Conventional Treatment Facilities Research Articles

Performance assessment of photo-controlled catalytic and moving biocarrier-based hybrid systems for the treatment of pharmaceuticals from municipal and industrial wastewater: Insights into influencing factors and degradation mechanisms

Diclofenac (DCF) and tetracycline (TC) are globally found in wastewater due to their excessive use and recalcitrant properties. The inefficacy of conventional treatment facilities has shifted the focus toward implementing advanced oxidation processes. This study used the S-C3N4/ZnO-chitosan (named SCZ-CH) hydrogels as a photocatalyst to remove the DCF and TC with ∼92 % and ∼93 % degradation efficiency, respectively, in 300 min. The SCZ-CH hydrogels offered enhanced mineralization efficiency and reusability (11 cycles). The improved performance of SCZ-CH hydrogels was mostly due to the existence of crystalline structures, oxygen concentrations, and surface roughness. The scavenging study identified the superoxide as the driving radical, which primarily transformed the targeted pharmaceuticals into their intermediates. The SCZ-CH hydrogels were successfully applied to treat the synthetic, municipal, and industrial wastewater using a continuous photocatalytic system. Further, a modified moving bed biofilm reactor was integrated with the photocatalytic system to remove the biodegradable compounds, which significantly enhanced the pharmaceuticals removal (∼96 % for municipal wastewater and ∼99 % for industrial wastewater). The SCZ-CH hydrogels acquired up to 95 % degradation efficiencies for the ternary mixture of DCF and TC with ciprofloxacin. The removal of pharmaceuticals or other micropollutants at trace levels from municipal and industrial wastewater, the ease with which the catalyst can be separated from the aqueous medium due to its hydrogel-like structure, and the high removal rate of the hybrid photocatalytic system, which requires less space and time, are all noteworthy scientific contributions of this study.

Exploring the benefits of utilizing small modular device for sustainable and flexible shale gas water management

Growing shale gas extraction in recent years has triggered wide discussions on the associated freshwater requirement and wastewater management. Many optimization approaches have been developed for shale gas water management; however, most of the studies assumed permanent utilization of wastewater treatment facilities with fixed capacities. Considering the rapidly declining characteristics of shale gas wastewater production, these treatment facilities could remain largely underutilized after the first few months/years of production, making them less economically attractive. To maximize the capacity utilization of treatment facilities and further improve the economic performance of shale gas development, this study develops a systematic optimization framework, where the capacity strategy of conventional treatment facilities and utilization of the recent concept of modular manufacturing are both considered for flexible shale gas water management. The proposed mixed-integer linear programming (MILP) model simultaneously optimizes the design and planning of integrated shale gas and water supply chain, with a focus on capacity planning for both large-scale conventional treatment facilities and small-scale modular devices. A series of Marcellus-based case studies are performed to illustrate the applicability of the proposed model and provide general insights into the trade-offs between the multiple types of treatment facilities. The optimization results reveal that the combinatorial utilization of conventional facilities and modular devices for wastewater treatment (66% by conventional facilities and 34% by modular devices) brings 9.3% more reused water for other well development and 6.2% savings in water-related costs, compared to flexible management of only conventional facilities. This work suggests that taking modular device as auxiliary equipment for shale gas water management is most beneficial to increase the capacity utilization of treatment facilities and achieve a more economic and sustainable shale gas production system.

Impacts of seasonality and operating conditions on algal-dual osmosis membrane system for potable water reuse: Part 2

This study investigated the impact of seasonal variation and operating conditions on recovery of potable quality water from municipal wastewater effluent using an integrated algal treatment process with a dual forward osmosis (FO)-reverse osmosis (RO) membrane system. Pilot study of the algal process treating primary effluent validated the technical viability and seasonal performance during warm weather (May to October, 25–55 °C) using an extremophilic algal strain Galdieria sulphuraria, and during cold weather (November to April, 4–17 °C) using polyculture strains of algae and bacteria. Algal effluents from both seasons were used as the feed solution for the laboratory FO-RO study. In addition, pilot-scale FO-RO experiments were conducted to compare the system performance during treatment of algal effluent and secondary effluent from the conventional treatment facility. At 90% water recovery, the FO-RO achieved over 90% overall rejection of major ions and organic matter using the bench-scale system and over 99% rejection of all contaminants in pilot-scale studies. Detailed water quality analysis indicated that the product water from the integrated system met both the primary and secondary drinking water standards. This study demonstrated that the FO-RO system can be engineered as a viable alternative to treat algal effluent and secondary effluent for potable water reuse independent of seasonal variations and operating conditions.

Bioelectrochemical system as an innovative technology for treatment of produced water from oil and gas industry: A review

Disposal of the high volume of produced water (PW) is a big challenge to the oil and gas industry. High cost of conventional treatment facilities, increasing energy prices and environmental concern had focused governments and the industry itself on more efficient treatment methods. Bioelectrochemical system (BES) has attracted the attention of researchers because it represents a sustainable way to treat wastewater. This is the first review that summarizes the progress done in PW-fed BESs with a critical analysis of the parameters that influence their performances. Inoculum, temperature, hydraulic retention time, external resistance, and the use of real or synthetic produced water were found to be deeply related to the performance of BES. Microbial fuel cells are the most analyzed BES in this field followed by different types of microbial desalination cells. High concentration of sulfates in PW suggests that most of hydrocarbons are removed mainly by using sulfates as terminal electron acceptor (TEA), but other TEAs such as nitrate or metals can also be employed. The use of real PW as feed in experiments is highly recommended because biofilms when using synthetic PW are not the same. This review is believed to be helpful in guiding the research directions on the use of BES for PW treatment, and to speed up the practical application of BES technology in oil and gas industry.

한강수계 비점오염원 저감시설의 생애주기비용 평가

환경부는 비점오염원 관리를 위해 시범사업으로 12개의 비점오염 저감시설을 경안천 유역에 설치하였으며, 2006년부터 모니터링이 시작되었다. 본 연구는 비점오염 저감시설의 오염부하량, 저감효율, 유지관리 활동 등의 장기간 수행된 모니터링 결과를 바탕으로 각 시설의 경제성을 평가하기 위해 수행되었으며, 생애주기비용(Lifecycle cost, LCC)을 분석하였다. 비점오염 저감시설의 유지관리는 시설경관을 향상시키기 위한 심미적 관리가 중점적으로 수행된 것으로 나타났으며, 저류형 시설(Retention Pond, RP)이 년간 8,483$, 침투형 시설(Infiltration System, IS)이 8,888$로 대부분 비슷한 비용이 발생한 것으로 분석되었다. LCC는 인공습지(Constructed Wetland, CW)가 가장 높은 것($418,324)으로 나타났으며, 반면에 식생형 시설(Vegetated System, VS)이 가장 낮은 것($210,418)으로 분석되었다. 본 연구에서 조사된 비점오염 저감시설의 LCC와 하수처리장 등 수질처리시설의 LCC를 비교한 결과 비점오염 저감시설이 낮은 것으로 나타났다. 한편, 처리용량 대비 생애주기비용이 높아질수록 TSS와 TN의 저감효율은 높아지는 것으로 나타났다. 이러한 연구결과는 비용효율적인 비점오염 저감시설을 설계하는데 유용하게 활용될 것으로 기대되며, 향후 LCC 모델의 기초자료에도 활용될 수 있을 것으로 판단된다. Diffuse pollution management in Korea initiated by the Ministry of Environment (MOE) resulted to the construction of pilot facilities termed Best Management Practices (BMPs). Twelve BMPs installed for the diffuse pollution management in the Kyung-An Stream were monitored since 2006. Data on the mass loading, removal efficiency, maintenance activities, etc. were gathered and utilized to conduct the evaluation of long-term performance of BMPs. The financial data such as actual construction, design and maintenance cost were also collected to evaluate the lifecycle cost (LCC) of BMPs. In this study, most of the maintenance activity was focused in the aesthetic maintenance that resulted to the annual maintenance cost of the four BMP types was closely similar ranging from 8,483 $/yr for retention pond to 8,888 $/yr infiltration system. The highest LCC were observed in constructed wetland ($418,324) while vegetated system had the lowest LCC ($210,418). LCC of BMPs was not so high as compared with the conventional treatment facility and sewage treatment plant. On the other hand, the relationship of removal efficiency on unit cost for TSS and TN was significant. This study will be used to design the cost effective BMP for diffuse pollution management and become models for LCC analysis.

Evaluation of Horizontal–Vertical Subsurface Hybrid Constructed Wetlands for Tertiary Treatment of Conventional Treatment Facilities Effluents in Developing Countries

In this study, four large pilot-scale horizontal–vertical hybrid constructed wetlands (CWs) were constructed for the tertiary treatment of effluent of North Wastewater Treatment Plant in Isfahan, Iran. The plant effluent did not meet the regulation limits of wastewater reuse for various applications (e.g., irrigation of food and non-food crops, forests and green areas, groundwater recharge, and urban reuse applications). So the hybrid CW system was set up to provide a suitable effluent for this purpose. Each hybrid unit consisted of a 100-m2 horizontal flow (HF) and a 32-m2 vertical flow (VF) subsurface CW operating in series. Three emergent plants consisting of Phragmites australis, Typha latifolia, and Arundo donax were planted in the CWs and one unit left unplanted. The filling material was fine grain from 3–7 mm. The average organic load and the average hydraulic loading rate (HLR) of the system were 15 g biochemical oxygen demand (BOD5) m−1 day−1 and 5.3 cm day−1, respectively. The k-C* first-order model constant was computed for seven physical, chemical, and microbiological parameters—BOD5, chemical oxygen demand (COD), total suspended solids (TSS), NO3-N, NH4-N, total phosphorus (TP), and fecal coliforms—based on the influent/effluent concentration data for estimation of required surface area of full-scale CWs in the future. The results of 12-month sampling showed that the hybrid HF-VF CWs are highly efficient in removing of the BOD5 (85 % medium), COD (80 % medium), TSS (79 % medium), NH4-N (78 % medium), TP (74 % medium), and fecal coliforms (99 % medium). Also, there were no significant differences between various planted hybrid CWs in removal efficiency and first-order model constant for BOD5, COD, TSS, and coliforms, nor were there significant differences between planted and unplanted CWs for these parameters. But, for nutrients, the removal efficiencies of planted CWs were higher than those of control CW during the operation time. Among the CWs, the Phragmites showed the best efficiency for removal of nutrients followed by Arundo. It was observed that the removal efficiencies in HFCWs were higher than those in VFCWs due to longer hydraulic retention time (HRT), but for coliform removal, the VFCWs showed a higher efficiency. The effluent quality met the requirements for its reuse in various applications, but bacterial contents were equal to levels that permit the reuse of effluent in the non-food crop, forest and other green area irrigation, groundwater recharge, and some urban applications with restricted public exposure. The results of this pilot-scale research study showed that the performance of a single HFCW was probably not sufficient to achieve a suitable water quality for reuse of effluents and the hybrid CWs are more efficient and feasible systems for this purpose.

Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry

Since nanoparticles are considered emerging contaminants in water, there is a pressing need to ensure their removal. Specifically, recent studies have found titanium dioxide nanoparticles (TiO2) to potentially cause adverse environmental and health effects. Typical treatment plants have three stages of prefiltration treatment in which particles may be removed: coagulation, flocculation, and sedimentation. Scaled-down jar tests, with constant dosage of aluminum sulfate as the coagulant, were utilized to investigate the efficacy of conventional treatment facility to remove nanoparticles and the fundamental mechanisms involved under ideal and environmentally relevant conditions. Results showed that removal by sedimentation was the most efficient in the presence of divalent cations and in the absence of natural organic matter (NOM) and synthetic organic coating on the nanoparticles, achieving >1 log removal. With the addition of a synthetic organic coating on the nanoparticles and NOM, removal decreased to ∼80%. Despite the high dosage of coagulant used, without pH modification (typical of practical treatment), under realistic water chemistries there is a possibility for significant release, and specifically ∼5 ppm of particles smaller than 450 nm were observed after sedimentation, which raises concern regarding the ability for these engineered treatment facilities to adequately remove these nanoparticles that are increasing in production and use.

Comparison of drinking water pollutant removal using a nanofiltration pilot plant powered by renewable energy and a conventional treatment facility

In this paper, drinking water pollutant removal between a conventional drinking water treatment and a nanofiltration (NF) pilot plant powered by renewable energy is compared. This kind of plant can be very useful for isolated locations with water quality problems. Energy consumption and related CO2 emissions and the occurrence of synthetic organic compounds in drinking water sources are important environmental and public health issues. NF membranes were used to improve drinking water quality from a holistic point of view. Compared to conventional drinking water treatment, membranes efficiently removed color and turbidity (100%), DOC (93%), ions (97%), and metals and metalloids (ranging from 80% to 100%), but not boron (17%) or pharmaceuticals (Ph's) (varied from 15% to 100%, but still always above conventional treatment). Moreover, NF membranes removed 53% of the trihalomethanes (THMs) present in conventionally treated water. Analyses of 93 persistent organic compounds (VOCs, BTEXs, PAHs, DEs, pesticides…) were carried out, but none of the compounds were detected in the three types of water analyzed (reservoir, conventionally treatment and NF permeate). Reservoir water has a strong hydrophilic composition due to protein-like substances that can promote biofouling. NF membranes effectively removed the hydrophobic fraction (66%).

Alcohol y exclusión social

Pathological alcohol consumption is in many occasions on the basis of social exclusion, which is not addressed by most of the conventional treatment facilities. Sometimes clients do not reach services, while in other occasions they’re not interested in the abstinence based approach. This work makes different proposals aiming at making those groups of people more visible to society. It also proposes the use of social mediators to work with reach out strategies in order to approach those clients. Specific centers which allow for medium and long stay should be created. These includes halfway houses and therapeutic apartments where clients can be approached on a motivational basis and with different harm reduction strategies. The second part of the article addresses the connections between alcohol, immigration and social exclusion. Immigrants are usually more vulnerable to alcohol, and alcohol itself becomes a pathway to social exclusion. Different studies reviewed show the links between alcohol and immigration, but they also show how drinking patterns tend to conform to those of the new country when immigrants reach social stability.

Application of immersed ultrafiltration membranes for organic removal and disinfection by-product reduction

Natural organic matter (NOM) present in raw water can not only impart color to water, but can also cause health risks associated with disinfection by-products (DBP). The most common DBPs found in drinking water are trihalomethanes (THMs) and haloacetic acids (HAAs), which are formed when NOM reacts with chlorine or chlorine based disinfectants. In order to prevent the formation of DBP's, the US EPA has introduced a two stage Disinfectants-Disinfection Byproduct Rule (D/DBPR). Stage 1, finalized in November of 1998, established the maximum contaminant level (MCL) at 0.080 mg/L for total trihalomethanes (TTHMs) and 0.060 mg/L for five haloacetic acids (HAA5). This will be followed by Stage 2 (Final Rule due in 2002) of the D/DBPR, which may set lower contaminant levels at 0.040 mg/L and 0.030 mg/L for TTHM's and HAA5, respectively. Enhanced coagulation has been identified as the best available technology for meeting the requirements of the D/DBP Stage 1 Rule for Total Organic Carbon (TOC) reduction and the removal of disinfection byproduct precursors. With enhanced coagulation, NOM, color and TOC reduction is achieved using a higher coagulant dosage than would be utilized for turbidity removal. The pH of the raw water is also commonly optimized to maximize process efficiency. The application of immersed ultrafiltration membranes using enhanced coagulation has been successfully applied for disinfection byproduct precursor (DBP), color and TOC removal for drinking water applications. With this process, a single tank coagulation-ultrafiltration process replaces the coagulation-flocculation-sedimentation-filtration stages of a conventional treatment plant. Enhanced coagulation ultrafiltration has three stages: 1) rapid mix, 2) coagulation/adsorption of NOM, and 3) ultrafiltration. A high solids concentration is maintained in the membrane tank to promote the adsorption of organics onto the small settling flocs. Subsequently, the barrier characteristics of the ultrafilter are used to separate flocculated particles, precipitates, and colloidal particles. Powdered activated carbon (PAC) can also be used in combination with enhanced coagulation, or alone to reduce disinfectant byproduct precursors by addition to the rapid mix stage upstream of the ultrafiltration membranes. Compared to conventional treatment, this novel method of water treatment results in higher color and TOC removal and requires less coagulant and PAC. The use of lower chemical dosage results in significantly less treatment residuals and reduced disposal costs. The system also has a small footprint since it is designed with a shorter hydraulic retention time as it is only necessary to form a floc that exceeds the membrane pore size. This paper presents the application of immersed ultrafiltration membranes using enhanced coagulation and PAC processes for color and TOC removal as well as the reduction of DBP precursors. It also presents pilot data on a number of applications where the process is being effectively used and compares it with performance data reported for conventional treatment facilities using enhanced coagulation.

USING WATER HYACINTH TO TREAT MUNICIPAL WASTEWATER IN THE DESERT SOUTHWEST1

ABSTRACT: Water hyacinth (Eichhornia crassipes L.) has shown to be effective in the treatment of municipal wastewater in a pilot study begun in January 1989 by the Pima County Wastewater Management Department and researchers associated with The University of Arizona's Office of Arid Lands Studies in the Sonoran Desert near Tucson. The influent pumped into the pilot facility's six raceways (ponds) typically has been treated secondary effluent diverted from a conventional treatment facility, although primary effluent from the same facility also has been treated. The Secondary Influent Treatment System has met the Arizona Department of Environmental Quality (ADEQ) tertiary standard for BOD5 and TSS of 10 mg/l for every month of its operation since March 1990; the Primary Influent Treatment System met the ADEQ secondary standard for BOD5 and TSS of 30 mg/1 for most of the 10 months it was in operation.

The A–B Process: A Novel two Stage Wastewater Treatment System

New acts on wastewater disposal demand for higher process stability and effluent quality. The A-B process, a novel two step treatment system, meets these requirements in a cost effective way. Five full-scale plants have been put in operation over the last two years. The objective of this paper is to give an outline of the features of the A-B system in the context of the results of these full-scale plants. In spite of the extreme high load, the A-stage can be operated at a high reduction rate and is stable. Variations in the organic load and pH- and toxic shocks are leveled out and a constant, mainly soluble effluent is supplied. This implicates a low sludge production in the B-stage. As a consequence higher overall reduction rates are obtained as compared to conventional processes at the same sludge load. Very low and stable final effluent concentrations are observed in all full-scale plants. Of special interest are the possibilities of upgrading existing conventional treatment facilities, at minor costs, by incorporating the A-B technology. The A-B process therefore can be considered as a very promising, cost effective alternative for both existing and new wastewater treatment plants in responding to the increasing effluent demands.