Biomass accumulation and carbon utilization in layered sand filter biofilm systems receiving milk fat and detergent mixtures

This research evaluated utilization of organic compounds and biomass accumulation in three different layered sand filter biofilm systems renovating a mixture of detergent and milk fat. Organic compounds were measured as chemical oxygen demand (COD) and biomass as ATP. A two-layer sand filter with coarse sand on the top and fine sand at the bottom; a three-layer sand filter with pea gravel on the top, coarse sand in the middle, and fine sand at the bottom; and a two-filters in-series sand filter biofilm system each received mixtures of butterfat and detergent. While the three-layer sand filter system had greater COD utilization capacity due to a longer filter run, the two-filters in-series sand filter system had greater COD utilization efficiency. The COD utilization was highly associated with the period of filter run to clogging. The decrease of COD utilization rate could lead to the clogging of sand filters. To maintain long filter runs without clogging, a COD loading rate of 2100 mg O(2)/m(2)/h was recommended for three-layer sand filters and 1800 mg O(2)/m(2)/h for two-layer sand filters for high fat content wastewater. In the two-layer sand filters and the three-layer sand filters, biomass did not seem to accumulate in any particular layer on a unit volume of sand. However, based on unit surface area, the coarse sand layer accumulated more biomass than the fine sand layer and the pea gravel layer.     

Treatment of turkey processing wastewater with sand filtration

This research investigated the feasibility of coarse/fine sand filtration for removing organic materials from turkey processing wastewater. Sand filtration was tested with three organic and hydraulic loadings. Six two-layer sand bioreactors were in three groups, each with 5 cm layer of pea gravel at the bottom to support layers of fine sand (46 cm) and coarse sand (15 cm) to a height of 66 cm. The bioreactors were inoculated with a mixture of 20% (vol/vol) of wastewater lagoon sludge, 40% (vol/vol) of turkey processing wastewater, and 40% (vol/vol) of BOD(5) dilution water before starting the column operation with turkey processing wastewater. The wastewater contained 1270+/-730 mg COD/L and was applied to each sand bioreactor at hydraulic loading rates of 94% during 80 days of column operation at low and medium hydraulic loading rates (132 L/m(2)/day). The removal at the highest hydraulic loading rate (264 L/m(2)/day) declined after the appearance of a black zone in the top layer of fine sand on day 30 for one reactor and day 50 for the other. The sand filtration in this study represents a feasible treatment for turkey processing wastewater and its efficiency and the life span of the process are associated with the extent of hydraulic loading of the sand bioreactors.     

Bioremediation of Vegetable Oil and Grease from Polluted Wastewater Using a Sand Biofilm System

Pseudomonas sp. (L1), P. diminuta(L2) were among eight bacterial strains isolated from vegetable grease and oil-contaminated industrial wastewater, four of which only were found to have the ability to degrade oil and grease. They were identified and investigated for oil and grease degradation either individually or in combinations in previous unpublished work by the authors. Since the combination M1 (Pseudomonas sp. andP. diminuta) produced the highest degradative activity, it was used in the present study in a biofilm sand filter system for vegetable oil and grease removal. This system was tested either as one unit or two units in sequence where different flow rates (30, 50, 100 ml/h) were applied compared to a control unit(s). Results showed that both biofilm systems reduced oily wastewater, even in cases of high degree of pollution (fat, oil & grease (FOG), 7535 ppm; biochemical oxygen demand (BOD₅), 525 ppm; chemical oxygen demand (COD), 1660 ppm). Results also showed a removal of FOG with efficiency at 100%; BOD₅ at 95.9% and COD at 96%, at 50 ml/h flow rate using one unit of biofilm system. On using two units in sequence, a complete removal of FOG, BOD₅ and COD with efficiency 100%, at flow rate 100 ml/h was achieved. In conclusion, the previous biofilm results indicated the efficiency of such a system in treating oily polluted wastewater (vegetable oil origin) on the basis of bacterial isolates being used, the optimum flow rate, and the number of biofilm units used in sequence to obtain the highest removal capacity of such a system. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dyestuff wastewater treatment using chemical oxidation,physical adsorption and fixed bed biofilm process

Fenton’s oxidation and activated carbon adsorption were examined as pretreatment processes for dyestuff wastewater having high salinity, colour, and non-biodegradable organic concentrations. In this work, each wastewater stream produced by individual production processes was classified as streams R1, R2, and R3. The stream having a value of BOD₅/COD lower than 0.4 was pretreated by Fenton’s oxidation or activated carbon adsorption to increase the ratio of BOD₅/COD which indicates biodegradability. For Fenton’s oxidation with one stream having a value of BOD₅/COD lower than 0.4, the optimal reaction pH was 3.0 and the minimum dosing concentration (mg l⁻¹) of H₂O₂:FeSO₄·7H₂O was 700:3500. Stream R3, which consisted mainly of methanol was efficiently treated by activated carbon adsorption. The ratio of BOD₅/COD was also increased to 0.432 and 0.31 from 0.06 in Fenton’s oxidation and activated carbon adsorption, respectively. A biological treatment system using a fixed bed reactor was also investigated to enhance biological treatment efficiency at various hydraulic retention times, pretreatment conditions by Fenton’s reagent and salt concentrations by dyestuff wastewater. In addition, the efficiency of Fenton’s oxidation as a post-treatment system was also investigated to present a total treatment process of dyestuff wastewater. As the influent COD and salinity were increased, the effluent SS and COD were consequently increased. However, as the microorganisms became adapted to the changed influent condition, the treatment efficiency of the fixed bed reactor quickly recovered under the high COD and salinity since the microorganisms were well adapted to toxic influent conditions. A wastewater treatment process consisting of chemical oxidation, activated carbon adsorption, fixed bed biofilm process and Fenton’s oxidation as a post-treatment system can be useful to treat dyestuff wastewater having high salinity, colour, and non-biodegradable organic concentration.     

Biodegradation of olive-mill pomace mixed with organic fraction of municipal solid waste

This study investigated the effects of organic fraction of municipal solid waste (OFMSW) addition on the anaerobic treatment of the olive-mill pomace. Biodegradability of olive-mill pomace mixed with OFMSW was examined in anaerobic bioreactors. Only OFMSW was loaded in the first (control) bioreactor, while run 1 and run 2 bioreactors included different ratio of OFMSW and olive-mill pomace. COD, BOD₅, NH₄–N, pH, VFA, CH₄ quantity and percentage in anaerobic bioreactors were regularly monitored. In addition, inert COD and anaerobic toxicity assay (ATA) were measured in leachate samples. The results of the study showed that 70% of OFMSW addition to olive-mill pomace has an advantage in terms of pollution parameters and methane generation. Since olive-mill pomace is not easy biodegradable, addition of high proportion of OFMSW promotes biodegradability of olive-mill pomace. Decreasing in BOD₅/COD ratios in the run 1 and run 2 reactors carried out as 62 and 52%, respectively.     

Partial nitrification and nutrient removal in intermittently aerated sequencing batch reactors treating separated digestate liquid after anaerobic digestion of pig manure

The performance of an intermittently aerated sequencing batch reactor (IASBR) technology was investigated in achieving partial nitrification, organic matter removal and nitrogen removal from separated digestate liquid after anaerobic digestion of pig manure. The wastewater had chemical oxygen demand (COD) concentrations of 11,540 ± 860 mg/L, 5-day biochemical oxygen demand (BOD₅) concentrations of 2,900 ± 200 mg/L and total nitrogen (TN) concentrations of 4,041 ± 59 mg/L, with low COD:N ratios (2.9) and BOD₅:COD ratios (0.25). Synthetic wastewater, simulating the separated digestate liquid with similar COD and nitrogen concentrations but BOD₅ of 11,500 ± 100 mg/L, was also treated using the IASBR technology. At a mean organic loading rate of 1.15 kg COD/(m³ d) and a nitrogen loading rate of 0.38 kg N/(m³ d), the COD removal efficiency was 89.8% in the IASBR (IASBR-1) treating digestate liquid and 99% in the IASBR (IASBR-2) treating synthetic wastewater. The IASBR-1 effluent COD was mainly due to inert organic matter and can be further reduced to less than 40 mg/L through coagulation. The partial nitrification efficiency of 71–79% was achieved in the two IASBRs and one cause for the stable long-term partial nitrification was the intermittent aeration strategy. Nitrogen removal efficiencies were 76.5 and 97% in IASBR-1 and IASBR-2, respectively. The high nitrogen removal efficiencies show that the IASBR technology is a promising technology for nitrogen removal from low COD:N ratio wastewaters. The nitrogen balance analysis shows that 59.4 and 74.3% of nitrogen removed was via heterotrophic denitrification in the non-aeration periods in IASBR-1 and IASBR-2, respectively.     

Mountain cheese factory wastewater treatment with the use of a hybrid constructed wetland

This paper describes the activity period of an experimental hybrid wetland system placed in a cold climate region. The aim is to determine the efficiency of the system in reducing TSS, BOD₅, COD and other pollutants. The constructed wetland consists of a fat-removal unit and a basin for the storage and the distribution of the wastewater which precedes three phytoremediation beds: the first two are parallel and they work as submerged vertical flow wetland with gravel medium for an area of 180 m²; the last is a submerged horizontal flow wetland with sand medium and an area of 360 m². The CW was designed to process a total estimated BOD₅ loading rate of about 24 g m⁻² d⁻¹, which was less than half of the average actual loading rate. The wastewater treatment did not meet the required Italian law outflow limits, most likely due to BOD₅ overloading.     

Generating “Tide” in Pilot‐Scale Constructed Wetlands to Enhance Agricultural Wastewater Treatment

The operation of tidal flow was studied using a pilot‐scale system treating high strength piggery wastewater. Located on a farm in Staffordshire, UK, the system consisted of five wetland treatment stages vegetated with common reeds of Phragmites australis. Wastewater samples were collected from the inlet and outlet of each stage and analyzed for BOD₅, COD, NH₄‐N, NO₃‐N, NO₂‐N, SS, PO₄‐P and pH. Average hydraulic and organic loadings on the system were 0.12 m³/m² d and 240 g BOD/m² d, respectively, which is considerably higher than the typical loadings on conventional subsurface flow systems. On average, BOD₅ and COD were reduced by 82 % and 80 % from initial concentrations of 2000 mg/L and 2750 mg/L, respectively, across the whole system. The first‐order kinetics constant for BOD₅ removal (K_BOD in m/d) in this tidal flow system is approximately 2.5 times the rate constant obtainable in a typical horizontal flow system, demonstrating a more efficient removal of organic matter in tidal flow wetlands. The overall efficiency of the system was found to increase with time before stabilizing towards the end of a start‐up period. Straight‐line correlations were established between the loading and removal of BOD₅ and COD. Contributions by individual stages to the overall treatment were analyzed. SEM images of wetland media demonstrated the formation of biofilms and microbial activities inside the matrices of the wetland system, which accounted for the degradations of organic pollutants.     

Improving wastewater effluent filtration by changing flow regimes—Investigations in two cold climate pilot scale systems

Two pilot-scale experimental filter systems (FSs) filled with light-weight aggregates (LWA) or crushed limestone (CL) and operated under different flow regimes were established during the summer of 2005. The main objective of the study was to compare continuous-flow hybrid CL and LWA filters and batch-operated LWA filters in order to determine optimal loading, design parameters, management schemes and operational regimes for LWA-based FSs in cold climate conditions for the secondary treatment of domestic wastewater. With higher re-circulation rates of treated water, purification efficiency increased in terms of most water quality indicators in both types of filter systems. In the batch-operated FS the highest purification efficiencies of 96% and 51% for BOD₇ and N_tot, respectively, were achieved when the re-circulation rate of 200% was applied. In the continuous-flow FS the highest purification efficiencies of 99% and 81% for BOD₇ and N_tot, respectively, were achieved when the re-circulation rate up to 300% was applied. In order to achieve effective organic matter removal, nitrification/denitrification and TSS removal, the re-circulation rate must be from 100% to 300% of the inflowing wastewater. Both FS designs, the continuous-flow hybrid systems and the batch-operated filters, are suitable for the secondary treatment of domestic wastewater in cold climate conditions.     

Constructed wetlands for the treatment of landfill leachates: The Slovenian experience

Constructed wetlands are widely recognized as an economical, efficient and environmentally acceptable means to treat many different types of wastewater. Six systems have been constructed in Slovenia for the treatment of landfill leachates. This paper describes the early stages of two treatment systems operating from 1990 to 1993 that were used to treat leachates from municipal landfills. System S1 consisted of a sedimentation lagoon and a 600 m² reed bed. System S2 was designed with a sedimentation lagoon and two reed beds (total=450 m²). The subsurface flow in both was horizontal and fluctuated widely in S2, but was a constant 0.2 1 s^–1 in S1. Peat, soil, sand and gravel were in system S2, while gravel with a hydraulic conductivity of 5×10^–4 m s^–1, was in S1.The unanticipated fluctuations of hydraulic and organic loadings influenced their performance. The efficiency in reduction of organic matter, N, P, metals and fecal coliforms varied through the year. In 3 years of operation, the average removal efficiencies for COD, BOD₅ and TSS were 38%, 61%, and 81%, respectively, in S1, and 53%, 45%, and 47%, respectively, in 1.5 years of operation for S2. The reduction of ammonium did not reach the effluent standard of 10 mg l^–1 for either S1 or S2. As, Zn, Pb, and Cu accumulated in roots, and Cu, Fe, As, Ni and Pb accumulated in rhizomes after one year of operation in S2.     

Performance of an anaerobic baffled reactor and hybrid constructed wetland treating high-strength wastewater in Nepal—A model for DEWATS

Centralized wastewater treatment systems require sophisticated technologies and skilled manpower for their operation and maintenance (O&M). These systems have huge construction as well as O&M costs. Therefore, a Decentralized Wastewater Treatment System (DEWATS) rather than a centralized system might be especially beneficial in developing countries. A model for DEWATS is developed in Nepal with Anaerobic Baffled Reactor (ABR) and hybrid Constructed Wetland (CW). The DEWATS treats high-strength wastewater from 80 households (400 PE). This paper summarizes the performance of the DEWATS from July 2006 to August 2007 in the removal efficiencies of TSS, BOD₅, COD, NH₄–N, TP and FC. The ABR is very effective in the removal of organic pollutants and could achieve TSS removal up to 91%, BOD₅ up to 78% and COD up to 77%. The average removal efficiencies of the DEWATS is 96% TSS, 90% BOD₅, 90% COD, 70% NH₄–N, 26% TP and 98% FC.     

Treatment of landfill leachate using UASB-MBR-SHARON–Anammox configuration

Leachate treatment is a challenging issue due to its high pollutant loads. There are several studies on feasible treatment methods of leachate. In the scope of this study, high organic content of young leachate was eliminated using an upflow anaerobic sludge blanket (UASB) and a membrane bioreactor (MBR) in sequence and effluent of the system was given to single reactor for high activity ammonia removal over nitrite (SHARON) and anaerobic ammonia oxidation (Anammox) reactors to remove nitrogen content. All reactors were set up at lab scale in order to evaluate the usage of these processes in sequencing order for leachate treatment. COD and TKN removal efficiencies were over 90 % in the combined processes which were operated during the study. The biodegradable portion of organic matter was removed with an efficiency of 99 %. BOD₅ concentration decreased to 50 mg/L by UASB and MBR in sequence even the influent BOD₅ concentration was over 8,000 mg/L. Although high nitrogen concentrations were observed in raw leachate, successful removal of nitrogen was accomplished by consecutive operations of SHARON and Anammox reactors. The results of this study demonstrated that with an efficient pretreatment of leachate, the combination of SHARON–Anammox processes is an effective method for the treatment of high nitrogen content in leachate.     

Evaluation of the treatment performance of lab-scaled vertical flow constructed wetlands in removal of organic compounds,color and nutrients in azo dye-containing wastewater

The objective of this study is to examine the treatment performance of vertical flow intermittent feeding constructed wetland (VFCW) in removal of organic pollution, nutrients and color in azo-dye containing wastewater. The systems consisted of PVC reactors, some filling materials such as gravel, sand and zeolite and wetland plants including Typha angustifolia and Canna indica. The average treatment efficiency of the systems for COD, color, sulphate, NH₄-N, and PO₄-P were in the range of 57–63%, 94–99%, 44–48%, 39–44%, and 84–88%, respectively among the VFCW reactors. It is concluded that VFCW reactor system can effectively be used in the treatment of dye-rich wastewater, especially for the removal of color and in the reduction of COD. Biofilm formation and cleavage of azo bonds could be observed by SEM and FTIR results, respectively. Almost similar NH₄-N and PO₄-P removal were obtained in all reactors by using same amount of zeolite media.     

Feasibility study of a cyclic anoxic/aerobic two-stage MBR for treating ABS resin manufacturing wastewater

This study investigated the feasibility and the treatment efficiency of a cyclic anoxic/aerobic two-stage MBR for treating polymeric industrial wastewater. The anoxic/aerobic hybrid MBR was operated without sludge withdrawal except sampling during the study. The results showed that the highest COD organic loading rate of 8.7 kg COD/m³ day from bioreactor was obtained at phase 3. The system achieved 97% BOD₅ and 89% COD removal. It also revealed that 93% of COD removal was contributed by bioreactor at phase 3 and the similar results happened to phases 1 and 2. The highest TN and TKN removals for each phase were 60, 74, 80% and 61, 74, 81%, respectively and limited by nitritation step. SEM images of nascent and fouled membranes were offered to evaluate the cleaning method. The system was operated for 174 days, resulting in high degradation rate, flexibility towards influent fluctuations and limited sludge production.     

Evaluation of an on-site pilot static granular bed reactor (SGBR) for the treatment of slaughterhouse wastewater

An on-site pilot-scale static granular bed reactor (SGBR) system was evaluated for treating wastewater from a slaughterhouse in Iowa. The study evaluated SGBR reactor suitability for slaughterhose wastewater having high particulate COD concentration (7.9 ± 4.3 g COD/L) at 0.3–1.4 m³/m²/day of the surface loading rates. High organic removal efficiency (over 95% of TSS and VSS removal) was obtained due to the consistent treatability of SGBR system during operation at HRTs of 48, 36, 30, 24, and 20 h. The average effluent TSS, VSS, COD, soluble COD, and BOD₅ concentrations were 84, 71, 301,197, and 87 mg/L, respectively. An effective backwash procedure was performed once every 7–14 days to waste a portion of the accumulated solids in the system. This procedure limited the increase in hydraulic head loss and maintained the system stability. COD removal efficiencies greater than 95% were achieved at organic loading rates ranging from 0.77 to 12.76 kg/m³/day.     

Polishing low-biodegradable and saline industrial effluent in a full-scale horizontal subsurface flow constructed wetland: evaluation of bio-treatability and predictive power of kinetic models

Abstract

This study evaluates the bio-treatability performance and kinetic models of full-scale horizontal subsurface flow constructed wetland used for the tertiary treatment of composite industrial effluent characterized by high-salt content ranging from 5830 to 10,400 µS/cm and biochemical oxygen demand (BOD₅): chemical oxygen demand (COD) ratio below 0.2. The wetland vegetated with Phragmites australis was operated in a semi-arid climate under an average hydraulic loading rate of 63?mm/d. The results of a 4-year operation calculated based on the concentration of pollutants showed that the average removal efficiency of COD, BOD_5, and total suspended solids (TSS) were 17.5, 5.1, and 11.2%, respectively. The system reduced up to 6.5?±?0.7% of electrical conductivity presenting poor phyto-desalination potential without considering the contribution of evapotranspiration in water balance in contrast to satisfying performance for heavy metals reduction. The comparison of the kinetics of organic matter removal obtained by the first-order and Monod models paired with continuous stirred-tank reactor and plug flow regime showed that Monod-plug flow model provided the best fit with the constants of 2.01?g COD/m²·d and 0.3014?g BOD₅/m²·d with the best correlation coefficient of 0.610 and 0.968 between the predicted and measured concentrations, respectively. The low kinetic rates indicate that the process is capable of effluent polishing instead of purification due to the presence of organic compounds recalcitrant to biodegradation and a high level of salinity.     

不同母岩发育土壤的可氧化态有机碳

采用KMnO4氧化法测定了8种不同母岩发育形成的土壤的可氧化态有机碳含量,结果表明,发育母岩不同,土壤可氧化态有机碳含量显著不同。通过对土壤养分、土壤颗粒组成、容重与可氧化态有机碳含量的相关性分析表明,土壤可氧化态有机碳与土壤的速效磷、全氮、速效钾、砂粒、粉粒的含量存在着极显著负相关关系;与土壤容重存在着极显著的正相关关系;与土壤的有机质、碱解氮、粗砂、细砂、粘粒、pH值、石砾含量无相关关系。     

Macrophyte beds contribute disproportionately to benthic invertebrate abundance and biomass in a sand plains stream

Macrophyte beds have been shown to influence organic matter retention and nutrient processing in streams. Less is known about the extent to which plant beds contribute to abundance, biomass, and diversity of macroinvertebrate assemblages in low-order streams. We measured aquatic invertebrate abundance, biomass, and diversity associated with plant beds and sand/gravel patches in a low-gradient second-order stream in the Central Sand Plains of Wisconsin, USA from March to October. Invertebrate abundance and biomass were higher on average in plant beds (2,552 m⁻² and 1,575 mg m⁻²) than in sand/gravel patches (893 m⁻² and 486 mg m⁻²). Although sand/gravel habitat was over three times more abundant than plant beds in the study reach, plant beds and sand/gravel patches contributed similarly to invertebrate abundance and biomass at the whole-reach scale. The abundance and biomass of invertebrates associated with plant beds decreased from spring to autumn. Non-insect invertebrates in the plant beds increased in relative abundance as the year progressed. Shannon–Weiner diversity and taxa richness of invertebrates were higher in the plant beds than in the sand/gravel habitat. Our results suggest that plant beds can represent hot spots for invertebrate abundance and production in low-gradient streams, and have implications for stream management and restoration in these types of ecosystems. Handling editor: S. I. Dodson     

Coupling of anodic biooxidation and cathodic bioelectro-Fenton for enhanced swine wastewater treatment

A novel bioelectrochemical reactor with anodic biooxidation coupled to cathodic bioelectro-Fenton was developed for the enhanced treatment of highly concentrated organic wastewater. Using swine wastewater as a model, the anode-cathode coupled system was demonstrated to be both efficient and energy-saving. Without any external energy supply to the system, BOD₅, COD, NH₃-N and TOC in the wastewater could be greatly reduced at both 1.1 g COD L⁻¹ d⁻¹ and 4.6 g COD L⁻¹ d⁻¹ of OLR, with the overall removal rates ranging from 62.2% to 95.7%. Simultaneously, electricity was generated at around 3-8 W m⁻³ of maximum output power density. Based on electron balance calculation, 60-65% of all the electrons produced from anodic biooxidation were consumed in the cathodic bioelectro-Fenton process. This coupled system has a potential for enhanced treatment of high strength wastewater and provides a new way for efficient utilization of the electron generated from biooxidation of organic matters.     

Effect of wastewater step-feeding on removal efficiency of pilot-scale horizontal subsurface flow constructed wetlands

The performance of a pilot-scale horizontal subsurface flow (HSF) constructed wetland is investigated with emphasis on the effects of wastewater step-feeding. One pilot-scale unit, of dimensions 3 m in length and 0.75 m in width, operated continuously from January 2004 until February 2007. The unit contained cobbles obtained from a river bed and was planted with common reed (Phragmites australis). Synthetic wastewater was introduced to the unit. During the first two years of operation (period A) one inflow point was used at the upstream end of the unit. During the third year of operation (period B), wastewater step-feeding was adopted. Wastewater was introduced to the unit through three inlet points: one at the upstream end of the unit length and the other two at 1/3 and 2/3 of the unit length. Two wastewater step-feeding schemes were examined during the second working period: 33:33:33 and 60:25:15. Three HRTs (6, 8 and 14 days) were applied; wastewater temperatures varied from 6.0 to 25.0 °C. On the whole, the adoption of step-feeding in a HSF CW may be positive if an appropriate scheme is selected. Indeed, the removal of organic matter (BOD₅ and COD), nitrogen (TKN and ammonia) and phosphorus (Total Phosphorus and ortho-phosphate) was improved under the step-feeding Scheme 60:25:15, while the other scheme (33:33:33) affected negatively the wetland performance.