below the North Carolina’s high quality water limit of 20 mg/L. Comparing results herein to standard swales, the bioswale has the potential to provide greater treatment and become a popular tool.

Microaerobic pretreatment of sewage sludge: Effect of air flow rate, pretreatment time and temperature on the aerobic process and methane generation

The effect of air flow rate (AFR), pretreatment time, and temperature on a microaerobic pretreatment were determined, including its effect on CH4 generation. For this, four AFR (0.1, 0.3, 0.5 and 1 vvm), three temperatures (20, 25 and 35 °C) and three aeration times (24, 48 and 60 h) were evaluated in 1-L and 5-L bioreactors. The effect on CH4 production was evaluated in 280-mL bioreactors, using previously aerated sewage sludge. It was found that the micro-aerobic pretreatment improves the hydrolytic process, with an increase of proteins, total sugars, soluble chemical oxygen demand (COD), and a greater removal of volatile suspended solids (VSS) compared to a system without aeration. It was determined that an AFR = 0.3 vvm, 48 h of aeration time, and a temperature of 35 °C were the best operational conditions for increasing hydrolysis rate. VSS removal under the aerobic pretreatment follows first order kinetics. Finally, the aeration pretreatment allows a 211% increase of methane generation compared to a process without pretreatment, improving also total COD and VSS removal.

Analysis of the built-up processes for volatile organics and heavy metals in suspended solids from road run-off

Road run-off water quality can be significantly impacted by many pollutants deposited on road surfaces through vehicular activities. Any control strategy for the improvement of water quality relating to organic and inorganic pollutants should be based on a detailed knowledge of pollutant built-up processes and the relationship of pollutants to one another. Total volatile suspended solids (VSS), polycyclic aromatic hydrocarbons (PAHs) and heavy metals were estimated in total suspended solids (TSS) collected in two catchments. This study found a good relationship between total VSS and TSS and between TSS and PAHs. This relationship information can be utilized for the development of effective Best Management Practices for TSS control. However, the relationship between TSS and heavy metals was identified as being strong in only some cases.

Optimization of Biological Elimination of Ammonia and Chemical Oxygen Demand from Wastewater Using Response Surface Methodology

Using a statistical technique, i.e. response surface methodology (RSM), optimization studies were carried out for different parameters like nitrogen ammonia (N‐NH3), chemical oxygen demand (COD) and time, to optimize overall method for maximum elimination of N‐NH3 and COD from synthetic waste water using heterotrophic biomass conversion (HBC) process, and simultaneously minimizing the N‐N2O emission. Ammonium hydroxide and glucose were used as nitrogen and carbon source. Central composite design technique was used to optimize the parameters with RSM. In this experiment, N‐NH3 and organic nutrient concentrations were varied keeping the biomass (total volatile suspended solids) concentration invariable. The pH during HBC process showed a decreasing trend may be due to consumption of alkalinity. Analyses of variance were carried out for quadratic model and were observed to be highly significant. The model was verified through experiments and tested statistically. Under optimized conditions (N‐NH3: 210 mg/L, COD: 2.90 g/L, time: 38 h) N‐NH3 and COD removal efficiency were observed to be 82.72 and 84.78%, respectively. N‐N2O emissions were minimized to 2.96 µg. The total desirability factor obtained was 0.9.

Optimization Study: Biological Removal of Inorganic Nitrogen along with Chemical Oxygen Demand from Wastewater Using Response Surface Methodology

A comparative optimization study using response surface methodology (RSM) was carried out for biological removal of various inorganic N–NH3 sources (NH4OH, (NH4)2SO4, NH4NO3) along with chemical oxygen demand (COD; glucose: C6H12O6) from synthetic wastewater and consequently minimizing the N–N2O emission. Heterotrophic biomass conversion (HBC) process was used for wastewater treatment. Central composite design (CCD) method was used to optimize various experimental parameters using RSM. During the experiment biomass (total volatile suspended solids) was kept constant, while varying nitrogen and carbon concentration, respectively. Alkalinity consumption results in pH decrease during the HBC process. N–NH3 and COD depletion rates were higher in NH4OH in comparison to the other two nitrogen sources. Analyses of variance observed highly significant differences. Models obtained through CCD method were checked and tested via experiments and statistics. Having optimum value, i.e., 210 mg/L N–NH3, 2.90 g/L COD and 38 h; higher COD (94.1%) and N–NH3 (82.72%) removal was observed in (NH4)2SO4 and NH4OH. Higher desirability factor was obtained in NH4OH.

NH3 and COD removal from wastewater using biological process: kinetic with optimization studies

Studies on heterotrophic biomass conversion (HBC) process were carried out for the removal of N–NH3 and organic carbon from wastewater. Ammonium sulfate and glucose were used as nitrogen and organic sources, respectively. A range of parameters were studied such as time, concentration variations of N–NH3, and organic nutrients keeping the biomass (total volatile suspended solids, TVSS) concentration invariable in all the cases. The kinetics followed dual rates, i.e. an initial faster phase, followed by the slower one. The rates of N–NH3 and chemical oxygen demand (COD) removal depended on their initial concentrations. The consumption of N–NH3 and COD followed first order kinetics. The unified rate equation was also established. Two other kinetic models, such as Monod and diffusion, were studied. The pH during the HBC process showed a decreasing trend. Other parameters studied were: N–NO3-, N2O, N–NO2-, and DO. A part of N–NH3 utilized for emission of N2O may be due to heterotrophic nitrification (HN). Statistical studies were carried out such as analyses of variance (ANOVA), multi linear regression analysis and principal component analysis (MLRA), and pricipal component analsis (PCA). Optimization studies were carried out using response surface modeling (RSM) to maximize the removal efficiency of N–NH3 and COD, minimizing the N–N2O emissions, along with maximizing the TVSS production simultaneously.

Preliminary study on filamentous particle distribution in septic tank effluent and their impact on filter cake development

In this paper, the preliminary study on the impact of filamentous particles (FP) in the septic tank effluent (STE) on filter cake (FC) development was presented. The number, length and diameter (30 p./cm3, 451 and 121 μm, respectively, on average) of FPs were measured using microscope image analysis of STE samples condensed using a vacuum evaporation set. Results of this study showed, that 0.73% of volatile suspended solids (VSSs) mass from the STE occurs in the form of FPs. No correlation between FP total mass and VSS was found. An experiment with a layer of FPs simulated by ground toilet paper was conducted and showed the impact of this layer (4.89 mg/cm2) on wastewater hydraulic conductivity – for an FC with FPs (FC–FP), hydraulic conductivity was seven times lower than for the FC without the FP layer, and on outflow quality (lower concentration of organic matter expressed as chemical oxygen demand (COD) in effluent from the FC–FP filter than in the effluent from the FC filter: 618 and 732 gO2/m3, respectively). Despite a relatively small amount of FPs in STE solids (as volume fraction), they play an important role in FC development due to their relatively high length and low degradability. Probably relatively small pores of the FC containing FPs (FC–FP) caused a small particle blocking and a decrease in permeability.

Determination of Chemical Oxygen Demand in Substrates from Anaerobic Treatment of Solid Organic Waste

A modified method is described for the determination of the chemical oxygen demand (COD) of samples with high solids content, especially those used in biogas production. The modified method is based on ISO 6060 and DIN 38414 methods. Analyses with potassium hydrogen phthalate solution standard showed that the modified method is valid and gives equal results to standard method (9,960 mg/L determined by ISO method, and 9,930 mg/L by modified methods). Comparison of the standard method with the new proposed method using actual samples shows that the modified method gives more reliable results than the standard method. The standard ISO 6060 method is more appropriate for samples with homogeneous solids, where uniform dilution is easy to achieve. Although the modified method shows slightly more accurate results, the increased chemical expense associated with the modified method does not justify its use. The proposed modified method is especially appropriate for wet solid samples with high total volatile suspended solids content and the COD values of up to 400,000 mg/kg. COD for waste activated sludge determined by ISO 6060 method was 47,300 and 52,800 mg/kg determined by modified method. COD of original wet solid sample was 360,000 mg/kg, and COD for previously dried samples at 105°C was 345,000 mg/kg. For anaerobically digested sludge the COD was 80,800 mg/kg, and COD for previously dried samples at 105°C was 72,700 mg/kg. The difference is attributed to the loss of volatile compounds in drying. Applying the modified method, samples need no preparation and are analysed in their basic wet form as they are collected from anaerobic digesters. Analysis has shown that currently available methods for COD determination with samples containing high amounts of solids require drying of the sample with the loss of volatile components. This may lead to inaccurate results.

Treating swine wastewater by integrating earthworms into constructed wetlands

The aim of this study was to investigate the application of integrating earthworms (Pheretima peguana) into two-stage pilot-scale subsurface-flow constructed wetlands (SFCWs) receiving swine wastewater in terms of their treatment performance, namely organic content, total kjeldahl nitrogen (TKN), and solid reduction as well as the quantity of sludge production. There was a minor difference in terms of removal efficiency according to each parameter when comparing the unit with earthworms to the one without earthworms. Both achieved the TKN, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total volatile suspended solids (TVSS), suspended solids (SS), and total solids (TS) removal by more than 90 %. The earthworms helped in reducing the sludge production on the surface of constructed wetlands 40 % by volume, which resulted in lowering operational costs required to empty and treat the sludge. The plant biomass production was higher in the wetlands without earthworms. Further research could be undertaken in order to effectively apply earthworms inside the wetlands.

Potential Effluent Quality from Commercial Crawfish Ponds

AbstractSeventeen commercial and two demonstration crawfish ponds in southern Louisiana that were either planted with rice Oryza sativa or a sorghum‐sudangrass hybrid (Sorghum bicolor × S. sudanese) or colonized with volunteer terrestrial or semiaquatic vegetation were evaluated for potential effluent quality. Nutrients and solids concentrations in potential crawfish pond effluents increased significantly in spring and summer from fall and winter levels. Potential effluent quality was poorest during the annual summer drawdown and is likely to have the greatest impact on receiving waterways. Total suspended solids and turbidity most frequently exceeded Louisiana water quality standards. Ponds with volunteer vegetation had significantly lower concentrations of chemical oxygen demand, turbidity, total suspended solids, total volatile suspended solids, and total Kjeldahl nitrogen than ponds with rice and sorghum‐sudangrass. Soluble reactive phosphorus, total phosphorus, total ammonia, nitrite, and nitrate were highest in ponds with sorghum‐sudangrass. Nutrient and solid concentrations were generally lower in ponds with volunteer vegetation, presumably as a result of nutrient uptake by aquatic macrophytes and reduced suspended sediment loads. Establishing limited stands of aquatic macrophytes inside crawfish ponds or using effluent to replenish water in adjacent ricefields may reduce the amount of suspended solids and nutrients entering receiving waters.

A Laboratory Scale Sequencing Batch Reactor with the Addition of Acetate to remove Nutrient and Organic Matter in Pig Slurry

The influence of carbon addition on performance of a laboratory-scale, anaerobic–anoxic–anaerobic–anoxic sequencing batch reactor [(An/Ax)2 SBR] in biologically removing nitrogen and organic matter from swine slurry was investigated in this study. The SBR was operated on three cycles per day (8 h per cycle) at constant 20 °C using raw slurry feeding until it reached a steady functional condition. After that, the SBR was subjected to a feeding treatment with addition of acetate. The sludge retention time and hydraulic retention time were maintained at 21 and 3·3 days for the experiment. The results indicate that with acetate addition, the removals of ammonium nitrogen, total Kjeldahl nitrogen, chemical oxygen demand, biochemical oxygen demand, and total phosphorus are 100·0%, 98·7%, 97·4%, 100·0%, and 98·7%, respectively. While without acetate addition, the corresponding reductions are 100·0%, 100·0%, 97·7%, 100·0%, and 97·8%. None of the feeding treatments (slurry alone or with acetate) appear to be effective in removing nitrate and nitrite due possibly to insufficient time allocated for denitrification, even when carbon is readily available. The removal of dissolved phosphorus by phosphorus-accumulating organisms reaches 87·2% with acetate addition but only 67·9% without. A good reduction in total solids (77·5% and 78·8%), total volatile solids (97·0% and 95·6%), total suspended solids (99·9% and 99·3%), and total volatile suspended solids (99·1% and 98·4%) for both treatments is also observed.

Effects of Duration and Intensity of Aeration on Solids Decomposition in Pig Slurry for Odour Control

A 30 day laboratory scale experiment was carried out using three different aeration rates, i.e. +35 mV oxidation–reduction potential (ORP: standard hydrogen electrode), 1·0, and 3·0 mg[O 2 ] l −1 , to achieve solids decomposition and odour control in pig slurry with total solids (TS) levels from 0·5 to 4·0%. Changes during the aeration process were characterised by TS, total volatile solids (TVS), total suspended solids (TSS), and total volatile suspended solids (TVSS), all expressed as w/w. The measurement of volatile fatty acids (VFAs), expressed as w/v, was used to evaluate the potential odour generation in the aerated slurry. The TS removal efficiencies from 6·0 to 44·9, 18·6 to 50·3, and 42·3 to 56·4% were observed for the three different aeration levels, with reductions from 6·6 to 48·9, 26·0 to 61·1, and 57·3 to 69·9% for the slurry TVS. The ratios of TVS/TS, TSS/TS, and TVSS/TS in slurry over the experimental duration were found to increase with increased TS levels in the 30 day aeration under the three aeration intensities. Reductions in the 5 day biological oxygen demand (BOD 5 ) reached 78·5–92·0, 79·4–96·0, and 91·2–97·0%, while reductions of VFAs reached 12·7–99·0, 71·7–99·0%, and 87·8–99·3%. The biodegradation of solids, BOD 5 , and VFAs was effectively enhanced when aeration time and intensity were increased. A low level of solids in slurry promoted aerobic decompositions of solids, BOD 5 , and VFAs. Changes of state in the solids being aerated and changes in the BOD 5 levels can be used to distinctly characterise the potential of odour generation from the slurry. Batch aeration of 5–10 days under intensities of 1·0 to 3·0 mg[O 2 ] l −1 is recommended for odour control at farm level.

Viability of Anaerobic Digester Sludge

The viability of biological sludges is commonly expressed as the active bacterial concentration per unit mass volatile suspended solids (VSS). Due to the high concentration of paniculate matter in anaerobic sludge digester feed, digester volatile solids contain a large concentration of nonbacterial mass. Viability of anaerobic sludge based on sludge digester total VSS will therefore underestimate the active mass. Based on adenosine triphosphate (ATP) measurements, only 5 to 10% of the total VSS represents active bacterial biomass. Bacterial viability based on the biomass VSS fraction in the anaerobic sludge digester is much higher than viabilities based on total VSS. Using a kinetic model of anaerobic sludge digestion, the biomass VSS can be estimated. For sludge ages exceeding 10 days, less than 20% of the total volatile solids represents biomass—the remainder consists of biodegradable VSS not yet hydrolyzed for bacterial uptake and inert VSS. This means that 40 to 50% of the biomass VSS in anaerobic slu...

Aerobic sludge digestion at cold temperatures

Continuous flow, daily fill and draw, and batch aeration digesters were studied on a laboratory scale, to develop low temperature characteristics and design criteria for aerobic digestion of waste-activated sludge. These results were compared against full-scale data, from three independent sources. Raw sludge used in these studies was obtained from a municipal high-rate activated sludge plant. The digestion systems were operated at temperatures of 20, 10, and 5 °C, and at six different sludge ages. Measurements of all parameters studied were made under steady-state conditions.The results show that the effect of low temperature on aerobic digester performance is pronounced. The combined effect of temperature and sludge age is shown to be an important design parameter. Kinetic reaction rates and temperature coefficients were calculated on the basis of total volatile suspended solids. It was shown that batch and continuous feed system reaction rates are not interchangeable. The laboratory results further show that there is little difference between continuous flow and daily fill and draw digestion characteristics, except at 5 °C. Difficulties encountered in making a valid comparison between the laboratory and full-scale results are also discussed.