Greywater Effluent Research Articles

Remarks on sustainable disposal and potential reuse of greywater in an informal urban settlement, Cape Town, South Africa

Background The disposal of greywater is a challenge for informal urban settlements that do not have a reticulation system to collect the wastewater they generate. Greywater, which includes domestic wastewater, represents a potential resource that can alleviate water stress if efficiently managed. This study aimed to provide sustainable disposal and potential reuse of greywater produced using informal settlements in Cape Town, South Africa. Greywater has the potential to contribute significantly to food security in such settlements by providing a source of both irrigation water and toilet flushing. Methods A combination of desktop research and interviews was employed to gather and analyze the data. A total of 69 questionnaires were administered in the study, and greywater management practices were investigated. Results The findings showed deficiencies in the sustainable disposal of greywater from households. To understand the volumes of greywater generated from a household, a model has been proposed in the study, as there has been a lack of focus on making predictions that quantify the volume of greywater recovered from these households. Conclusions In the context of sustainable development, water management, and considering the scarcity of water resources, particularly in semi-arid regions, the use of treated greywater is an alternative method that can reduce the burden of withdrawals. The study has demonstrated that socio-economic status and education level has reciprocal outcomes on the communities’ understanding of environmental issues. Eliminating inappropriate disposal and providing means to sustainable reuse of greywater effluent is the key.

Retention of micropollutants by polyelectrolyte multilayer based hollow fiber nanofiltration membranes under fouled conditions

To meet the increasing global water demand, local solutions, such as the reuse of greywater, are becoming of greater importance. While greywater reclamation has been implemented, full-scale adaptation has been limited by the occurrence of micropollutants in treated greywater effluent. To reduce the risks posed by micropollutants, advanced post-treatment is required. One promising technology is the implementation of hollow fiber nanofiltration, which has proven to effectively remove micropollutants. However, the effect of fouling on the overall membrane performance has received limited attention. In this research, the effect of fouling on the performance of polyelectrolyte multilayer nanofiltration membranes was evaluated. Filtration experiments were performed using hollow fiber nanofiltration membranes using model solutions and greywater effluent. Synthetic greywater effluent with different model foulants was implemented to simulate bio- and colloidal fouling. Afterwards, the fouling propensity of greywater effluent from a source-separated treatment plant was evaluated. The performed experiments demonstrated that the studied hollow fiber nanofiltration membranes are mainly sensitive to biofouling. Permeability loss was observed in all foulant experiments, and overall, sodium alginate most severely reduced the flux. Regardless of the loss in permeability, micropollutant retention remained relatively constant, demonstrating the potential suitability of hollow fiber nanofiltration membranes in greywater reclamation schemes.

Sequential biological and solar photocatalytic treatment system for greywater treatment.

In this study, sequencing batch reactor (SBR) using anaerobic/aerobic/anoxic process was coupled to a solar photocatalytic reactor (SPCR) for greywater treatment. The greywater effluent from SBR (operated at the optimal condition: 6.8 h hydraulic retention time (HRT), 0.7 Volumetric exchange ratio (VER) and 7.94 d solids retention time (SRT) with optimal corn cob adsorbent dosage (0.5 g/L)) was fed to the SPCR (operated at optimal conditions: pH - 3, H2O2 dosage - 1 g/L, catalyst dosage - 5 g/L). Chemical oxygen demand (COD) removal of 92.8±0.5% and ∼100% were achieved in SBR and SBR-SPCR, respectively. Similarly, total organic carbon (TOC) removal of 91±0.9% and ∼100% were observed in SBR and SBR-SPCR, respectively. After SBR treatment, average total nitrogen (TN) removal of 84% was found and this TN removal increased to 93% after combined SBR-SPCR treatment. The maximum PO43-_P reduction of 80±1.5% % was achieved with SBR-adsorption system. In addition, a maximum of 87±0.9% of net PO43-_P removal was reached after SBR-SPCR treatment. 58.9±2.3% BP (benzophenone-3) removal was obtained in the SBR while the integration of SBR and SPCR treatment was resulted in 100% BP removal. An effective anionic surfactant (AS) removal rate (80.1±2.2%) was observed in the SBR phase, which further improved to 94.9±1% at the end of 4 h SPCR treatment.

Constructed wetlands with Cyperus alternifolius as a sustainable solution for household greywater treatment

Compared to the conventional wastewater treatment plants, constructed wetlands (CWs) are low-cost and affordable green technologies for treating many types of wastewater. This study aimed to evaluate the sustainability of an old-single CW, after four years of operation, and compare its performance with a new-smaller CW, using Cyperus alternifolius plant and applying Hydraulic Retention Time (HRT) for one day. Two artificial wetlands, namely CW-B and CW-S, were used with dimensions (length x width x height) of 170 x 70 x 70cm and 71 x 42.5 x 52.5cm, respectively. The first operation of the CW-B was in September 2015 and the CW-S was in April 2019. Several concentrations of household greywater influent were loaded into the CWs to analyze their performance. Two aeration pipes were installed in the wetland system to increase the oxygen level in the systems. Water quality parameters namely Biological Oxygen Demand (BOD), Total Suspended Solid (TSS), detergent, and Dissolved Oxygen (DO) were laboratory tested before and after treatment. Research carried out during April to October 2019 resulted in the mean removal efficiencies for CW-B and CW-S being 94.13% and 96.84% for BOD; 95.04% and 95.62% for TSS; 97.11% and 94.61% for detergent; and 99.5% and 79.7% for DO increase, respectively. These findings indicate that the removal efficiencies of those parameters in both wetlands were not significantly different. Hence, the system of the old CW-B wetland still keeps a good working process. Referring to the national standards of water quality, the greywater effluents were safely discharged into water bodies and could be used for irrigation needs. A further study needs to be developed to maximize the detergent removal to meet the existing standard for hygiene sanitation. These results suggest that CWs are becoming a sustainable solution for the treatment of greywater at the household level and finally contributing to minimizing the pollution of water.

Treatment of domestic greywater using fly ash as an adsorbent incorporated in a slow sand filtration system

AbstractThis study investigated the use of fly ash for treatment of domestic greywater when incorporated in a small-scale slow sand filtration (SSF) system. The system was designed, constructed, and tested for treating domestic grey water for irrigation purposes. Configuration A of the system contained sand and gravel only, while configuration B contained fly ash, sand, and gravel. The greywater samples used to test the designed system were collected from the student hostels at the Copperbelt University in Zambia. Additionally, physical and chemical characterisation of the fly ash was done and all key characteristics are presented under the results and discussion section. The system that contained fly ash considerably improved the greywater quality for irrigation purposes by reducing turbidity by 95%, colour by 98%, and chloride by 49% and increasing dissolved oxygen by 33%. However, pH, total dissolved solids, and electrical conductivity were observed to be slightly higher in the treated greywater effluent. The slight increase in these parameters is suspected to have been caused by possible leaching from the the fly ash. Therefore, obtaining fly ash from sources that may not cause any increase in the said parameters in the treated effluent is recommended to maintain compliance with irrigation water quality.

Photocatalytic Removal of Pharmaceuticals from Greywater

High concentrations of pharmaceuticals have been detected in greywater effluents treated using up-to-date technologies. Finding a suitable additional treatment before this effluent is reused is urgently needed to ensure the reused water meets quality standards. This paper reports the use of heterogeneous photocatalysis on anatase and rutile nanopowders to remove naproxen, metformin and sulfamethoxazole, at practically relevant concentrations found in membrane bioreactor (MBR)-treated greywater. A low anatase concentration of 400 mg L−1 was sufficient to efficiently degrade the pharmaceuticals listed above, with complete degradation observed in 5 h. The effect of background species presented in greywater was, to some extent, comparable to that of the OH-radical scavenger. These results prove that photocatalysis using anatase TiO2 is a feasible additional treatment for greywater recycling.

Polymer-based immobilized Fe2O3–TiO2/PVP catalyst preparation method and the degradation of triclosan in treated greywater effluent by solar photocatalysis

The present study involves a novel protocol to develop a ternary composite catalyst for an effective post-treatment technique for greywater. The ternary film of Fe2O3–TiO2/polyvinyl pyrrolidine (PVP) is coated on a glass tube using spray coating with annealing at 320 °C. The structure, thermal, microstructure, and surface properties of the coated film are characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Thermo Gravimetric Analysis (TGA). The scratch hardness of photocatalysts at different Fe2O3/TiO2 compositions is investigated based on the width measurement of scratch using FESEM analysis. Results show that at an optimum coating of 5% of Fe2O3/TiO2 composition catalytic film, the maximum scratch hardness (7.984 GPa) is obtained. Also, the photocatalyst has the highest cohesive bond strength and wearing resistance. The degradation of triclosan (TCS) in treated greywater, discharged from the anaerobic-aerobic treatment system, is investigated at a lab-scale using a solar photocatalytic reactor. The response surface analysis has been performed from the different sets of experimental trials for various optimal parameters. It is observed that the TCS degradation efficiency of 83.27% has resulted under optimum conditions.

Performance analysis of fabricated bio-filtration system for small-scaled greywater treatment: TSS and turbidity removals

River pollution, which is mainly due to excessive drainage of untreated domestic greywater, has becoming a serious concern in both poor and developing areas like Sarawak in the current years. Realizing the vital role of Sarawak rivers, the need to improve the level of pollution, demand for clean freshwater resources, as well as to save cost on household water supply, the greywater generated daily from every household needs to be pretreated for reuse, otherwise, discharged. This further demands for cost-effective pretreatment technology for domestic and residential use. This research, therefore, analyzes the efficiency of a low-cost bio-filtration system which utilizes agricultural wastes, namely rice husk and coconut coir, as bio-filter media to improve the quality of greywater effluent samples in terms of total suspended solids (TSS) and turbidity removals. This paper presents the extended results obtained from the previous research work using the same fabricated pre-treatment system, which consists of six main units i.e. wastewater storage tank, water feed tank, pre-sedimentation tank, bio-filter, post-sedimentation tank and treated water storage tank. The system is operated for six hours to complete several cycles of treatment. At every one-hour interval, both TSS and turbidity levels of the wastewater samples are recorded and the removal performances are evaluated and analyzed. Positive outcomes are attained from this research study such that the rice husk system is able to reduce the TSS and turbidity levels by 49.06% i.e. from 53.00 mg/L to 27.00 mg/L with an average rate of 4.33 mg/L.hr, as well as 57.79% i.e. from 41.70 FNU to about 17.60 FNU, at a rate of 4.02 FNU/hr respectively. Besides, the coconut coir bio-filtration system achieves TSS removal efficiency of 49.70% i.e. from 65.60 mg/L to 33.00 mg/L at mean rate of 5.43 mg/L.hr, and 63.10% turbidity removal i.e. from 48.40 FNU to 17.86 FNU, at 5.09 FNU/hr respectively.

Reusability performance of green zinc oxide nanoparticles for photocatalysis of bathroom greywater

Abstract This study aims to investigate the potential of green zinc oxide nanoparticles (ZnO NPs) in reusability performance for photocatalysis of bathroom greywater. It was found that ZnO NPs photocatalytic treatment of real bathroom greywater (RBGW) effluent reduces both the COD and BOD5 concentrations by 72.01, 62.75 and 57.79% (COD) and 70.18, 60.32 and 57.56% (BOD5) respectively for the first, second and third cycle. Meanwhile for the photocatalysis of ABGW, it was observed that COD and BOD5 were removed by 82.27, 68.27 and 60.96% (COD) and 82.91, 74.37 and 60.39% (BOD5) for the first, second and third cycle respectively. Besides, TSS and turbidity were reduced by 52.34, 46.85 and 37.98% (TSS) and 80.38, 67.65 and 56.81% (turbidity) respectively in RBGW and for ABGW, TSS and turbidity were reduced by 60.94, 52.37 and 41.95% (TSS) and 80.68, 72.63 and 69.91% (turbidity) for the first, second and third experimental run respectively. This designates that green ZnO NPs can be reused multiple times as an effective photocatalyst. However, ZnO NPs were used in the dispersed form, which causes difficulty in the separation of ZnO NPs from the greywater. Thus, further investigation in producing appropriate fixed film should be focused. Moreover, phytotoxicity analysis of V. radiate seeds in the treated ABGW and RBGW was not significantly different from their germination in water. This assured the less lethal nature of the degradation metabolites in greywater effluent. This investigation would be a solution to wastewater treatment plant for reusing photocatalyst in order to achieve the development of advanced and greener technologies.

Antibiotic-resistant Escherichia coli and Klebsiella spp. in greywater reuse systems and pond water used for agricultural irrigation in the West Bank, Palestinian Territories

Treating and reusing greywater for agricultural irrigation is becoming increasingly prevalent in water-scarce regions such as the Middle East. However, the potential for antibiotic-resistant bacteria to be introduced into food systems or the environment via greywater reuse is a potential area of concern. It is known that off-grid treated greywater often has elevated levels of bacteria, however, little is known regarding the prevalence of antibiotic-resistant bacteria in this water source. To address this knowledge gap, samples (n = 61) of off-grid, household greywater (influent), treated greywater effluent, and irrigation pond water were collected between October 2017 and June 2018 from four farms in the West Bank, Palestinian Territories. Samples were tested for pH, turbidity, dissolved oxygen, electrical conductivity, and oxidation reduction potential. Standard membrane filtration was used to enumerate presumptive Escherichia coli, and isolates (n = 88) were purified, confirmed using 16S rRNA sequencing, and subjected to antimicrobial susceptibility testing using microbroth dilution. The majority of influent (76.5%) and effluent (70.6%) samples had detectable presumptive E. coli. Interestingly, the majority of the isolates were confirmed as Klebsiella sp. (n = 37), followed by E. coli (n = 32), and the remainder were classified as other Enterobacteriaceae (n = 19). A higher percentage of effluent isolates were fully susceptible to all tested antibiotics when compared to influent isolates (28.6% vs 18.6%). Resistance was most commonly observed against ampicillin (69.3% of all isolates), trimethoprim-sulfamethoxazole (11.4%), tetracycline (9.1%), and cefazolin (7.9%), and 7.9% of isolates were observed to be multidrug-resistant. While most water quality parameters were within Israeli and Palestinian wastewater reuse requirements, E. coli levels in effluent violated available standards. These findings suggest that, despite observed decreases in bacteria and an overall decrease in isolates expressing antibiotic resistance from influent to effluent, off-grid greywater treatment systems are still a potential source of both susceptible and antibiotic-resistant bacteria in the agricultural environment.

Effects of treated greywater irrigation regimes and mulches on yield of Capsicum chinense under surface drip irrigation system

A field study was conducted to determine the effects of combine treatment of greywater application rates and mulches types on growth and yield of Capsicum chinense in Omu-Aran, Nigeria. Greywater (GW) was treated using a pilot-scale horizontal sub-surface flow constructed wetlands (HSSF CW) vegetated with Canna indica plants. Four irrigation levels (60, 80, 100 and 120% of ETc) and four mulches types (Black plastic film BM, Silver plastic film SM, Rice straw RS and un-mulched Control) were applied to the potted plants. The experiment was laid out in a split-plot design, with main plots as irrigation levels and mulches types as sub-plots. C. indica plants were found to be effective in GW Phytoremediation treatment in CW. The maximum fruit yield was observed for T10 (I100SM) 4666.70 kg/ha due to reflective mulch ability to increase light and heat to plant resulting to a higher yield. Significant difference was observed between the mean yield of I60 and other irrigation regimes, whereas between I80 to I120 there was no significant difference in mean yield recorded. Silver mulch combined with full irrigation with treated greywater effluent was found to be the best of all treatments in the study.

Antibiotic and herbicide concentrations in household greywater reuse systems and pond water used for food crop irrigation: West Bank, Palestinian Territories

Greywater is increasingly treated and reused for agricultural irrigation in off-grid communities in the Middle East and other water scarce regions of the world. However, there is a dearth of data regarding levels of antibiotics and herbicides in off-grid greywater treatment systems. To address this knowledge gap, we evaluated levels of these contaminants in two types of greywater treatment systems on four farms in the West Bank, Palestinian Territories. Samples of household greywater (influent, n = 23), treated greywater effluent intended for agricultural irrigation (n = 23) and pumped groundwater held in irrigation water ponds (n = 12) were collected from October 2017 to June 2018. Samples were analyzed using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) for the following antibiotics and herbicides: alachlor, ampicillin, atrazine, azithromycin, ciprofloxacin, erythromycin, linezolid, oxacillin, oxolinic acid, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, tetracycline, triflualin, and vancomycin. All tested antibiotics and herbicides were detected in greywater influent samples at concentrations ranging from 1.3 to 1592.9 ng/L and 3.1–22.4 ng/L, respectively. When comparing influent to effluent concentrations, removal was observed for azithromycin, alachlor, linezolid, oxacillin, penicillin G, pipemidic acid, sulfamethoxazole, triclocarban, and vancomycin. Removal was not observed for atrazine, ciprofloxacin, erythromycin, oxolinic acid, tetracycline, and trifluralin. Pond water also contained the majority of tested contaminants, but at generally lower concentrations. To our knowledge, this is the first description of an extensive array of antibiotics and herbicides detected in household greywater from off-grid treatment systems.

Effect of fly ash-lime treatment on the acute toxicity of greywater towards Daphnia magna

Abstract Acute toxicity of raw and treated greywater towards Daphnia magna was assessed in this study. Treatment was performed with exposure of greywater to the fly-lime mixture After 48 h of exposure, 100 % mortality of D. magna was recorded when testing the following volumetric fractions of the raw greywater streams in the tested liquid medium (%; v/v): 10 % for kitchen greywater, 5 – 10 % for bathroom greywater and 1.25 – 10 % for laundry greywater. After greywater treatment with the fly-ash-lime mixture with pH adjustment to 7.0, 80 % of neonates of D. magna survived after exposure to treated laundry greywater in all dilutions at 48 h. At the same time, 100 % of neonates survived exposure to treated bathroom and kitchen greywater at all volumetric fractions. Therefore greywater had acute toxicity to D. magna, i.e. greywater treatment was required before its discharge or reuse. Values of the Pearson’s correlation coefficient between the chemical components of the raw greywater and treated greywater and the survival of D. magna indicated a lack of statistically significant correlation at 5 % level of significance (p-value > 0.05 in all cases), i.e. the survival of D. magna was independent of the concentration of chemical constituents in greywater samples tested. Further studies will have to be conducted on the chronic toxicity of the greywater effluent after treatment with the fly-lime mixture. Experiments from this study will have to be re-run for the fully scaled-up version of the fly-lime mixture-based greywater treatment systems.

Evaluation of photocatalytic fuel cell (PFC) for electricity production and simultaneous degradation of methyl green in synthetic and real greywater effluents

Recycling of alternative water sources particularly greywater and recovery of energy from wastewater are gaining momentum due to clean water scarcity and energy crisis. In this study, the photocatalytic fuel cell (PFC) employing ZnO/Zn photoanode and CuO/Cu photocathode was successfully designed for effective greywater recycling as well as energy recovery. The photoelectrodes were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and fourier transform infrared (FTIR) spectroscopy. The PFC performance in terms of electricity generation and parallel methyl green (MG) degradation were evaluated under operating parameters such as electrolyte type, initial MG concentration and solution pH. The results showed that the addition of Na2SO4 electrolyte, MG concentration of 40 mg L−1 and solution pH of 5.2 improved the short circuit current density (Jsc) and power density (Pmax) in the as-constructed PFC. Such a system also afforded highest MG and chemical oxygen demand (COD) removal efficiencies after 4 h of irradiation. The photoanodes used in this study demonstrated great recyclability after four repetition tests. The COD removal was reduced to some extents when the PFC treatment was tested in the real greywater under optimal conditions. Various greywater quality parameters including ammoniacal nitrogen (NH3–N), turbidity, pH and biochemical oxygen demand (BOD5) were also monitored. The phytotoxicity experiments via Vigna radiate seeds indicated a reduction in the phytotoxicity.

Photocatalytic ozonation under visible light for the remediation of water effluents and its integration with an electro-membrane bioreactor

Photocatalysis and photocatalytic ozonation under visible light have been applied for the purification of a complex aqueous matrix such as the grey water of Masdar City (UAE), by using N-doped brookite-rutile catalysts. Preliminary runs on 4-nitrophenol (4-NP) solutions allowed to test the reaction system in the presence of a model pollutant and to afford the relevant kinetic parameters of the process. Subsequently, the remediation of grey water effluent has been evaluated in terms of the reduction of total organic carbon (TOC) and bacterial counts. The concentration of the most abundant inorganic ionic species in the effluent has been also monitored during reaction. Photocatalytic ozonation under visible light allowed to reduce the TOC content of the grey water by ca. 60% in the optimized experimental conditions and to reduce the total bacterial count by ca. 97%. The extent of TOC mineralization reached ca. 80% when the photocatalytic ozonation occurred downstream to a preliminary electro-membrane bioreactor (eMBR). Coupling the two processes enhanced the global efficiency. In fact, the eMBR treatment lowered the turbidity and the organic load of the effluent entering the photocatalytic ozonation treatment, which in turn enhanced the extent of purification and disinfection.

SIMULATING THE IMPACTS OF INDOOR VERTICAL FLOW CONSTRUCTED WETLANDS ON HVAC PERFORMANCE USING eQUEST AT HAMPSHIRE COLLEGE'S R. W. KERN CENTER

INTRODUCTION Hampshire College, in Amherst, Massachusetts, is taking part in the green building movement with the construction of the R. W. Kern Center, which opened in the spring of 2016. The building was certified to meet the Living Building Challenge in spring 2018 and has satisfied building standards such as Net Zero energy and water. To meet these standards, the design of the building employs solar photovoltaic panels, a rain water catchment and purification system, a greywater treatment system, storm water infiltration rain gardens, composting toilets, and control monitoring systems to make the building more efficient and decrease its harmful impacts on the environment. The greywater treatment system utilizes both indoor vertical flow constructed wetlands (VFCW) and an outdoor horizontal flow constructed wetland (HFCW) to filter greywater effluent from sinks and a coffee bar, meeting the requirement to treat and handle all wastewater generated on site. Although the VFCW system performance has been shown to be effective in exterior environments (Sklarz et al., 2009), its use inside a building requires scrutiny to verify that the adoption of this system does not affect the operation of essential building systems. The green systems that the Kern Center and others like it are employing may have impacts on the building's environment, construction and operation. These modifications must be monitored, and their effects quantified. The alteration of the thermal and air quality characteristics of the interior building has a significant effect on occupant health and the heating, ventilation and air conditioning (HVAC) energy on consumption. Several studies have investigated the benefits of indoor plants for air filtration or for exterior greywater filtration.

Bathroom greywater recycling using polyelectrolyte-complex bilayer membrane: Advanced study of membrane structure and treatment efficiency

Polyelectrolyte-complex bilayer membrane (PCBM) was fabricated using biodegradable chitosan and alginate polymers for subsequent application in the treatment of bathroom greywater. In this study, the properties of PCBMs were studied and it was found that the formation of polyelectrolyte network reduced the molecular weight cut-off (MWCO) from 242kDa in chitosan membrane to 2.71kDa in PCBM. The decrease in MWCO of PCBM results in better greywater treatment efficiency, subsequently demonstrated in a greywater filtration study where treated greywater effluent met the household reclaimed water standard of <2 NTU turbidity and <30ppm total suspended solids (TSS). In addition, a further 20% improvement in chemical oxygen demand (COD) removal was achieved as compared to a single layer chitosan membrane. Results from this study show that the biodegradable PCBM is a potential membrane material in producing clean treated greywater for non-potable applications.

Optimizing the in-line ozone injection and delivery strategy in a multistage pilot-scale greywater treatment system: System validation and cost-benefit analysis

Greywater is a potential source of recycled water for household that has often been overlooked. Although greywater is lightly contaminated, a holistic treatment and disinfection system of greywater is still warranted to ensure public health issues associated with the cross-connection of third pipe reticulation in household are minimized. This study assessed on the treatment performance of a commercial pilot-scale greywater treatment system comprising of a multi-medium sand filter, granulated activated carbon (GAC) filter and an ozonation disinfection system. The operational volume flow rate (10–20L/min) and ozone dosing rate (5–20g/h) for maximum removal of contaminants in greywater were investigated. This study found that the increase in operational volume flow rate decreased the overall performance of the greywater treatment and disinfection system. The optimum operating volume flow rate was found to be 10L/min, removing 72.6% of chemical oxygen demand (COD) and 42.9% (0.85-log removal) of Escherichia coli without recirculation. Recirculation of greywater was introduced to the ozonation disinfection system in order to improve the disinfection efficiency. It was found that all bacteria present in the treated greywater effluent were completely disinfected with a recirculation period of 1h.

Evaluation of Titanium dioxide photocatalytic technology for the treatment of reactive Black 5 dye in synthetic and real greywater effluents

Reuse of alternative water sources is gaining impetus as an acceptable integrated water resources management practice due to the scarcity of freshwater resources, particularly in urban centres where population is dense and freshwater supply is limited. This study investigated on the practical application of titanium dioxide (TiO2) photocatalytic treatment technology as a standalone system for the removal of Reactive Black 5 (RB5) dye, which usually causes a serious aesthetic problem that depresses the wider social acceptance of greywater recycling and reuse schemes. An optimization study was conducted on the photocatalytic degradation of RB5 dye in synthetic greywater effluent (i.e. aqueous RB5 in distilled water), in order to understand the effects of different photoreactor parameters on the degradation kinetics. It was found that the optimum photoreactor operating conditions are at TiO2 loading of 0.1 g/L, pH 5, initial RB5 concentration of 1 ppm and without compressed air sparging. Results showed that a 97% removal of RB5 was evident after 150 min of photocatalytic reaction in synthetic greywater effluent. With the established optimum photoreactor conditions, the photocatalytic degradation kinetics of RB5 dye in real greywater effluent was subsequently investigated. Results showed that the photocatalytic degradation of RB5 in real greywater effluent has a lower removal efficiency of 76% even after 330 min of reaction. It was hypothesized that the presence of other water pollutants in real greywater effluent could compete for the surface binding sites owing to the non-specific nature of TiO2 photocatalytic reaction. Thus, other greywater quality parameters such as oil and grease (O&G), chemical oxygen demand (COD), biological oxygen demand (BOD5), total nitrogen (TN) and total number of Escherichia coli were also monitored. Monitoring results showed that the parallel removal efficiencies of 60% O&G, 54% COD, 69% BOD5, 41% TN and 100% E. coli were evident, which have proven the impact of water impurities in real greywater effluent that could lower the photocatalytic degradation efficiency of RB5.

The Use of Natural Filter Media Added with Peat Soil for Household Greywater Treatment

AbstractGreywater is wastewater that produces 50-80% of overall water consumption in a house. In many village houses of Malaysia, the household greywater that comes from kitchen, laundry, bathroom and sinks is usually untreated and discharged directly into streams or rivers. This phenomenon escalates the pollution among Malaysian rivers. This study examines the effects of household greywater treated with locally available peat soil. This study was performed by using a two-stage filter media (i) pretreatment (gravel + sand) (ii) peat based (peat + charcoal + gravel). Effects of filtration on the peat soil were examined via the one-dimensional consolidation test and X-Ray Fluorescence Test (XRF). Removal efficiency of the greywater effluent was found to be TSS- 81%, BOD- 54%, COD – 52% and AN - 87%. pH of the greywater was improved from acidic (4.6) to neutral (6.9). Quality of the treated greywater complied with the limits of the Malaysian Standard (Standard B) for wastewater effluent discharge. The consolidation test was affected and became slower. XRF test indicates that peat soil has an increased amount of the inorganic content of Silicon Dioxide (SiO2) and Aluminium Oxide (Al2O3) associated with the absorption of certain elements in greywater. The peat based filter resulted in a substantial removal of pollutants. Further study is needed to look in depth the mechanism of adsorption and its applicability in a large scale processes.