Urban Wastewater Reclamation Research Articles

Environmental and economic assessment of urban wastewater reclamation from ultrafiltration membrane-based tertiary treatment: Effect of seasonal dynamic

This study aimed to assess the environmental and economic performance of an ultrafiltration (UF) tertiary treatment of effluent from an urban wastewater treatment facility. Data from a UF demonstration plant composed of commercially available equipment, including industrial hollow-fiber membranes was used to project a full-scale facility. The results from the demonstration plant recommended different ranges of transmembrane fluxes and sparging air demands under summer and winter conditions to prevent excessive fouling. The energy balance of the full-scale facility would be 0.308 ± 0.112 kWh·m−3 in summer and 0.140 ± 0.040 kWh·m−3 in winter, with blowers' being the main consumers (86–93 %). CAPEX accounted for €0.030 ± 0.002·m−3 in summer and €0.027 ± 0.002·m−3 in winter and membrane acquisition represented 66–69 % of the investment cost. Energy expenditure was the major OPEX cost (66–79 %), with a total operating cost of €0.077 ± 0.023·m−3 and €0.042 ± 0.008·m−3 in summer and winter, respectively. The final average value obtained for the TAC was €0.107 m−3 in summer and €0.068 m−3 in winter. The environmental assessment confirmed optimizing energy consumption and membrane requirements as the main factors influencing environmental sustainability. Specifically, summer and winter emissions of 0.079–0.175 and 0.043–0.079 kgCO2eq·m−3 (Global warming potential); 8.1 · 10−4–1.7 · 10−3 and 4.8 · 10−3–8.1 · 10−3 m3·m−3 (water consumption); 0.019–0.041 and 0.010–0.019 kg oileq·m−3 (fossil fuel scarcity); and 1.4 · 10−4–2.9 · 10−4 and 7.7 · 10−4–1.4 · 10−4 kg Cueq·m−3 (mineral resource scarcity) were calculated, respectively. The obtained permeate quality complied with the most stringent Spanish and EU regulations.

PI-based cascade control for Fresnel solar collectors in wastewater reclamation

This work presents a novel demonstration-scale integration of a 36-m2 Fresnel solar collector in urban wastewater reclamation. A prototype plant was designed and installed to study Escherichia coli and total coliforms disinfection in continuous flow mode. The plant modelling was empirically addressed, resulting in different linear first-order models, which were used to design a PI-based cascade control approach for the automatic operation of the photoreactor. Considering EU 2020/741 Regulation, water quality Class D and Class A were achieved when operating the upgraded design of the plant at 50°C (200 L/h) and 60°C (150 L/h), respectively.

Assessment of new immobilized photocatalysts based on Rose Bengal for water and wastewater disinfection

The aim of this study was to evaluate the water disinfection capability of new immobilized photocatalysts based on the organic photosensitizer Rose Bengal (RB) supported on glass wool and with two different photocatalyst load (RB_GW_0.22 and RB_GW_0.02). Tests were carried out under different operating conditions in a solar simulator at 30 W/m2 average UV-A irradiation. Isotonic water (IW) (with 9 g/L NaCl), simulated tap water (STW) and simulated urban wastewater effluent (SUWWE) spiked with Escherichia coli and Enterococcus faecalis (106 CFU/mL initial concentrations) were used as water model microbial strains. The mere effect of only irradiance was also investigated as reference of the photocatalytic performance over both bacteria. Results showed that RB_GW_0.22 presented high inactivation for E. faecalis, reaching 6 Log Reduction Value (LRV) in 2 min in IW and STW at pH 5 and 6 in comparison with only irradiance (60 min). In SUWWE, the effect of RB_GW_0.22 was also better for E. faecalis inactivation (60 min), compared to that produced in E. coli (120 min) and without the presence of the photocatalyst (where total inactivation was not achieved after 120 min of treatment). Ecotoxicity (ISO 11348–3:2007) and phytotoxicity (EN ISO 18763:2020) tests of the treated water were also assessed and results showed any significant effect, concluding that the use of RB_GW_0.22 is a promising solar photocatalytic treatment for urban wastewater reclamation and reuse.

Biochemical Treatment and Utilization of Fecal Wastewater

In order to treat and utilize urban fecal wastewater more effectively, a process for biochemical treatment of fecal wastewater from urban settlements was established in this study. After treating the fecal wastewater collected, solid and liquid organic fertilizers can be obtained. Compared to the commercially available urea, the solid organic fertilizer can increase the yield of okra by 12.89% at podding stage, while the liquid organic fertilizer can prolong the flowering period of Chinese orchid by 3 - 4 days compared to the untreated urine. Gases generated by various processing units are all collected to the biological deodorization system for treatment, which have no significant odor after treating through the system. The water outlet from the water reclamation system meets the national quality standards for urban miscellaneous water under urban wastewater reclamation and reuse.

Low Temperature Start-up of Coating Wastewater Treatment Works

The purpose of this paper was to realize rapid start-up of coating wastewater treatment works under low temperature. Thermal insulation treatment was carried out to the pool wall and pool top of the reactor, heating equipment was arranged to ensure that the reactor can provide appropriate temperature conditions for the inoculated sludge, the amount of influent water was reasonably controlled to ensure that microorganisms have appropriate proportion of nutrient elements, and the effluent water of the reactor was continuously detected and the biophase of the sludge was continuously observed. The practice results showed that the reactor ran stably, and the effluent water met the requirements on quality of washing water and boiler make-up water in Urban Wastewater Reclamation and Reuse Industrial Water Quality (GB/T 19923-2005). The coating wastewater has a complex composition, a high COD content and poor biodegradability (Sun et al., 2009; Zhang and Li, 2009; Dong et al., 2013) as it contains a large amount of residual acrylic resin, amino resin, nitrocellulose film-forming agent, water-soluble dye colorants, brighteners, surfactants and other additives. The present works processed the coating wastewater by adopting a process of coagulation-hydrolytic acidification-contact oxidation-sand filtration-activated carbon adsorption. When the project started, the local maximum temperature was about 0 ˚C and the average temperature was -5 ˚C, which was not suitable for the growth of microorganisms. The present works adopted rock wool covered insulation, electric heating system configuration and other measures to ensure successful start-up of the hydrolytic acidification pond and contact oxidation pond.

Fate of NDMA precursors through an MBR-NF pilot plant for urban wastewater reclamation and the effect of changing aeration conditions

The removal of N-nitrosodimethylamine (NDMA) formation potential through a membrane bioreactor (MBR) coupled to a nanofiltration (NF) pilot plant that treats urban wastewater is investigated. The results are compared to the fate of the individual NDMA precursors detected: azithromycin, citalopram, erythromycin, clarithromycin, ranitidine, venlafaxine and its metabolite o-desmethylvenlafaxine. Specifically, the effect of dissolved oxygen in the aerobic chamber of the MBR pilot plant on the removal of NDMA formation potential (FP) and individual precursors is studied.During normal aerobic operation, implying a fully nitrifying system, the MBR was able to reduce NDMA precursors above 94%, however this removal percentage was reduced to values as low as 72% when changing the conditions to minimize nitrification. Removal decreased also for azithromycin (68–59%), citalopram (31–17%), venlafaxine (35–15%) and erythromycin (61–16%) on average during nitrifying versus non-nitrifying conditions. The removal of clarithromycin, o-desmethylvenlafaxine and ranitidine could not be correlated with the nitrification inhibition, as it varied greatly during the experiment time. The MBR pilot plant is coupled to a nanofiltration (NF) system and the results on the rejection of both, NDMA FP and individual precursors, through this system was above 90%.Finally, results obtained for the MBR pilot plant are compared to the percentage of removal by a conventional full scale biological wastewater treatment plant (WWTP) fed with the same influent. During aerobic operation, the removal of NDMA FP by the MBR pilot plant was similar to the full scale WWTP.

A case study of urban wastewater reclamation in Spain: comparison of water quality produced by using alternative processes and related costs

In Spain, and particularly in the Valencia Region, the scarcity of water resources means that water resource exploitation must be optimized. In this light, reusing the large amounts of treated wastewater is a top priority, especially in agriculture, urban use and the irrigation of golf courses. Rincón de León wastewater treatment plant–water reclamation plant (Alicante, Spain) supplies reclaimed flow to a number of users according to the guidelines stated in the Royal Decree 1620/2007. Reclamation treatment includes: coagulation + flocculation + filtration (sand bed), ultrafiltration, ultraviolet disinfection and desalination (reverse osmosis). By combining these processes, three tertiary treatment alternatives were configured, and for each of them the quality of effluents, treatment costs, energy consumption and the uses of treated water were analysed. The results show that the quality of the water treated using the three alternatives is suitable for different uses. Moreover, the costs resulting from the tertiary treatment processes, their energy consumption and the final price of the treated water paid by farmers have been obtained.

Optimization of an integrated electrodisinfection/electrocoagulation process with Al bipolar electrodes for urban wastewater reclamation

In this work, a novel integrated electrochemical process for urban wastewater regeneration is described. The electrochemical cell consists in a Boron Doped Diamond (BDD) or a Dimensionally Stable Anode (DSA) as anode, a Stainless Steel (SS) as cathode and a perforated aluminum plate, which behaves as bipolar electrode, between anode and cathode. Thus, in this cell, it is possible to carry out, at the same time, two different electrochemical processes: electrodisinfection (ED) and electrocoagulation (EC). The treatment of urban wastewater with different anodes and different operating conditions is studied. First of all, in order to check the process performance, experiments with synthetic wastewaters were carried out, showing that it is possible to achieve a 100% of turbidity removal by the electrodissolution of the bipolar electrode. Next, the effect of the current density and the anode material are studied during the ED–EC process of actual effluents. Results show that it is possible to remove Escherichia coli and turbidity simultaneously of an actual effluent from a WasteWater Treatment Facility (WWTF). The use of BDD anodes allows to remove the E. coli completely at an applied electric charge of 0.0077 A h dm−3 when working with a current density of 6.65 A m−2. On the other hand, with DSA anodes, the current density necessary to achieve the total removal of E. coli is higher (11.12 A m−2) than that required with BDD anodes. Finally, the influence of cell flow path and flow rate have been studied. Results show that the performance of the process strongly depends on the characteristics of the initial effluent (E. coli concentration and Cl−/NH4+ initial ratio) and that a cell configuration cathode (inlet)–anode (outlet) and a higher flow rate enhance the removal of the turbidity from the treated effluent.

城市污水再生利用系统分析及模拟预测

本文利用系统分析法全面地分析了城市污水再生利用系统的组成、结构和影响因素，在此基础上建立了城市污水再生利用系统SD模型，通过不同回用方案对未来十年我国城市污水再生利用前景进行了方案的模拟与预测。结果表明：在污水二级处理年增长率为3.5%，污水回用增长率为2%的情况下，2022年污水二级处理率将达到91.2%，污水回用率为25.4%，COD减排削减到2445.8亿t，均达到了国家规划目标要求，但是回用工程每年的投资至少占GDP的0.04%以上。 In order to coordinate into conventional water resources system, the wastewater reuse system should be technologically designed to maximize the profit of operation. The composition, structure and influencing factors of urban wastewater reclamation and reuse system were systematically analyzed in this study. A system dynamic (SD) model for urban wastewater reclamation and reuse planning was established to simulate the dynamic development of solutions and their influence on economic for the next decade. The annual growth rates of secondary treatment and wastewater reuse were set as 3.5% and 2%, respectively. The secondary treatment rate, wastewater reuse rate, and COD reduction would be up to 91.2%, 25.4%, and 244.58 billion tons in 2022, respectively. With the investment of wastewater reuse larger than 0.04% of annual GDP, all of result could meet the national plans.

Environmental optimization of continuous flow ozonation for urban wastewater reclamation

Wastewater samples from the secondary clarifier of two treatment plants were spiked in the microgram-to-tens-of-microgram per liter range with diuron (herbicide), ibuprofen and diclofenac (anti-inflammatory drugs), sulfamethoxazole and erythromycin (antibiotics), bezafibrate and gemfibrozil (lipid regulators), atenolol (β-blocker), carbamazepine (anti-epileptic), hydrochlorothiazide (diuretic), caffeine (stimulant) and N-acetyl-4-amino-antipiryne, a metabolite of the antipyretic drug dypirone. They were subsequently ozonated in continuous flow using 1.2L lab-scale bubble columns. The concentration of all spiking compounds was monitored in the outlet stream. The effects of varying ozone input, expressed as energy per unit volume, and water flow rate, and of using single or double column were studied in relation to the efficiency of ozone usage and the ratio of pollutant depletion. The ozone dosage required to treat both wastewaters with pollutant depletion of >90% was in the 5.5–8.5mg/L range with ozone efficiencies greater than 80% depending on the type of wastewater and the operating conditions. This represented 100–200mol of ozone transferred per mole of pollutant removed. Direct and indirect environmental impacts of ozonation were assessed according to Life Cycle Assessment, a technique that helped identify the most effective treatments in terms of potential toxicity reduction, as well as of toxicity reduction per unit mass of greenhouse-gas emissions, which were used as an indicator of environmental efficiency. A trade-off between environmental effectiveness (toxicity reduction) and greenhouse-gas emissions was observed since maximizing toxicity removal led to higher greenhouse-gas emissions, due to the latter's relatively high ozone requirements. Also, there is an environmental trade-off between effectiveness and efficiency. Our results indicate that an efficient use of ozone was not compatible with a full pollutant removal.

Suitability Evaluation for the Construction of Decentralized Wastewater Reclamation Facilities in Beijing

Abstract: Due to water shortages, many districts and cities have started reusing wastewater as an inexpensive supplemental source of water. This study was conducted to evaluate the suitability of various sites for construction of decentralized wastewater reclamation facilities, to identify suitable conditions for reclaimed water reuse in various industries, and to provide helpful information for the formulation or revision of urban wastewater reclamation policies. To accomplish this, the factors influencing the construction of wastewater reclamation facilities were analyzed taking Beijing as an example. In addition, the suitability of wastewater reclamation by water consumers from government institutes, colleges and hotels in Beijing was evaluated after consideration of the water consumption of several consumers in each of these industries. The results indicate that most government institutes and one- and two—star hotels are not suitable, while most hotels of three—star or higher level and most colleges a...

Thermodynamic analysis of an urban water system with reclaimed water as supplemental water resource

The natural water system maintains its dynamic equilibrium through a hydrological cycle that involves a series of natural processes. Such a natural water cycle has been much disturbed by human activities in the process of water use. An urban water system was thus modeled in this paper as a series of artificial water cycles overlaid upon the natural water cycle. The system was thermodynamically analyzed by calculating the entropy budget as ΔS = ΔiS + ΔeS where ΔiS and ΔeS are the entropy increases due to natural and artificial contributions, respectively. The natural water cycle free from human disturbance should possess the nature of self maintenance of water and materials balance and could be assumed as a pseudo-reversible process with ΔiS → 0. ΔeS was then supposed as to be contributed by artificial disturbances on water quantity such as by water withdrawal, and on water quality such as by pollutant discharge. A series of models were developed for calculating ΔeS. As a result of scenario analysis of urban water system in Xi'an, a metropolitan in northwestern China, using these models, it was indicated that under the current condition of water supply and wastewater treatment, if 20% of the treated wastewater could be reused, ΔeS would be decreased by 15.22% from the current level, while if the percent of treated wastewater reuse could be increased to 40%, ΔeS would be decreased by 29.93%. Thermodynamic analysis thus provided a tool for quantitative evaluation of the effect of urban wastewater reclamation and reuse.

Life Cycle Assessment of Urban Wastewater Reclamation and Reuse Alternatives

Summary Continuous population growth is causing increased water contamination. Uneven distribution of water resources and periodic droughts have forced governments to seek new water sources: reclaimed and desalinated water. Wastewater recovery is a tool for better management of the water resources that are diverted from the natural water cycle to the anthropic one. The main objective of this work is to assess the stages of operation of a Spanish Mediterranean wastewater treatment plant to identify the stages with the highest environmental impact, to establish the environmental loads associated with wastewater reuse, and to evaluate alternative final destinations for wastewater. Tertiary treatment does not represent a significant increment in the impact of the total treatment at the plant. The impact of reclaiming 1 cubic meter (m3) of wastewater represents 0.16 kilograms of carbon dioxide per cubic meter (kg CO2/m3), compared to 0.83 kg CO2/m3 associated with basic wastewater treatment (primary, secondary, and sludge treatment). From a comparison of the alternatives for wastewater final destination, we observe that replacing potable water means a freshwater savings of 1.1 m3, whereas replacing desalinated water means important energy savings, reflected in all of the indicators. To ensure the availability of potable water to all of the population—especially in areas where water is scarce—governments should promote reusing wastewater under safe conditions as much as possible.

Wastewater mineralization using advanced oxidation process

Water scarcity and environmental considerations are leading to the search for alternatives for industrial and urban wastewater reclamation. The objective of this research study was to examine the potential of recycling wastewater as an alternative or complementary technique for biological treatment. The degradation of organic matter from strained sewage and secondary treated sewage was studied using the advanced oxidation process (AOP) with hydrogen peroxide as an oxidant and iron oxide-based nanocatalysts. This process may be used when contaminants are resistant or toxic to conventional biological treatments. It also may be used as a complementary technique for polishing treated water. AOP, which involves the in situ generation of extremely strong oxidants such as hydroxyl radicals in aqueous solution, has recently appeared as a remarkable technique for accelerating the oxidation and degradation of a broad range of organic matter in wastewater. The final products of this process are carbon dioxide, water...

Microfiltration-membrane-coupled bioreactor for urban wastewater reclamation

A microfiltration-membrane-coupled bioreactor (MMB) on pilot scale was operated for 135 days to investigate its technical feasibility in urban wastewater reclamation. Different operation parameters such as sludge retention time from 5 to 30 days, hydraulic retention time from 3.75 to 7.5 h, and membrane flux from 50 to 100 L.m −2.h −1, were tested. The highest sludge concentration attained was 15.1 g.L −1 (as suspended solids, SS) and 8.9 g.L −1 (as volatile suspended solids, VSS); the VSS to SS ratio of MMB sludge was 0.55 on average. The ratio of sludge VSS to sludge COD was found to be 1.45. The mass loading rates of MMB were close to those of conventional activated sludge process (CASP) but the volumetric loading rates, two to four times those a CASP. Up to 95% of COD, 97.7% of ammonia nitrogen and 100% of suspended solids were removed on average. Further analysis indicated that the bioreactor was responsible for 87% of the total COD removal and only 8% were attributed to the membrane separation. The reclaimed water could be reused either directly or indirectly for municipal or industrial purposes.

Wastewater reclamation and reuse in Japan: overview and implementation examples

To alleviate potentially catastrophic water supply and wastewater disposal problems as well as expand dependable water supply infrastructure, Japan has launched comprehensive urban wastewater reclamation and reuse projects since 1968. In this paper, the status of national policies on wastewater treatment, wastewater reuse characteristics, and some wastewater reuse experiences are presented. Two implementation examples in Tokyo and Fukuoka are discussed in detail, with special reference to application for toilet-flushing in high-rise business buildings and stream restoration and flow augmentation. It was found that the key to the success of wastewater reclamation and reuse is the quality of reclaimed water; public acceptance is closely associated with water quality and water supply dependability.

Wastewater reclamation and reuse in Japan: Overview and implementation examples

To alleviate potentially catastrophic water supply and wastewater disposal problems as well as expand dependable water supply infrastructure, Japan has launched comprehensive urban wastewater reclamation and reuse projects since 1968. In this paper, the status of national policies on wastewater treatment, wastewater reuse characteristics, and some wastewater reuse experiences are presented. Two implementation examples in Tokyo and Fukuoka are discussed in detail, with special reference to application for toilet-flushing in high-rise business buildings and stream restoration and flow augmentation. It was found that the key to the success of wastewater reclamation and reuse is the quality of reclaimed water; public acceptance is closely associated with water quality and water supply dependability.