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Effluent reuse is a rapidly growing field of research where assessing the quality of effluent is one of the focus areas. This research examines the viability of using wastewater in agriculture by testing an integrated Upflow Anaerobic Sludge Blanket (UASB) reactor with a trickling filter (TF) system during the dry season. Compliance monitoring was conducted for 30 days from May 11 to June 9 of 2021. Samples were collected, handled, and analyzed following standard wastewater analysis procedures for biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), volatile suspended solids (VSS), cations, anions, heavy metals, E. coli, and helminth egg. The UASB-TF system in Kality wastewater treatment performed well in removing COD, BOD5, and TSS with average removal rates of 80.5%, 82.9%, and 80.9%, respectively, compared well with similar treatment configurations. The effluent quality satisfied the national inland discharge limit with a residual concentration of 125.1 mg/L for COD, 61.7 mg/L for BOD5 and 85.8 mg/L for TSS. On the other hand, high concentrations of chromium, nitrate-nitrogen, and helminth egg count restricted effluent reuse for agricultural purposes due to high health risks and environmental contamination. We found out that discharging industrial sewage into the domestic sewer network could inhibit microbial growth and affect the biological treatment processes. Furthermore, adopting integrated treatment systems in developing countries might face operational challenges and monitoring nitrate, helminth egg, and heavy metals would help provide timely operational feedback. An appropriate tertiary treatment unit—constructed wetlands or polishing ponds—is therefore needed to be introduced to ensure effluent reuse for agricultural purposes. [ABSTRACT FROM AUTHOR]

Abstract Developing countries demand a sewage treatment plant with low-cost processes that are viable in warm climates. The UASB (upflow anaerobic sludge blanket) associated with the trickling filter (TF) would meet this requirement. However, there is still a need for studies aimed at the use of new support media. Based on this, the use of expanded polystyrene (EPS) as a support media in TF was evaluated in this study. As a result, the TF filled with EPS presented a final effluent with quality similar to reactors filled with crushed stone or patented materials. The density of EPS (6.56 ± 0.30 kg m−3), the void ratio (61.7 ± 2.1%), and the mean surface area (201.9 ± 14.9 m2 m−3) once again demonstrate that EPS has characteristics similar to other alternative or patented materials. Therefore, we found that EPS can be another alternative material to be used in sewage treatment, and also that one could give an appropriate destination to a portion of this material, which is currently still discarded in landfills.

Developing countries demand a sewage treatment plant with low-cost processes that are viable in warm climates. The UASB (upflow anaerobic sludge blanket) associated with the trickling filter (TF) would meet this requirement. However, there is still a need for studies aimed at the use of new support media. Based on this, the use of expanded polystyrene (EPS) as a support media in TF was evaluated in this study. As a result, the TF filled with EPS presented a final effluent with quality similar to reactors filled with crushed stone or patented materials. The density of EPS (6.56 ± 0.30 kg m−3), the void ratio (61.7 ± 2.1%), and the mean surface area (201.9 ± 14.9 m2 m−3) once again demonstrate that EPS has characteristics similar to other alternative or patented materials. Therefore, we found that EPS can be another alternative material to be used in sewage treatment, and also that one could give an appropriate destination to a portion of this material, which is currently still discarded in landfills. [ABSTRACT FROM AUTHOR]

The present study reports a detailed life cycle assessment and cost–benefit analysis of a commercially viable Internal-Stack-Trickling Bio-Electrochemical Reactor (IS-TrickBER). IS-TrickBER used wastewater as a feedstock and converted that wastewater through electrochemical methods into low-grade fertilizer and produced electricity. IS-TrickBER was observed for its performance in terms of power output and wastewater treatment. IS-TrickBER exhibited up to 4.2 Wh net energy yield while treating 84.84L wastewater per day along with 92.17% COD removal and 38.23% Columbic efficiency during the operational run with real municipal wastewater. Based on daily net energy yield, up to 1457.6Wh yearly net energy yield can be expected. A comprehensive start-to-end life cycle assessment study associated with the manufacturing, and operational phases of IS-TrickBER was also conducted to ascertain its impact on the environment. The environmental impact through air emissions during the manufacturing stage can be minimized by changing the plastic balls used as packing material in the reactor. A detailed cost–benefit analysis was also conducted to understand its economic viability. Cost–benefit analysis of IS-TrickBER, based on net energy yield, shows that IS-TrickBER could compensate its installation cost within a few years. IS-TrickBER performed well in eliminating the chemical load of wastewater and simultaneous electricity generation. Due to its scalability, compactness, and low maintenance, IS-TrickBER can be a suitable candidate in real-time wastewater treatment. [ABSTRACT FROM AUTHOR]

The research aims to study the purification performance of a local and natural material as an input or as a biological filter for treating urban domestic wastewater. For this purpose, pozzolan was used as the biofiltration support that was provided from Beni Saf located in the North-West of Algeria. Tests were carried out with a specially modified pilot unit (TE900) for wastewater treatment over a period of four months. To assess the efficiency of the treatment, two main parameters have been focused on - the height of the sprinkler filter (40 cm and 80 cm) and the flow rate (10, 16, and 25 dm3·h-1). Physicochemical and bacteriological analyses were carried out on raw wastewater and treated water. The obtained results show that the Beni Saf pozzolan-filled trickling filter eliminates a large fraction of the studied pollutants. The purification yields obtained are fairly encouraging; 98% for turbidity, 88% for suspended solids (SS), 94% for chemical oxygen demand (COD), and 98% for biological oxygen demand (BOD5). As for bacterial indicators, the formation of biofilms has significantly reduced bacterial activity with a percentage of over 80%. It can be concluded that the reduction of pollutant parameters clearly indicates the effectiveness of the treatment by this ecological process. Therefore, the use of local and natural materials for wastewater treatment can be a promising alternative based on sustainable environmental technologies and development. [ABSTRACT FROM AUTHOR]

A pilot scale trickling filter system was designed, developed, and operated using a constant recirculation method for treatment of municipal wastewater. Maize cob (TF1) and date palm fibre (TF2) were used as biofilm support media in a trickling filter system. Both the TF1 and TF2 were compared based on the removal efficiency of pollution indicators such as biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), electrical conductivity (EC), total nitrogen (TN), total phosphorus (TP) and sulphates. The hydraulic flow rate and loading were set as 0.432 m3/h and 0.0064 m3/m2.minute, respectively at temperature range of 15–42 °C for 15 operational weeks. Both the TF1 and TF2 showed acceptable removal efficiency (61% to 76.3%) for pathogen indicators such as total count, fecal coliforms and Escherichia coli. However, 8–15% higher removal efficiency was observed for TF1 for all the pollution indicators compared to TF2. The results suggest that both the biofilm support media in trickling filter have potential to treat municipal wastewater in peri-urban small communities to produce environmentally friendly effluent. HIGHLIGHTS Agricultural waste-based biofilm support media.; Removal of carbonaceous and nitrogenous contaminants.; Log reduction of pathogen indicators.; Maize cob media is more efficient than date palm fiber.;

Optimization of operational parameters of wastewater treatment system using the modeling technique may lead to enhance the system's operational and treatment efficiency. The present research was carried out to investigate the treatment efficiency of conventional trickling filter (CTF) and cascade cum trickling filter (CCTF) for treatment of domestic wastewater. Both the systems (CTF and CCTF) were operated for a period of four months under temperature range of 21–48 °C. The maize cob (MC) and date palm fibre (DPF) were used as biofilm support media. Biological oxygen demand (BOD) reaction kinetic model was developed and evaluated for optimization of BOD removing efficiency of CTF and CCTF. The removing efficiency of CTF and CCTF has increased with increasing operational time from 12 to 48 h. The CCTF showed 3–25% higher efficiency in removing organic matter, nutrients and sulphates compared to CTF regardless the supporting media. Similarly, MC showed 3–8% higher removal efficiency of the tested parameters compared to the DPF as supporting media in both CTF and CCTF systems. The BOD reaction kinetic model estimated the optimal volumetric design BOD loading rates (Bvd) of 1.5–2.1 kg BOD/m3 day for designing efficient trickling filter systems. The CCTF with MC media was found efficient than other reactors due to highest BOD removal efficiency (91.8%) and good capacity to treat high BOD load (2.1 kg/m3.day). Hence, the CCTF system has higher potential for efficient removal of organic and inorganic contaminants from the wastewater in developing countries. [ABSTRACT FROM AUTHOR]

Bioelectrochemical systems such as microbial fuel cells are novel systems; those directly transform the chemical energy contained in organics of wastewater into electrical energy by the metabolic action of the microbial community. During the last two decades, bioelectrochemical systems astonishingly increased their wastewater treatment capabilities, sustainability, and power output. However, studies on scalable architectural designs of bioelectrochemical systems received less attention. Lower power yield and high cost are two major limitations for scaling up of bioelectrochemical systems. This study reports a low cost, scalable, air cathode bio-electrochemical reactor, constructed by adopting a trickling filtration approach (TrickBER) and operated in continuous mode. Various facets of construction, installation, and operation of TrickBER were investigated and optimized to achieve an efficient performance. TrickBER was found suitable in simultaneous electricity generation during continuous wastewater treatment and, in the future, could be used in small/cottage industries. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main objective of wastewater treatment is to remove carbon and other nutrients from municipal and industrial effluents in order to protect the environment and human health. Typical wastewater treatment is usually achieved by a combination of physical, chemical and biological methods. In this work, municipal wastewater was depurated using chemically enhanced primary treatment (CEPT) in combination with a pilot-scale trickling filter. Lab scale experiments (Jar-tests) were carried out in order to determine the optimum dosage of chemicals. Selection criteria were the organic load removal efficiency and the low operational cost. Coagulation-flocculation process was conducted through polyaluminium chloride (PAC) and the cationic polyelectrolyte (Zetag 8180) addition. By combining CEPT and trickling filter, tCOD (total Chemical Oxygen Demand), sCOD (soluble Chemical Oxygen Demand), BOD5 (5-day Biochemical Oxygen Demand), NH4+-N, TSS (Total Suspended Solids), VSS (Volatile Suspended Solids) and PO43−-P removal efficiencies were estimated to be 89, 82, 93, 60, 96, 96 and 78%, respectively. It is concluded that biological filtration contributed significantly in nutrients removal processes. Moreover, the obtained effluent was low in carbon and rich in nitrogen, which can be applied for restricted irrigation after disinfection, complying with the discharge limits set in the Greek Joint Ministerial Decree 145116/2011. [ABSTRACT FROM AUTHOR]

Despite the global water crisis, the significant potential of trickling filter systems as a crucial auxiliary option for sustainable water supply has received insufficient attention. Therefore, this study presents the first-ever evaluation of the environmental impacts of trickling filter application in wastewater treatment, focusing on eco-environmental burdens. Additionally, the study explores greenhouse gas emissions, energy, and exergy footprints, providing novel insights into the environmental implications of using trickling filters for wastewater treatment. The study's findings indicate that the consumption of heat and electricity in trickling filters has significant environmental impacts, particularly on land use (93.24%), freshwater/marine eutrophication (∼81.98%), and human health (45.36%). The majority of the energy required for trickling filter operation is supplied by fossil fuels (96.02%), resulting in increased greenhouse gas emissions (65.58%). The exergy of trickling filters is highly efficient, accounting for over 95% of the system's energy. Mathematical modeling reveals that anaerobic digestion and secondary clarifier have the highest energy consumption, with contributions of 94.65% and 2.63%, respectively. Construction expenses account for almost 88% of the total cost, with anaerobic digestion (42.15%) and trickling filters (35.39%) being the most costly components. The cost of treating 1 m3 of wastewater is estimated at 0.52 $/m3. Sensitivity analysis demonstrates that electricity (14.66%) and heat (18.65%) significantly impact terrestrial ecotoxicity and land use, respectively. This study presents a framework for future investigations in this field. • The most TF environmental burdens related to heat (54.24%) and electricity (10.26%). • More than 80% of the total costs were consumed for the construction phase. • The cost of 1 m3 wastewater treatment using TF was 0.52 $/m3. • The exergy analysis indicated a significant contribution of natural gas (60.88%). • The anaerobic digester was the main contributor to the energy footprint (94.65%). [ABSTRACT FROM AUTHOR]

The presence of active pharmaceutical ingredients (APIs) in the environment is of growing concern and effluents from wastewater treatment works (WwTWs) are one of the major sources. This research combines the outputs of a multimillion pound UK program of work to evaluate the fate of APIs in the wastewater treatment process. A combination of analysis of measured data and modelling has been applied to 18 APIs, representing a wide range of medicinal application and physico-chemical characteristics. Some isomers (for atorvastatin) and metabolites (for sertraline, carbamazepine and erythromycin) were also included. High variability was observed between removal rates for individual APIs between WwTW, which after statistical analysis could not be explained by the nominal WwTW process (e.g. activated sludge or trickling filter). Nor was there a clear relationship between API removal and physico-chemical parameters such as pKa, charge or log Kow. A publically available sewage process model, SimpleTreat 4.0 which has been rigorously validated and is now being used for exposure assessment with REACH legislation for organic chemicals and within the Biocidal Products Regulation by the European Medicines Agency for APIs, was used to estimate removal rates with which to compare with measured data. SimpleTreat provided estimates of removal rates within ±30% of observed values for the majority of the APIs measured, with the use of readily available WwTW specific parameters such as flow, total suspended solids and BOD data. The data and correlations provided in this study provide support for any future considerations regarding the management of API discharge to the aquatic environment. Unlabelled Image • Removal efficiency data for 19 pharmaceuticals and 4 metabolites in 45 UK sewage works • Activated sludge vs trickling filter works performance not significantly different • Removal not simply explained by phys-chem characteristics of pharmaceutical • Removal poorly correlated to sewage works sanitary determinands • SimpleTreat model capable of predicting removal to within 30% of measured values [ABSTRACT FROM AUTHOR]

The article presents the results of the research on the possibility of using a trickling filter for high efficiency treatment of dairy sewage. Nowadays, to the best of the authors' knowledge, it is possible to change the activated sludge system to the trickling filter technology, especially in small dairy plants with lower raw sewage parameters in comparison to larger plants. In the research, dairy wastewater after dissolved air flotation (DAF) process was treated with a laboratory scale Gunt CE701e research model which allows to control the basic parameters of the treatment with a trickling filter (TF). The conducted study included determining the changing sewage parameters during the DAF process, as well as the trickling filter (TF) efficiency. Such parameters as Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), total Organic Carbon (TOC), total Kjeldahl nitrogen (TKN) and total phosphorous (TP) were checked. The research results confirmed the possibility of high efficiency treatment of dairy sewage with DAF and trickling filter technologies. The average efficiency of DAF treatment was 59.3% for BOD, 49.0% for COD and 80.0% for TP, while the average treatment efficiency of TF was 87.3%, 78.3% and 27.9% without recirculation and 95.2%, 85.5% and 42.0% with 100% recirculation applied, respectively. The load of TF during the operation without recirculation was on average 0.22 kgBOD5·m-3·d-1 and 0.25 with 100% recirculation. Applying recirculation allowed to reach the BOD, COD and total phosphorus standards for the sewage discharged to a receiver from Bielmlek dairy WWTP. On the other hand, the concentration of total nitrogen exceeded the permitted standards in this facility. [ABSTRACT FROM AUTHOR]

The naproxen-degrading bacterium Bacillus thuringiensis B1(2015b) was immobilised onto loofah sponge and introduced into lab-scale trickling filters. The trickling filters constructed for this study additionally contained stabilised microflora from a functioning wastewater treatment plant to assess the behavior of introduced immobilized biocatalyst in a fully functioning bioremediation system. The immobilised cells degraded naproxen (1 mg/L) faster in the presence of autochthonous microflora than in a monoculture trickling filter. There was also abundant colonization of the loofah sponges by the microorganisms from the system. Analysis of the influence of an acute, short-term naproxen exposure on the indigenous community revealed a significant drop in its diversity and qualitative composition. Bioaugmentation was also not neutral to the microflora. Introducing a new microorganism and increasing the removal of the pollutant caused changes in the microbial community structure and species composition. The incorporation of the immobilised B1(2015b) was successful and the introduced strain colonized the basic carrier in the trickling filter after the complete biodegradation of the naproxen. As a result, the bioremediation system could potentially be used to biodegrade naproxen in the future.

This study aimed to characterize raw municipal and dairy wastewaters. The quality of the collected wastewaters was determined by measuring 30 quality parameters, such as phenols, oxidation-reduction potential, oil and grease, total organic carbon (TOC), manganese, total viable count of bacteria (TVC), salinity, and biodegradability. Results were compared with wastewater disposal standards. This study also aimed to describe the potential application and performance of biological trickling filters (BTFs) in municipal and dairy wastewater treatment. Detailed reviews of trickling filter models were explained. Results revealed that two wastewater samples exceeded standard limits. The raw municipal and dairy wastewaters need treatment prior to disposal to the natural environment. Additionally, BTFs are efficient municipal and dairy wastewater treatments. [ABSTRACT FROM PUBLISHER]

The effects of floc structural characteristics, i.e. shape and dense biomass distribution, were evaluated on ultraviolet (UV) disinfection resistance, represented by the tailing level of the UV dose response curve (DRC). Ellipsoid-shaped flocs of similar volume and different projected circularities were constructed in-silico and a mathematical model was developed to compare their UV DRC tailing levels (indicative of UV-resistance). It was found that floc shape can significantly influence tailing level, and rounder flocs (i.e. flocs with higher circularity) were more UV-resistant. This result was confirmed experimentally by obtaining UV DRCs of two 75–90 μm floc populations with different percentages (20% vs. 30%) of flocs with circularities higher than 0.5. The population enriched in less circular flocs (i.e. 20% flocs with circularities >0.5) had a lower tailing level (at least by 1-log) compared to the other population. The second model was developed to describe variations in UV disinfection kinetics observed in flocs with transverse vs. radial biomass non-homogeneity, indicative of biofilm-originated vs. suspended flocs. The varied-density hemispheres model and shell-core model were developed to simulate transverse and radial non-homogeneity, respectively. The UV DRCs were mathematically constructed and biofilm-originated flocs showed higher UV resistance compared to suspended flocs. The calculated UV DRCs agreed well with the experimental data collected from activated sludge and trickling filter flocs (no fitting parameters were used). These findings provide useful information in terms of designing/modifying upstream processes for reducing UV disinfection energy demand. [ABSTRACT FROM AUTHOR]

The abundance of ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) was investigated in full-scale two-stage trickling filters (TF) and moving bed bioreactor (MBBR) treating municipal wastewater. Biofilm samples were collected for 17 months from nitrifying TF (NTF), biochemical oxygen demand TF (BTF), and MBBR media. The abundance of AOA and AOB was determined using a quantitative PCR approach targeting the ammonia monooxygenase subunit A gene of archaea and bacteria. AOA were dominant in the NTF and MBBR, while AOB dominated in the BTF. AOA and AOB were more abundant during warmer months, and AOA were detected in the BTF only during warmer months. In laboratory nitrification activity experiments, ammonia oxidation to nitrite decreased when AOA populations from the NTF and MBBR were inhibited, demonstrating that AOA contributed to nitrification. This study has shown that AOA outnumber AOB and contribute to ammonia oxidation in full-scale nitrifying biofilm processes. [ABSTRACT FROM AUTHOR]

Anaerobic digesters generate effluent containing about 3000 mg L-1 of organic matter in terms of chemical oxygen demand (COD). This effluent must be treated before being reused or discharged into the environment. The objective of this study was to evaluate the efficiency of a trickling filter packed with red volcanic rock for the treatment of anaerobic digester effluent with COD concentrations of around 3000 mg L-1. The trickling filter consisted of an aluminum cylinder, 2 mm thick, 3 m high, and 1 m in diameter. To evaluate the efficiency of the treatment system, there were three experimental runs, each lasting 20 days (d). The predictor variable was the initial COD concentration, which ranged from 2002 to 3074 mg L-1. The hydraulic retention time was 9 h. The influent flow was 2.2 L min-1, which amounts to a hydraulic load of 4033 m³ m-2 day-1 and an organic load of 0.006342 to 0.009738 kg m-3 day-1 of COD. Independent of the initial concentration, COD removal efficiency was very high, varying from 90 to 96%. Final effluents met all the maximum permissible limits to be used as irrigation water, as well as for its release into natural or artificial water reservoirs, stored for agricultural crop irrigation. [ABSTRACT FROM AUTHOR]

The need of wastewater (WW) treatment is increasing along with the production of WW and its disposal without treatment. With a smaller footprint, ease of operation, and relatively less cost, trickling filter (TF) wastewater treatment systems have been considered to be more adoptable for domestic and industrial WW treatment in underdeveloped and/or developing countries - particularly for Asia and Africa. A relatively lowcost and operationally effective TF wastewater treatment system was developed using farm waste cotton sticks as biofilm support media. During the operation of the TF system, flow rates vary from 1.7 to 4.6 m3/hr. The attained removal efficiency for BOD (biological oxygen demand) was 69-78% and for chemical oxygen demand (COD) was 65-80%. The solids removal in TF system was 38-56% for total suspended solids (TSS) and 20-36% for total dissolved solids (TDS). Other aggregates such as turbidity and color removal were 32-54% and 25-42%, respectively. Four to five months of trouble-free operation of the developed TF system indicated the robustness and reliability of the system. Cotton sticks appeared to be a degradation-resistant alternative filter media for the TF system. Moreover, it is useful for reducing potential impacts of WW re-use at the farm level. Treated effluents through the TF system can be re-used as an irrigation water supplement in under-developed and/or developing countries. [ABSTRACT FROM AUTHOR]

Ozonation and three (biological) filtration techniques (trickling filtration (TF), slow sand filtration (SSF) and biological activated carbon (BAC) filtration) have been evaluated in different combinations as tertiary treatment for municipal wastewater effluent. The removal of 18 multi-class pharmaceuticals, as model trace organic contaminants (TrOCs), has been studied. (Biological) activated carbon filtration could reduce the amount of TrOCs significantly (>99%) but is cost-intensive for full-scale applications. Filtration techniques mainly depending on biodegradation mechanisms (TF and SSF) are found to be inefficient for TrOCs removal as a stand alone technique. Ozonation resulted in 90% removal of the total amount of quantified TrOCs, but a post-ozonation step is needed to cope with an increased unselective toxicity. SSF following ozonation showed to be the only technique able to reduce the unselective toxicity to the same level as before ozonation. In view of process control, innovative correlation models developed for the monitoring and control of TrOC removal during ozonation, are verified for their applicability during ozonation in combination with TF, SSF or BAC. Particularly for the poorly ozone reactive TrOCs, statistically significant models were obtained that correlate TrOC removal and reduction in UVA254 as an online measured surrogate parameter. [ABSTRACT FROM AUTHOR]

A full-scale study has been conducted to assess the bioaugmentation efficiency of trickling filter process to treat petrochemical wastewater from a lubricant industry recycling waste oils. During 45 weeks, the organic loading rate (OLR) in the trickling filter was increased stepwise from 0.9 to 4 kg of chemical oxygen demand (COD)/(m³-day) at the end of the upgrading period as the flow rate (FR) reached the value of 30 m³/day. The removal, obtained in terms of percentage, for COD ranged from 60 to 84.5 and greater than 98 for total n-alkane (TNA), while those of total kjeldahl nitrogen (TKN) and total phosphor (TP) were about 32 and 55, respectively. The analytical profile index (API) of trickling biofilm has confirmed that 5 strains are closely related to Acinobacter junii, Stenotrophomonas maltophilia, Vibrio vulnificus, Vibrio metschnikovi, Pseudomona slulzeri and Trichosporon spp2. [ABSTRACT FROM AUTHOR]

In developing countries, good-quality water is contaminated due to the disposal of untreated municipal and industrial wastewater (WW) into natural water reservoirs. Most of the wastewater is not treated properly according to international standards, and usually is disposed of and/or utilized for irrigation without appropriate treatment. The main hurdles in providing wastewater treatment (WWT) in developing countries include high costs, and the poor design, installation, and operation of conventional WWT systems. Therefore, the present study explores the maize cobs trickling filter-based (MCTF) low-cost WWT option for developing countries like Pakistan, India, and Bangladesh. In this regard, indigenous media trickling filter was designed and developed using maize cobs as packing material for biofilm growth. The MCTFWWT system was continually operated and monitored for six months at constant hydraulic wastewater loading of about 113±2 m3 per m2 per day. The experimental data covers winter and summer seasons with temperature variations from 23°C to 43°C. System performance was evaluated by means of various WWT parameters, including biological and chemical oxygen demands (BOD5 and COD), total suspended and dissolved solids (TSS and TDS), turbidity, and color - before and after WWT. Experimental results showed that the MCTF-WWT system successfully removed about 79% BOD and 75% COD on average. The key reason for effective BOD and COD removal was rapid development of microbial film (within the first two weeks). Furthermore, the MCTF-WWT system removed 42-46% TSS, 28-30% TDS, 43-46% turbidity, and 33-37% color. The study concludes that the MCTF-WWT system is an effective and economical WWT option for irrigation/agricultural applications in developing countries. [ABSTRACT FROM AUTHOR]

Wastewater treatments are considered important means to control the environmental transmission of human norovirus (NoV). Information about NoV concentrations in untreated and treated effluents, their seasonality and typical removal rates achieved by different treatment processes is required to assess the effectiveness of sewage treatment processes in reducing human exposure to NoV. This paper reports on a characterisation of concentrations of NoV (genogroups I and II) in untreated sewage (screened influent) and treated effluents from five full scale wastewater treatment works (WwTW) in England. Results are shown for effluent samples characteristic of primary- (primary settlement, storm tank overflows), secondary- (activated sludge, trickling filters, humus tanks) and tertiary (UV disinfection) treatments. NoV occurrence in untreated sewage varied between years. This variation was consistent with the annual variation of the virus in the community as indicated by outbreak laboratory reports. Significant differences were found between mean NoV concentrations in effluents subject to different levels of treatment. Primary settlement achieved approximately 1 log 10 removal for both genogroups. Concentrations of NoV and Escherichia coli in untreated sewage were of the same order of magnitude of those in storm tank overflows. Of the secondary treatments studied, activated sludge was the most effective in removing NoV with mean log 10 removals of 3.11 and 2.34 for GI and GII, respectively. The results of this study provide evidence that monitoring of NoV in raw sewage or treated effluents could provide early warning of an elevated risk for NoV and potentially help prevent outbreaks through environmental exposure. They also provide evidence that elimination of stormwater discharges and improvement of the efficiency of activated sludge for NoV removal would be effective for reducing the risk of environmental transmission. [ABSTRACT FROM AUTHOR]

In the modified Ludzack-Ettinger process, high-energy input is required in a nitrification tank. To address this issue, a new biological nitrification-denitrification system was constructed with a trickling filter for nitrification. The effects of recirculation rate of nitrified liquor and temperature through the treatment of municipal wastewater were evaluated. The highest DN removal efficiency was observed at 6.5 h of hydraulic retention in the denitrification tank and 350% of recirculation rate of nitrified liquid against the influent flow rate. The DN removal efficiencies did not reach theoretical values for all conditions tested because the COD/N ratios in the influent often decreased to less than 5 g-COD/g-N and temperatures dropped to less than 15°C in winter. The former inhibited the denitrification process and the latter significantly decreased the bioactivity of nitrifying bacteria. As such, this system is suitable in tropical and subtropical areas with annual minimum temperatures of over 15°C. [ABSTRACT FROM AUTHOR]

This study aimed at developing and evaluating techniques for the development of automatic control systems for wastewater treatment systems involving trickling filter. The proposed control systems were established from the application of Optimal Control Theory, considering the use of a simplified dynamic model of the trickling filter. Computer simulations were used to assess the performance of the control systems proposed. The results showed that the dynamic model of the trickling filter utilized in this study was stable and suitable for the definition of control systems. [ABSTRACT FROM PUBLISHER]

To better understand pharmaceutical fate during wastewater treatment, analysis in both aqueous and particulate phases is needed. Reported herein is a multi-residue method for the determination of ten pharmaceutical drugs and the personal care product triclosan in wastewater matrices. Method quantitation limits ranged from 7.6 to 76.6 ng l − 1 for aqueous phases and from 7.0 to 96.7 ng g − 1 for particulate phases. The analytical method was applied to attain a complete process mass balance of a pilot-scale activated sludge plant (ASP) operated under controlled conditions. The mass balance (inclusive of aqueous and particulate concentrations at all sample points) was used to diagnose removal, revealing pharmaceuticals to be separable into three fate pathways: (a) biological degradation, (b) sorption onto activated sludge and (c) resistant to removal from the aqueous phase. These differences in fate behaviour explained a broad range of secondary removal observed (− 8 to 99%). The ASP was also simultaneously compared to a full-scale trickling filter (TF) works whilst receiving the same influent wastewater. Performance of the ASP and TF was similar, achieving total pharmaceutical removals of 253 and 249 μg g − 1 biochemical oxygen demand (BOD) removed, respectively. This corresponded with reductions in total pharmaceutical load of 91 and 90% (ANOVA, p - value > 0.05). Interestingly, despite low suspended solid concentrations final effluents of both the ASP and TF contained significant concentrations of some chemicals in the particulate phase. Individually, triclosan and the antibiotics ofloxacin and ciprofloxacin were within the particulate phase of effluents at concentrations ranging from 26 to 296 ng l − 1 . [ABSTRACT FROM AUTHOR]

The use of vertical flow constructed wetlands (VFCW) is growing rapidly in Europe for domestic wastewater treatment in small communities. In order to improve denitrification and dephosphatation as compared to classical VFCW, the Azoé-NP ® process has been developed. The process line consists of: a biological aerobic trickling filter as a primary treatment stage, ferric chloride (FeCl 3 ) addition for phosphorus (P) treatment and two stages of partially saturated VFCW. A municipal wastewater treatment plant using Azoé-NP ® process has been monitored during eight years through 44 campaigns of 24 h time-proportional inlet–outlet sampling followed by analyses of TSS, BOD 5 , COD, TKN, NO 3 –N and TP concentrations. The results revealed good performances of the overall treatment. To better characterize the performance of each treatment step, five additional 24 h monitoring campaigns were performed with samples taken from four different points along the treatment line. Results showed a good performance in dissolved carbon removal and nitrification by the trickling filter. The main part of the treatment was found to be done by filtration throughout the first filtration stage. Nitrate removal was achieved principally at the second filtration stage. Phosphorus migration through the first stage and its slight retention at the second stage was observed. [ABSTRACT FROM AUTHOR]

The performance of trickling filters using two types of plastic media with the same material, the same shape and different roughness was evaluated during a temperature-decreasing period to understand the roughness and temperature effects on the filter media. Real restaurant wastewater was used for the experiments. The chemical oxygen demand (COD) removal and nitrification performance of plastic media with a rough surface (LT-15) was superior to that with a smooth surface (KT-15). Because the biomass of microorganisms attached on the LT-15 was twice that attached on the KT-15, the larger biomass attached on the LT-15 was thought to be responsible for the higher performance. During the operation, the COD loading and water temperature varied in the range from 0.37 to 1.9 kg m−3 d−1and 17.0−10.0°C, respectively. However, the COD removal performance was not dependent on the COD loading or water temperature. On the contrary, the COD loading and the water temperature influenced the nitrification performance. Although a nitrification efficiency of 100% was recorded at a COD loading of 0.37 kg m−3 d−1, it deteriorated to 17–28% at higher COD loading. Moreover, a decline in the water temperature decreased the nitrification performance. The temperature-activity coefficient for nitrification was estimated to be 1.096. Based on this value, it was inferred that the COD loading should be set at less than 0.20 kg m−3 d−1for the complete nitrification of the restaurant wastewater in winter, when the water temperature usually drops to around 10°C. [ABSTRACT FROM PUBLISHER]

Wastewater treatment plants use a variety of bioreactor types and configurations to remove organic matter and nutrients. Little is known regarding the effects of different configurations and within-plant immigration on microbial community dynamics. Previously, we found that the structure of ammonia-oxidizing bacterial (AOB) communities in a full-scale dispersed growth activated sludge bioreactor correlated strongly with levels of NO entering the reactor from an upstream trickling filter. Here, to further examine this puzzling association, we profile within-plant microbial biogeography (spatial variation) and test the hypothesis that substantial microbial immigration occurs along a transect (raw influent, trickling filter biofilm, trickling filter effluent, and activated sludge) at the same full-scale wastewater treatment plant. AOB amoA gene abundance increased >30-fold between influent and trickling filter effluent concomitant with NO production, indicating unexpected growth and activity of AOB within the trickling filter. Nitrosomonas europaea was the dominant AOB phylotype in trickling filter biofilm and effluent, while a distinct ' Nitrosomonas-like' lineage dominated in activated sludge. Prior time series indicated that this ' Nitrosomonas-like' lineage was dominant when NO levels in the trickling filter effluent (i.e., activated sludge influent) were low, while N. europaea became dominant in the activated sludge when NO levels were high. This is consistent with the hypothesis that NO production may cooccur with biofilm sloughing, releasing N. europaea from the trickling filter into the activated sludge bioreactor. Phylogenetic microarray (PhyloChip) analyses revealed significant spatial variation in taxonomic diversity, including a large excess of methanogens in the trickling filter relative to activated sludge and attenuation of Enterobacteriaceae across the transect, and demonstrated transport of a highly diverse microbial community via the trickling filter effluent to the activated sludge bioreactor. Our results provide compelling evidence that substantial immigration between coupled process units occurs and may exert significant influence over microbial community dynamics within staged bioreactors. [ABSTRACT FROM AUTHOR]

Highlights: [•] Thin iron scraps layer paved in the trickling filter enhanced the TP removal. [•] Zeolite trickling filter under intermittent water feeding benefits nitrification. [•] Coarse media in the first stage inhibits clogging of the latter infiltration stage. [•] Better influent dispersion for MSL was achieved owing to the two-stage design. [•] Two-stage filter system appeals to decentralized treatment of sewage well. [ABSTRACT FROM AUTHOR]

The century-old trickling filters at the Daspoort Wastewater Treatment Works in Pretoria (Gauteng, South Africa) are known for their remarkable removal of nitrogen from municipal wastewater. Our study was conducted to identify the microbiological processes responsible for this phenomenon and to establish whether anammox bacteria may be involved. An aerobic and anaerobic bench top reactor, both inoculated with biofilm-covered stones from one of the filters, were spiked with ammonia-nitrogen (NH4+-N) and nitrite-nitrogen (NO2--N). These reactors were subsequently monitored by conducting stoichiometric analyses of chemical oxygen demand (COD), NH4+-N, NO2--N, and nitrate-nitrogen (NO3--N). In the aerobic reactor, the COD concentration decreased over the 56 h batch reaction period and nitrification was revealed by a decrease in NH4+-N and NO2--N concentrations. However, the NO3--N concentration showed no notable decrease. In contrast, in the anaerobic reactor the concentrations of COD, NH4+-N, NO2--N, NO3--N, as well as total nitrogen decreased during the batch reaction period. The decrease of both the NH4+-N and NO2--N concentrations, the latter to zero under anaerobic conditions, suggested that, in addition to heterotrophic denitrification, anaerobic ammonium oxidation (anammox) may also occur in the trickling filter biofilm. This was highlighted by the observation that ammonium removal in the anaerobic reactor stopped as soon as the nitrite concentration became zero. The ratio of nitrite:ammonium removal was 1.33 on average, which conforms to anammox behaviour. Gene sequence analysis was used to test for the possible presence of anammox bacteria in the trickling filter biofilm. Genomic DNA was extracted from trickling filter humus sludge and the polymerase chain reaction (PCR) was used to amplify taxonomically informative 16S rRNA gene sequences, using primers specific for selected anammox species. Subsequent sequence analysis, including using the online Basic Local Alignment Search Tool (BLAST), and constructing a phylogenic tree using a heuristic search strategy for Maximum Parsimony analysis, confirmed the presence of an anammox bacterium closely related to Candidatus 'Brocadia anammoxidans' and Candidatus 'Brocadia fulgida' on the biofilm-covered stones of the Daspoort trickling filters. [ABSTRACT FROM AUTHOR]

The fate and behaviour of tributyltin (TBT) at two wastewater treatment works was examined. Both sites had two inlet streams, and each utilised high rate biological filters (biofilters) on one the streams, before treatment of the combined flows on trickling filters, with one having additional tertiary processes, installed to remove ammonia and solids. The study was designed to determine if these processes enhanced the removal of TBT. Degradation of TBT was observed in one of the biofilters, possibly as a result of temperature and hydraulic loading. At the treatment works with tertiary processes, the mass flux showed the overall removal of TBT was 68 %, predominantly due to removal with solids in the primary settlement processes. However, overall removal of 95 % was observed in the conventional trickling filter works with 94 % of this due to biodegradation in the trickling filter. The two works both removed TBT, but at different treatment stages and by different processes. Differences in the form (solubility) of TBT in the influent may have attributed to this, although further understanding of factors controlling degradation would allow for a more complete assessment of the potential of biological processes to remove hazardous compounds from wastewaters. [ABSTRACT FROM AUTHOR]

Effective wastewater purification in subsurface flow constructed wetlands must include adequate pretreatment and ensure a sufficient amount of dissolved oxygen. In a pilot-scale operation, a subsurface flow constructed wetland (CW) consisted of a primary settlement tank, a trickling filter for pretreatment and two serially assembled basins. The trickling filter was added to ensure sufficient aeration, increase purification of the wastewater and shorten the wastewater purification time. The estimated nominal flow was 0.7 m3/d. The experiments were conducted using the wastewater from the municipal sewage canal of the city of Zagreb, with utilization of three different flows: 0.72 (A), 1.44 (B) and 2.88 (C) m3/d. The efficiency of the purification process was monitored over a period of three years (TSS, BOD5, COD, NH4-N, NO2-N, PO4-P, dissolved oxygen, temperature and pH). The experimental results showed an increase in the removal efficiency with a doubling of the nominal flow from 0.7 to 1.44 m3/d, which could be related to the implementation of the trickling filter where high removal rates were achieved. [ABSTRACT FROM PUBLISHER]

More and more research effort has been put into the development of affordable and high-efficiency wastewater reclamation technology for small communities. In this study, an integrated chemically enhanced primary treatment (CEPT), trickling filter (TF) and ultrafiltration (UF) process was developed with success. Coagulant produced from fly ash was used to enhance primary treatment, while trickling filter packed with coal cinder through four-layer structure without aeration was employed for further removal of COD and ammonium-nitrogen from the CEPT effluent. 95 and 88% removal of COD and ammonium were achieved, while total phosphorus (TP) and suspended solid (SS) were found to be removed completely at a coagulant dosage of 2.5 mL/L in the CEPT-TF-UF system. The product water can meet the standard of Reuse of Recycling Water for Urban Water Quality Standard for Urban Miscellaneous Water Consumption (GB/T 18920-2002, China). [ABSTRACT FROM AUTHOR]

The paper analyses the concept and performance of different configurations of compact UASB/TF systems, without the final clarification stage, in relation to the removal of organic matter. The experiments were carried out in two sets of UASB/TF systems operating without secondary clarifiers, as follows: (i) four shallow (2.50 m height) TFs, each one filled with a different packing material; and (ii) two deep (4.20 m height) TFs, one filled with polyethylene corrugated sheets and the other with mixed polyethylene and sponge sheets. For the conditions tested (different packing material in shallow and deep TF), the UASB/TF systems had consistently complied (90 to 100% of the results) with the Brazilian discharge standards regarding to BOD, COD, and TSS parameters. The average BOD, COD and TSS effluent concentrations stayed below 40 mg BOD L-1, 100 mg COD L-1 and 50 mg TSS L-1, respectively. UASB/TF systems can constitute an attractive alternative for domestic wastewater treatment in small communities in developing countries, especially considering its operational simplicity and very low running costs. [ABSTRACT FROM AUTHOR]

Household on-site septic systems with secondary wastewater treatment in Anchorage. Alaska, were sampled and analyzed for performance parameters during the winter to spring months. System types included intermittent dosing sand filters (ISF), three types of recirculating trickling filters (RTF), and suspended-growth aeration tanks. Total nitrogen from the trickling filter and aeration tank effluent was fairly uniform, at approximately 30 mg/L. Total suspended solids (TSS) means were mostly less than 15 mg/L. The 5-day biochemical oxygen demand (BOD5) showed considerable variability, with means ranging from 9.2 mg/L for ISFs up to 39.5 mg/L for one type of RTF, even though this type has shown excellent results in several test programs. The data suggested that effluent temperature within the sample range had almost no effect on effluent concentrations of BOD5 or TSS and only a small effect on the removal of total nitrogen. Non-climatic factors were probably of equal importance to treatment results. [ABSTRACT FROM AUTHOR]

The application of nitrifying trickling filters (NTFs) to potable water treatment is less well understood than their application to wastewater treatment, particularly regarding the effect of low ammonia substrate concentrations and organic carbon loading on filter performance. A large pilot-scale NTF was operated under conditions that simulated the raw water quality of poorly protected catchments typically found in SE Asia, with the objective of reducing the ammonia driven chlorine demand during disinfection. The efficacy of a high rate NTF to remove low concentrations of ammonia (0.5-5.0 mg NH4-N L-1) in the presence of high organic carbon (1-12 mg soluble biochemical oxygen demand (sBOD5) L-1) was investigated. Results demonstrated that 90 to 100% of nitrification was maintained only when the carbon load was less than 0.7 g sBOD5 m-2 d-1 (<4 mg sBOD5 L-1). Once the organic load was increased beyond 0.75 to 2.1 g sBOD5 m-2 d-1 (4.5-12.1 mg sBOD5 L-1), a linear decline in nitrification from 70 to 15% was observed within a timeframe of 8 to 10 d. The impact of high organic loads on the distribution of nitrification down the NTF was also investigated. Results confirmed that carbon loads greater than 0.95 g sBOD5 m-2 d-1 (>5.5 mg sBOD5 L-1), severely suppressed nitrification throughout the entire filter bed. [ABSTRACT FROM AUTHOR]

Abstract: This chapter describes the possibility to combine wastewater treatment in recirculating aquaculture systems (RAS) with the production of crop plants biomass. In an aquaponic RAS established in Waedenswil, Zurich, the potential of three crop plants was assessed to recycle nutrients from fish wastewater. A special design of trickling filters was used to provide nitrification of fish wastewater: Light-expanded clay aggregate (LECA) was filled in a layer of 30 cm in vegetable boxes, providing both surface for biofilm growth and cultivation area for crop plants. Aubergine, tomato and cucumber cultures were established in the LECA filter and nutrient removal rates calculated during 42–105 days. The highest nutrient removal rates by fruit harvest were achieved during tomato culture: over a period of >3 months, fruit production removed 0.52, 0.11 and 0.8 gm−2d−1 for N, P and K in hydroponic and 0.43, 0.07 and 0.4 gm−2d−1 for N, P and K in aquaponic. In aquaponic, 69% of nitrogen removal by the overall system could thus be converted into edible fruits. Plant yield in aquaponic was similar to conventional hydroponic production systems. The experiments showed that nutrient recycling is not a luxury reserved for rural areas with litlle space limitation; instead, the additionally occupied surface generates income by producing marketable goods. By converting nutrients into biomass, treating wastewater could become a profitable business. [Copyright &y& Elsevier]

A compost biofilter enriched in earthworms was adapted to treat cheese whey produced by a dairy in a mountainous area of the French pre-Alps. Until now, this type of installation has only been developed in mountain pasture areas and therefore only functions during the months of mountain pasture grazing, from May to September. The main goal of this study was to follow up pollutant removal performance after more than one year of operation. During the experiment, cheese whey loading varied from a few litres to 40 L m-2 d-1. Despite variations in the physical properties of the support media after 460 days of operation, whey removal performance was good. For COD and BOD, 80-88% of the loading mass and 70-80% of nitrogen and phosphorus was removed. In this experiment, the treated effluent could not meet the standards for discharge into rivers, but was a very effective and simple pretreatment. This study confirms the observations of previous experiments in mountain pastures both in France and Switzerland: a cheese whey volume of 20 L m-2 d-1 could be a basis for design, although the process can treat up to 40 L m-2 d-1 for seven days according to our results. [ABSTRACT FROM AUTHOR]

Wastewater management in small and medium-sized enterprises representing the chemical and food industries was investigated. The results showed that wastewater discharged from an ink-production factory was highly contaminated with organic pollutants. Anaerobic biological treatment followed by chemical coagulation using ferric chloride aided with lime proved to be very effective and produced an effluent that complied with national regulatory standard for wastewater discharge into public sewage network. Also, management of wastewater from a confectionery factory representing the food sector was carried out. Aerobic biological treatment using plastic-packed trickling filter proved to be an effective treatment method. However, application of in-plant control measures alleviated the requirement for the construction of a wastewater treatment plant. The applied pollution prevention and cleaner production measures involved good housekeeping, recovery of spent chocolate, modification of floor cleaning and installation of suction devices for the removal of sugar and starch powders. All improvement measures were documented by cost/benefit analysis. [ABSTRACT FROM AUTHOR]

It is generally known that sonication improves ultraviolet (UV) disinfection kinetics of municipal effluents by breaking large suspended particles. However, the feasibility of sonication as a pretreatment technology largely depends on wastewater quality and discharge requirements. The purpose of this study was to investigate the potential benefits of ultrasound for improving the UV disinfectability of various effluent types, including primary, activated sludge, and trickling filter effluents. It was found that the tailing level of the dose-response curve at high UV doses (>40 mJ/cm²) decreased with the increased sonication time. The reduction in the tailing level had a strong correlation with the decrease in the number concentration of large particles (>60 µm) such that 1 log reduction in the number concentration of large particles resulted in 1.4, 1.1, and 1.7 log reductions in the tailing level for primary, activated sludge, and trickling filter effluents, respectively. However, the improvement in the UV disinfectability due to sonication was partly offset by the reduction in the UV transmittance of the effluent. [ABSTRACT FROM AUTHOR]

The environmental impact of endocrine disrupting chemicals (EDC) has been intensively researched over the last 10 years in the academic field. One of the observations highlighted has been the relationship between feminization of male fish (known as intersex) and the discharge of steroid estrogens from sewage treatment works (STWs). Compounds that act like estrogens found in certain industrial chemicals have also been blamed for such an effect. Given the long-term effect this may have on fish population, it is anticipated that EDC removal may be imposed in the future discharge consent to ensure the concentration not exceeding a Predicted No Effect Concentration (PNEC), taking into account the dilution capacity in the receiving water. Currently, there is a lack of understanding as to how the steroid estrogens and other EDCs are removed through various wastewater treatment processes. To ensure that future policy decisions are well founded, the Environment Agency (EA) and Department for Environment Food and Rural Affairs (Defra) have instigated a Demonstration Programme, which involves collecting baseline data at 17 STWs across the UK and investment to achieve EDC reduction at 2 full-scale STWs. This paper focuses on the baseline data element of the Demonstration Programme. Given the complexity of the programme, and the technical issues to be resolved it was seen as beneficial to trial the protocol at one or two sites to inform the remainder of the Demonstration Programme. Having a strong analytical capability, Anglian Water Services (AWS) has agreed to take this leading role. [ABSTRACT FROM AUTHOR]

The performance in the removal of estrogenicity from wastewater was studied in three wastewater treatment plants (WWTPs). Different treatment processes were evaluated: stabilization ponds and trickling filter. Sampling was performed from the input to the output of the treatment systems. The total estrogenic activity was determined with MCF-7-derived cell lines which express the endogenous estrogen receptor α. The two wastewater stabilization ponds with long retention time had high removal of estrogenicity (90% to 95%). Trickling filters despite being effective at removing organic load were less effective in removing estrogenicity (42%), and post tertiary ponds enhanced estrogenicity removal. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a new configuration for a compact on-site treatment system, which could become an attractive alternative, from technical, economic, social and environmental viewpoints, to the technologies that are currently employed. The treatment unit consists of a cylindrical tank, where haft of the volume is used as a modified septic tank and the other half is divided between an anaerobic hybrid reactor and a trickling filter. An intermittent feeding system was used, with minimum, mean and maximum flowrate settings (Qmin = 0.251.s-1 Qmean = 0.50 l.s-1 and Qmax = 1.00 l.s-1), to reflect the actual operating conditions of a compact on-site treatment system serving a typical dwelling. An average 24-hour hydraulic detention time was used, corresponding to a flowrate of 750 l.d-1. High removal efficiencies and low concentrations of COD, BOD and TSS in the final effluent were achieved, even when the unit was exposed to hydraulic loading peaks during feeding periods at maximum flowrate. [ABSTRACT FROM AUTHOR]

The Environment Agency have proposed that daily flow volume discharged from small wastewater treatment works should be capable of being measured to an accuracy of ±8%, where the daily totalised flow volume is estimated to be greater than 5m³. It is estimated that every water company in the UK has several hundred small wastewater treatment works that will be required to be equipped with the capability of measuring the released daily totalised flow volume for specified periods. This paper investigates the feasibility of modifying existing dosing syphons, which are present within many of these works, to operate as flow measuring devices. Laboratory testing of a full-scale syphon demonstrated that by the addition of two water level detectors and a data logger to monitor the filling part of the syphon cycle, it is possible to accurately calculate the daily totalised flow volume within the Environment Agency's proposed performance criteria. [ABSTRACT FROM AUTHOR]

The treatment of domestic sewage at low temperature was studied in a two-anaerobic-step system followed by an aerobic step, consisting of an anaerobic filter (AF) + an anaerobic hybrid (AH) + polyurethane-foam trickling filter (PTF). The AF+AH system was operated at a hydraulic retention time (HRT) of 3+6 h at a controlled temperature of 13°C, while the PTF was operated without wastewater recirculation at different hydraulic loading rates (HLR) of 41, 15.4 and 2.6 m³/m²/d at ambient temperature (ca. 15-18°C). The AF reactor removed the major part of the total and suspended COD, viz. 46 and 58% respectively. The AH reactor with granular sludge was efficient in the removal and conversion of the anaerobically biodegradable COD. The AF+AH system removed 63% of total COD and converted 46% of the influent total COD to methane. At a HLR of 41 m³/m²/d, the COD removal was limited in the PTF, while at HLR of 15.4 and 2.6 m³/m²/d, a high total COD removal of 54-57% was achieved without a significant difference between the two HLRs. The PTF was mainly efficient in the removal of particles (suspended and colloidal COD removal were 75-90% and 75-83% respectively), which were not removed in the anaerobic two-step. The overall total COD removal in the AF+AH+PTF system was 85%. Decreasing the HLR from 15.4 to 2.6 m³/m²/d, only increased the nitrification rate efficiency in the PTF from 22% to 60%. Also, at HLR of 15.4 and 2.6 m³/m²/d, PTF showed a similar removal for E. coli by about 2 log. Therefore, the effluent of AF+AH+PTF system can be utilised for restricted irrigation in order to close water and nutrients cycles. Moreover, such a system represents a high-load and a low-cost technology, which is a suitable solution for developing countries. [ABSTRACT FROM AUTHOR]