Domestic Wastewater Reclamation Research Articles

Development of a membrane capacitive deionization stack for domestic wastewater reclamation: A pilot-scale feasibility study

This study aims to scale up a membrane capacitive deionization (MCDI) stack for the reuse of domestic wastewater for industry applications. The desalination performance of the pilot-scale MCDI was investigated for the removal of ions from the effluent of a domestic wastewater treatment plant in terms of water quality, ion selectivity, water productivity and fouling/scaling phenomena. The MCDI stack was composed of 40 pairs of 20 cm × 20 cm activated carbon electrodes and operated in a single-pass mode. The MCDI stack achieved good removal efficiency of ions from the wastewater effluent (up to 94% Ca2+ and 84% NO3−). For electrode regeneration, the pump-off operation enabled a much higher water recovery of 75%. In particular, the average conductivity after the MCDI treatment was 103 μS/cm, which meets the standard for industrial reuse. For the electrosorption selectivity of cations, Ca2+ and Mg2+ were favored due to their high charge. Among the anions, NO3− had the highest electrosorption selectivity owing to its hydration ratio. Notably, the water quality of MCDI-treated effluents remained stable during consecutive charging-discharging cycles over 5 months of operation. These results provide essential data to scale up the MCDI stack with application to water reclamation.

Domestic wastewater treatment for single household via novel subsurface wastewater infiltration systems (SWISs) with NiiMi process: Performance and microbial community

Subsurface wastewater infiltration systems (SWISs) were widely used in decentralized domestic wastewater treatment. However, their clogging risk and unstable performance remain pressuring issues. In this study, novel SWISs with NiiMi process have been developed in the treatment of domestic wastewater. Moreover, the impacts of substrates and operating modes on removal performance of SWISs were systemically evaluated. The results indicated that optimal removal performance was achieved in Sandy soil system with intermittent time of 6h and RWD of 1.0. The removal efficiencies of chemical oxygen demand (COD), total phosphorus (TP), and NH4+–N of best-performing Sandy soil system reached 94.81%, 97.25% and 75.02%, respectively. The average removal rete of COD, TP, and NH4+–N of Sandy soil system reached 35.80, 0.74, and 2.79 gm−2d−1, respectively. The effluent of Sandy soil system has satisfied the limits of The Reuse of Urban Recycling Water (GB/T 18921–2002). High-throughput sequencing indicated that the percentage of denitrifiers in Krasnozem system, Brown soil system, and Sandy soil system reached 58.95%, 64.79%, and 25.31%, respectively. Pseudomonas, Anaerolineaceae-uncultured and Bacillus were predominant functional genera in carbon and nitrogen cycling of SWISs. Overall, the Sandy soil system with NiiMi process is feasible for single household in the treatment and reclamation of domestic wastewater.

Green Synthesis of Fe3O4@Carbon Filter Media for Simultaneous Phosphate Recovery and Nitrogen Removal from Domestic Wastewater in Biological Aerated Filters

Domestic wastewater depth processing and reclamation are essential in the alleviation of global water shortage. In this study, an innovative filter media (i.e., Fe3O4@Carbon filter media [FCM]) was...

Correction to: Building a low-cost domestic wastewater reclamation system using local agricultural waste in Kinmen islands, Taiwan

In the original publication of the article, the affiliations of the authors have been mentioned incorrectly. Now the correct affiliations have been provided in this correction.

Investigating the bacterial community and amoebae population in rural domestic wastewater reclamation for irrigation

Reclamation of domestic wastewater for agricultural irrigation is viewed as a sustainable option to create an alternative water source and address water scarcity. Free-living amoebae (FLA), which are amphizoic protozoa, are widely distributed in various environmental sources. The FLA could cause considerable environmental and health risks. However, little information is available on the risk of these protozoa. In this study, we evaluated the feasibility using rural domestic wastewater for agricultural irrigation, and analyzed dynamic changes of the microbial community structure and FLA populations in raw and treated wastewater, as well as the phyllosphere and rhizosphere of lettuce production sites that were irrigated with different water sources. The bacterial community dynamics were analyzed by terminal restriction fragment length polymorphism (T-RFLP). The bacterial community structures in the influent were similar to that in the effluent, while in some cases relative abundances varied significantly. The populations of Acanthamoeba spp. and Hartmannella vermiformis in the anaerobically treated wastewater were significantly higher than in the raw wastewater. The vegetables could harbor diverse amoebae, and the abundances of Acanthamoeba spp. and H. vermiformis in the rhizosphere were significantly higher than in the phyllosphere. Accordingly, our studies show insight into the distribution and dissemination of amoebae in wastewater treatment and irrigation practices.

Building a low-cost domestic wastewater reclamation system using local agricultural waste in Kinmen islands, Taiwan

The ongoing processes of climate change and natural resource exhaustion have an especially great impact on small islands. Kinmen is an archipelago of several islands of approximately 150 km2 in area located off the southeast coast of mainland China. Kinmen does not have an abundance of natural resources, and therefore, its development is restricted by the ecological environment and reflected in cultural fragility. After the end of military administration in 1992, Kinmen transformed into a famous tourist attraction. The rapid development of tourism has attracted a large number of tourists, but also worsens the long-standing scarcity of freshwater resources. As Kinmen is currently aiming to move toward becoming a low-carbon demonstration island, installation of a water reclamation system with a low carbon consumption would be the best choice for the islands. A wastewater reclamation system that considers local conditions and uses local materials to reduce the carbon footprint was therefore proposed in this study. To reduce the carbon footprint, the system uses local agricultural waste, including sorghum stalks and oyster shells, as filter media to construct a water purification system that can purify domestic wastewater by reclamation. The results demonstrated that the reductions in suspended solids, biochemical oxygen demand and NH4-N using this system reached 95.3, 97.0 and 99.3%, respectively, achieving the standards required for tertiary wastewater treatment. In addition, oyster shells after burning absorbed around 50% of the phosphorus in wastewater. The findings demonstrated that this low-carbon water reclamation system can achieve waste reduction, recycling wastewater to a quality suitable for irrigation.

Antiscaling effect of polyaspartic acid and its derivative for RO membranes used for saline wastewater and brackish water desalination

Polyaspartic acid (PASP) and its derivative (PASP-SEA-ASP) were tested as environmentally benign scale inhibitors at lab scale for a polyamide reverse osmosis (RO) membrane in the desalination of a synthetic brackish water containing various scale-forming ions. Their performance was compared with a commercially available RO antiscalant which contains phosphonic acid. The addition of the scaling inhibitors to feedwater led to increase in water recovery and removal efficiency of inorganic matter for the RO unit operated under constant transmembrane pressure, with PASP-SEA-ASP giving greater water recovery (90%) than PASP (87%) and the commercial antiscalant (85%). PASP-SEA-ASP was superior to PASP and the commercial antiscalant in scaling inhibitor/fouling reduction due to the reduced deposition of the scale forming ions on the membrane. Examination of the used membranes with scanning electron microscopy and X-ray diffraction suggested the different effect of the antiscalants was related to the resultant crystalline morphology on the membrane surface. The PASP and its derivative appeared to be more cost effective in maintaining permeate flux and inhibiting the formation of a dense scale layer. The present study demonstrated the great potential of these non-phosphorus containing agents for scale inhibition in domestic and industrial wastewater reclamation and brackish water desalination applications.

Number of residual thermotolerant coliforms on plants and in soil when using reclaimed domestic wastewater for irrigation

The reclamation of domestic wastewater for irrigation is one alternative approach to solve the water scarcity crisis, but it is essential to control the microbiological quality of wastewater used for irrigation. The removal of thermotolerant coliforms, also known as faecal coliforms (FC), from treated domestic wastewater by intermittent media infiltration (IMI) in column was studied. The columns were filled with natural filter media (soil, soil/charcoal and zinc-modified zeolite, Zeo-Zn), and wastewater, IMI-treated wastewater and disinfected wastewater were compared. The numbers of residual FC on Swiss chard (Beta vulgaris) and in agricultural soil were determined over a 4-month period. The column using Zeo-Zn had a higher FC removal efficiency (2.98 log) than columns with other filter media and disinfection (1.87-2.57 log) due to the bactericidal properties of Zn(2+). The treatment of wastewater using Zeo-Zn and disinfection both decreased the accumulation of FC on plants and in soil to approximately 1-20 MPN/g dry matter. IMI-treated wastewater using the column with Zeo-Zn was suitable for unrestricted agricultural use, complied with Mexican regulations (as did disinfected wastewater) and had a low risk of FC contamination of plants and soil.

Integrated coagulation-trickling filter–ultrafiltration processes for domestic wastewater treatment and reclamation

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).

The Coupling Bioreactor for Domestic Wastewater Reclamation and Sludge Reduction

Based on the theory of flow separate and multi-phase reaction principle, the coupling bioreactor for domestic wastewater reclamation and the sludge reduction was developed in this paper. The results showed that the coupling bioreactor kept stable COD removal efficiency above 85% with the COD loading rate increased from 0.49kgCOD/(m3∙d) to 1.93kgCOD/(m3∙d). Moreover, the excellent effluent quality could be obtained under the condition of Micro-aeration+ Anoxic + Aeration, and the total nitrogen(TN) removal of 86.7% was achieved at HRT of 8h and 43% volume ratio of anoxic zone, meanwhile the effluent TN concentration was lower than 15mg/L and a lower sludge production rate was obtained with mean value of 0.068MLSS/kgCOD.

Reclamation of municipal domestic wastewater by aquaponics of tomato plants

In search of low-cost eco-tech for the reclamation of municipal domestic wastewater, tomato plants ( Lycopersicum esculentum) were cultivated on the floating bed of pulp-free coconut fiber over four different concentrations of wastewater (25%, 50%, 75% and 100%) and groundwater as control, in 10 L plastic bucket for two months. The study revealed that PO 4-P was removed by 58.14–74.83% with maximum removal at 50% wastewater. More than 75% removal of NO 3-N was observed in all treatments. Both COD and BOD were reclaimed highest at 100% wastewater by 61.38% and 72.03%, respectively. Ammonium-N concentration was subsided below the toxic level in all the treatments. The population of coliform bacteria ( Escherichia coli) was reduced to 91.10–92.18% with maximum efficiency at 100% wastewater. Growth performance was observed relatively better at 100% wastewater. Crop production as the value addition of this technology was also recorded maximum at 100% wastewater. The bioaccumulation of Cd and Ni in tomato crop was far below the threshold level, but the bioaccumulation of Pb and Cr was above the safe level by 80 times and 660 times, respectively. The aquaponically reclaimed water can be reused in agriculture, aquaculture and industries.

A novel application of automatic vacuum membrane bioreactor in wastewater reclamation

An automatic vacuum membrane bioreactor (AVMBR) equipped with an on-line air–water–chemicals backwashing system was developed for a purpose of the reclamation of domestic wastewater (300–800 mg-COD/L) and traditional Chinese medicine (TCM) wastewater (259–12775 mg-COD/L). The experimental setups were operated in pilot scale at hydraulic retention times (HRTs) of 3, 1 and 0.5 h for domestic wastewater, and at HRTs of 1, 3, 5 and 8 h for TCM wastewater. Experimental results indicated that membrane flux was able to resume as the fouled membrane modules being operated for 150 days were repeatedly subject to an air–water–chemicals backwashing procedure. Compared to a new membrane module, the contaminated membrane fluxes were resumed to 94.7% after the first cleaning, to 82.7% after the second cleaning and to 70.0% after the third cleaning at a vacuum value of 0.02 MPa. To meet reuse standard (effluent COD, less than 30 mg/L), the minimum HRT required by the AVMBR system was 1 h for domestic wastewater reclamation, and 1 h for less than 1000 mg-COD/L, 3.0 h for 1000–3000 mg-COD/L, and 5.0 h for 3000–6000 mg-COD/L TCM wastewater reclamation.However, when the TCM wastewater COD was larger than 6000 mg/L, an 8-h HRT operation of the AVMBR system failed to produce an effluent having a COD concentration less than 30 mg/L. It is concluded that the pilot-scale AVMBR system developed is feasible for the reclamation of domestic wastewater and TCM wastewater with a COD concentration less than 6000 mg/L.

Data envelopment analysis for assessing optimal operation of an immersed membrane bioreactor equipped with a draft tube for domestic wastewater reclamation

Membrane fouling can be minimized by air lifting that plays a key role in cake removal from membrane surface. This study presents the results of tests that were carried out at Kiryat Sde-Boker, Israel, and focuses on the influence of hydrodynamic conditions on membrane fouling in a pilot-scale Immersed Membrane Bio-Reactor (IMBR) using a hollow fiber membrane module of ZW-10 (Zenon Environmental, Canada) under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by a cylindrical draft-tube. The relationship between cross-flow velocity and aeration strength and the influence of the cross-flow on fouling rate (under various hydrodynamic conditions) were investigated using Data Envelopment Analysis (DEA). According to DEA, Technical Efficiency (TE) is defined as the ratio between outputs and inputs of the system [in this case the inputs are: feed temperature and trans-membrane pressure and the outputs are: normalized flux and fouling rate (change of membrane pressure drop with time)]. The developed DEA model for 2# draft tube, Ø = 235 mm allows further modification by changing the inputoutput variables and analyzing a broad pattern of possibilities. Data normalization of the field results and implementing the DEA approach with reference to the technical efficiency is for that reason useful to characterize performance changes for data classification and detecting deviations from expected behavior of the system.

Filtration characteristics of immersed coarse pore filters in an activated sludge system for domestic wastewater reclamation

The filtration characteristics of two different module configurations with coarse pore filter (non-woven fabric) were investigated for sludge floc separation in an activated sludge reactor for domestic wastewater reclamation. A polypropylene non-woven fabric filter (35 g/m2) was used for the two different module configurations, one flat and one tubular type, each with a filtration area of 0.052 m2. The different module types, submerged in the oxic compartment of A/O (anaerobic/oxic) type reactors, were operated simultaneously. The filtration fluxes were gradually increased from 0.5 to 1.2 and 1.73 m/d. The filtration pressures were more stably maintained for the tubular type module than the plate type. The tubular type module installed horizontally with two-side suction showed less filtration pressures than the tubular type module installed vertically with one-side suction. The solid separation was significantly high showing less than 5 mg/L effluent solids. The organic and T-N removal efficiencies were around 95 and 50%, respectively. The 85% removal of T-P was achieved with 20 mg/L injection of PAC (poly-aluminum chloride).

Optimal performance of an immersed membrane bioreactor equipped with a draft tube for domestic wastewater reclamation

One of the options to prevent membrane fouling is to implement air lifting that can improve the cake removal from the membrane surface. This study presents the results of tests that were carried out at the Institutes for Desert Research, Kiryat Sde-Boker, Israel, and focused on the influence of hydrodynamic conditions on fouling in a pilot-scale immersed membrane bioreactor (IMBR) using a hollow fiber membrane module of ZW-10 (Zenon Environmental, Canada) under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by one conical and four cylindrical draft-tubes. The relationship between the crossflow velocity and the aeration intensity, the influence of the crossflow on fouling rate under various hydrodynamic conditions were investigated and optimal operating conditions were obtained. Optimal operating conditions were reached during the long-term experiment period (70 days) for the treatment of domestic wastewater. The system was stable without external chemical cleaning. The results showed that the permeate was of high quality, and the removal of COD and BOD was 94.0% and 98.8%, respectively. The crossflow near the membrane surface reveals a major contribution for minimizing membrane fouling, and could offer guidelines for future design of similar systems.

A novel membrane bioreactor enhanced by effective microorganisms for the treatment of domestic wastewater

The activated sludge membrane bioreactor (MBR) has been shown to have some advantages for the processing and reclamation of domestic wastewater. We hypothesized that certain microorganisms, chosen for their abilities to decompose the chemical components of raw sewage, would, when coupled with the MBR, significantly improve the stability and efficiency of this system. We selected environmental bacterial strains which oxidize ammonia and nitrites and produce protease, amylase, and cellulase for the development and testing of a novel biologically enhanced MBR (eMBR). We compared the eMBR with the activated sludge MBR. With the eMBR, the average values of effluent quality were: chemical oxygen demand (COD), 40 mg/l(average efficiency of removal 90.0%); and NH(4) (+)-N, 0.66 mg/l(average efficiency of removal 99.4%). Effluent qualities met the standard and were stable during the entire 90 days of this study. For the activated sludge MBR, the COD removal rate was 91.7%, and the NH(4) (+)-N removal (94.8%) was less than that of the eMBR. Start-up time for the eMBR was only 24-48 h, much shorter than the 7-8 days required to initiate function of the standard MBR. The biomass concentrations of total heterotrophic bacteria and autotrophic bacteria in the eMBR did not fluctuate significantly during the course of the study. Various kinds of microorganisms will establish an ecological balance in the reactor. Compared with the activated sludge MBR, the eMBR not only produced an excellent and stable quality of effluent but also resulted in a shorter time to start-up and significantly improved the efficiency of NH(4) (+)-N removal.

Organic and detergent degradation in combined O3/UF for domestic laundry wastewater reclamation

This paper focuses on the evaluation of organic and detergent degradation in a combined Ozone/UF system for domestic laundry wastewater reclamation. Formation of by-product was investigated by GC/MS for the reclaimed water. Ozone was injected into the raw wastewater in a 10 L contact tank and the wastewater was circulated through the membrane module for inner pressurized cross-flow filtration. The concentrate was returned back to the contact tank. The membrane used in this experiment was hollow fiber polysulfone UF membrane with MWCO 10,000. It has an effective filtration area of 0.06 m2. The experiment was carried out with intermittent ozone injection, 5 min injection and 10 min idling. Ozone was dosed at the concentration of 1.5 mg/L. The flux of the UF could be maintained at 0.24 m/d under filtration pressure 40-45 kPa and water temperature, 20-22 degrees C. The organic removal efficiency by the system was 90% in terms of COD. Ozone was considerably effective to degrade organics in the wastewater. Molecular weight of organics in the raw waste was mostly greater than 10,000 (72% of 950 mgCOD/L). However 86% of effluent COD (94-100 mg/L) was composed of organics smaller than MWCO 500 by ozone injection. No harmful by-products by ozone contact were detected from the analysis of treated water using GC/MS. It was identified that residual organics in the treated water were 1,1'-Oxybisbenzene, Octadecanoic acid, Squalene and Benzenmethanol, etc., which were additives contained originally in the detergent. Consequently the reclaimed water quality could be estimated safe enough to recycle for the rinsing cycle in a washing machine.

Domestic wastewater reclamation by submerged membrane bioreactor with high concentration powdered activated carbon for stream restoration

This study focuses on the practical application of high concentration powdered activated carbon coupled membrane bio-reactor to domestic wastewater reclamation. The study was conducted in three parts, such as analysis of secondary domestic wastewater effluent, design and operation parameter evaluation and reclaimed water quality estimation for stream restoration. The organic concentration was 25.2-80.2 mgCOD(Cr)/L for the effluent of three domestic wastewater treatment plants. Around 50-75% of the COD was low molecular substances less than 1,000 which were quite biodegradable. The sawdust PAC was estimated to be proper adsorbent for the organics in the secondary effluents. Its Freundlich constant, K value was 5.847 and 1/n, 0.36. Using a system consists of single reactor with high concentration PAC (80 g/L) and submerged hollow fiber MF membrane module with nominal pore size of 0.1 microm, design and operation parameters were obtained, such as HRT of the bioreactor (2.5 hr), PAC concentration (80 g/L), the initial flux (less than 0.5 m/day) and intermittent suction cycle (12 min. suction and 3 min. idling). Organic removal by the system was high enough to produce reclaimed water for urban stream restoration The effluent organic concentration was at the level of 2 mg/L in terms of TOC (around 5 mg/L as COD(Cr)). Substances with molecular weight cut off < 1,000 were removed mostly by adsorption and biodegradation. Those above 1,000 were rejected at PAC cake layer on the membrane and gradually degraded by microorganisms during extended contact.

Combining UASB technology and constructed wetland for domestic wastewater reclamation and reuse

The enhancement of water quality by constructed wetland systems is increasingly being employed throughout the world. For this study two treatment schemes consisting of an Up-flow Anaerobic Sludge Blanket (UASB) reactor followed by either subsurface flow (SSF) or free surface flow (FSF) constructed wetlands have been investigated. The common macrophyte in Egypt Typha latifolia (cattail) was used at a planting density of three rhizomes/m2. To evaluate the role of plants in the treatment process, an unplanted gravel bed identical to the SSF unit was operated as control. During the study period, the wetlands were fed with the UASB effluent at an organic loading rate ranging from 17.3 to 46.8 kg BOD5/ha·d (55.1 to 134.6 kgCOD/ha·d). Effectiveness of the system for the removal of key constituents (COD, BOD, TSS, nutrients and FC) has been investigated. The results showed that, the level of CODtot, and TSS in the final effluent of SSF was lower than that of FWS. Subsurface flow wetland has demonstrated higher overall efficiency than the unplanted control. FC reduction reached 4 log units. Further studies are on-going to optimize the wetland design under local environmental conditions.

Case studies on municipal wastewater reclamation and reuse in China

Water shortage and water environmental pollution have promoted the development of wastewater reclamation and reuse in China in recent years. Different treatment processes are employed for this purpose, such as pond-farmland systems using solar radiation as initial energy source, treating wastewater at low cost and low energy consumption to realize wastewater reclamation and reuse for irrigation on farmland to provide both water and nutrients. Some full-scale projects on municipal wastewater reclamation mainly based on activated sludge and/or submerged biofilm processes followed by some advanced treatment processes such as filtration and disinfecting, from which the effluent is reused in agriculture, industry and domestic uses except for drinking purpose have been built and put into operation in some water shortage cities, which are described in this paper. In some water scarce cities the domestic wastewater reclamation and reuse (dual water system) is employed for a building, a group of buildings or a sub-residential district, whose treatment system consists of submerged biofilm process, dual-media filter and disinfection.