On-site Wastewater Treatment Plants Research Articles

A study of continuous-flow electrocoagulation process to minimize chemicals dosing in the full-scale treatment of plastic plating industry wastewater

A continuous-flow electrocoagulation unit was used to replace the existing chemical coagulation in plastic plating industry wastewater treatment plants, aiming to enhance pollutant removal and cost efficiency. This study was conducted at an on-site wastewater treatment plant, with the electrocoagulation process monitored for nine consecutive months. A novel electrocoagulation unit equipped with multi-rod helical systems (i.e., made of an iron anode and a stainless-steel cathode) was used in this study, with the treatment flow adjusted to optimize the operational costs. The results indicate that energy consumption can be maintained at 7200 kWh/month while achieving >99 % removal of heavy metals (Cr, Ni, and Cu), with removal rates of 78.64 ± 0.13 mg/L.day (Cr), 105.47 ± 0.07 mg/L.day (Ni), and 38.30 ± 0.09 mg/L.day (Cu). The chemical cost was reduced by approximately 50 %. Furthermore, an over 50 % reduction in sludge production was achieved, with the acid and alkaline by-products entirely recycled. Compared to the previously applied chemical coagulation, electrocoagulation can reduce operational costs from US$ 6.11 to US$ 2.87 per m3 of wastewater treated. These results confirm that electrocoagulation can be optimized and implemented to replace conventional chemical coagulation.

Free-floating extracellular DNA (exDNA) in different wastewaters: Status quo on exDNA-associated antimicrobial resistance genes

Wastewater treatment plants (WWTPs) have been reported as major anthropogenic reservoirs for the spread of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) into the environment, worldwide. While most studies mainly focus on the intracellular DNA (iDNA), extracellular DNA (exDNA) accounting for a significant proportion of the total DNA in wastewater, was usually neglected. Following the One Health approach, this study focuses on wastewaters of municipal, clinical, and livestock origins (n = 45) that undergo different treatment processes (i.e., conventional activated sludge, ultrafiltration, and ozonation). Water samples were analysed for 12 ARGs as indicators of the different compartments associated with iDNA and exDNA by quantitative real-time PCR (qPCR). Taxonomic profiling of exDNA-fractions, obtained using nucleic acid adsorption particles, was conducted by sequencing the V3–V4 hypervariable regions of the 16S rRNA gene. Notified exDNA concentrations varied between on-site WWTPs and treatment stages, and ranged from 314.0 ± 70.2 ng/mL in untreated livestock wastewater down to 0.7 ± 0.1 ng/mL in effluents after ultrafiltration. In general, influents exhibited higher concentrations compared to effluents, while wastewater treated by advanced treatment processes (i.e., ultrafiltration and ozonation) showed the lowest exDNA concentrations. Despite the lower concentrations, free-floating exDNA accounted for up to 80.0 ± 5.8% of the total DNA in effluents. Target ARGs were more common in the iDNA (100%, n = 45/45), compared to the exDNA-fractions (51.1%, n = 23/45), whereas exDNA-ARGs were mostly detected in clinical and slaughterhouse wastewaters as well as in the municipal influents. Compared to the iDNA-ARGs, the concentrations of exDNA-ARGs were in general lower. Nevertheless, significant higher concentrations for exDNA-associated genes were measured in clinical wastewaters for blaNDM (4.07 ± 0.15 log gene copies (GC)/L) and blaVIM-2 (6.0 ± 0.2 log GC/L). Overall, our results suggest that depending on the origin of wastewater and its treatment methods, exDNA represents an important reservoir for ARGs, particularly in clinical wastewater.

Use of Shredded Recycled Plastic as Filter Bed Packing in a Vertical Flow Filter for Onsite Wastewater Treatment Plants: Preliminary Findings

Household wastewater is a problem, especially in areas with a dispersed settlement where there is no wastewater collection system or wastewater treatment plant. In this case, it is necessary to build a local or onsite wastewater treatment plant. This paper is an attempt to analyse the possibility of using recycled shredded ABS plastic (acrylonitrile butadiene styrene) as packing media in an experimental vertical flow filter for use in on-site wastewater treatment plants. Studies have shown that shredded recycled ABS is a promising filtration material that has several features important in the treatment process, like a large surface area, high mechanical strength and chemical inertness. The system was operated with a hydraulic load of 50 dm3/m2 (3 months). BOD5 (biochemical oxygen demand), COD (chemical oxygen demand), and total suspended solids (TSS) reduction efficiency in the primary effluent was high; 94.4%, 77.8%, and 92.8%, respectively.

Several Small or Single Large? Quantifying the Catchment-Wide Performance of On-Site Wastewater Treatment Plants with Inaccurate Sensors.

On-site wastewater treatment plants (OSTs) often lack monitoring, resulting in unreliable treatment performance. They thus appear to be a stopgap solution despite their potential contribution to circular water management. Low-maintenance but inaccurate soft sensors are emerging that address this concern. However, how their inaccuracy impacts the catchment-wide treatment performance of a system of many OSTs has not been quantified. We develop a stochastic model to estimate catchment-wide OST performances with a Monte Carlo simulation. In our study, soft sensors with a 70% accuracy improved the treatment performance from 66% of the time functional to 98%. Soft sensors optimized for specificity, indicating the true negative rate, improve the system performance, while sensors optimized for sensitivity, indicating the true positive rate, quantify the treatment performance more accurately. This new insight leads us to suggest programming two soft sensors in practical settings with the same hardware sensor data as input: one soft sensor geared to high specificity for maintenance scheduling and one geared to high sensitivity for performance quantification. Our findings suggest that a maintenance strategy combining inaccurate sensors with appropriate alarm management can vastly improve the mean catchment-wide treatment performance of a system of OSTs.

The sustainability of wastewater treatment efficiency and its estimated impact for onsite wastewater treatment plant systems in semi-urban areas: a Khan Yunis case study

The sustainability of wastewater treatment efficiency and its estimated impact for onsite wastewater treatment plant systems in semi-urban areas: a Khan Yunis case study

Detection and Analysis of Microfibers and Microplastics in Wastewater from a Textile Company

Textile wastewater is polluted by inorganic/organic substances, polymers, dyes, and microfibers (MFs), which are microplastics (MPs) and natural fibers. This work is aimed at the preliminary investigation of MFs and MPs in textile industrial wastewater, and at evaluating the removal efficiency of an on-site wastewater treatment plant (WWTP). Ten samples of inflows and outflows of the WWTP of a textile company (applying a physic-chemical process) have been analyzed. Firstly, the samples underwent a pretreatment with 15% hydrogen peroxide at 25 °C for 5 days to remove organic compounds. Secondly, the MFs were recovered from the aqueous phase by pre-screening centrifugation, density separation, and filtration as alternative options. Filtration obtained the best performances, compared to the other recovery processes. Thirdly, the MFs were counted through optical microscopy and the MPs were identified through micro-FTIR. The MFs amount in the inflow samples was in the range of 893–4452 MFs/L. The outflow samples (310–2404 MFs/L) exhibited a 38–65% reduction compared to the inflows, demonstrating that up to 62% of residual MFs can enter the sewer network or the receiving water body. Cotton and wool, and numerous MPs (acrylic, polyester, polypropylene, polyamide, and viscose/rayon) were identified in the inflow and outflow samples (with the only exception of “dense” viscose (rayon), not detected in the outflows, and probably retained by the WWTP with the sludge). This study, even if just preliminary, offers interesting hints for future research on MFs/MPs detection in textile wastewater, and on the performance of a full-scale WWT process for their removal.

Combination of Microscopic Tests of the Activated Sludge and Effluent Quality for More Efficient On-Site Treatment

Container on-site wastewater treatment plants are systems of growing interest in the areas where sewer systems cannot be implemented. In this study, container on-site wastewater treatment plant with low-loaded activated sludge has been examined. The aim of the study was: (i) to assess the efficiency of the plant; and (ii) to evaluate the relationship between the condition of activated sludge and selected parameters of effluent quality. Effluent quality has been characterized by the reliability factor (RF) and technological purity index (TPI). Sludge quality assessment covered measurements of volume (Vo), dry matter (DM), sludge index (SI), and the unit oxygen consumption rate (UOCR). Microscopic analysis has been performed to assess the morphological (flocks) and biotic quality (sludge biotic index, SBI) of activated sludge. The research has been completed by an on-site measurement of dissolved oxygen concentration in an activated sludge chamber with 30 s intervals. Results confirmed a significant (p < 0.05) correlation (CC = −0.9277) between biochemical oxygen demand (BOD5) and SBI for the oxygen level in the aeration chamber between 1–2 mg/L. Negative significant correlation (p < 0.05) has also been found between SBI and electrical conductivity (EC) (CC = −0.7478). In the examined case, the optimal EC of the effluent was in the range of 600–800 µS/cm.

Investigation of the anaerobic digestion of cosmetic industrial wastes: Feasibility and perspectives

This study assessed the anaerobic digestion (AD) of wastes deriving from cosmetics production: sludge from onsite wastewater treatment plant (sWWTP), residues of shampoo/conditioner (RSC) and sludge from mascara production (MS), considered as single substrates and as mixture according to the produced amounts (54 %-wt sWWTP, 31 %-wt RSC, 13 %-wt MS, plus 2 %-wt food waste from the canteen, FW). Total COD (CODT) was 624–1436 g O2/kg VS, while soluble COD was 5–23 %-wt of CODT. AD tests at 35 °C achieved the following biogas yields: 0.10 Nm3/kgvs (70 %-v/v methane) for sWWTP; 0.07 Nm3/kgvs (62 %-v/v methane) for RSC; 0.04 Nm3/kgvs (67 %-v/v methane) for MS. The mixed substrates underwent physico-chemical pre-treatments (thermo-alkaline, TA: 120 min at 50 °C; thermo-alkaline-sonication, TAS: 15 min at 40 kHz and 80 °C, both based on the addition of 0.08 g NaOH per each g of total solid in the substrate), reaching 64–66% disintegration rate, and AD tests (5 %-wt dry substance) at 35 and 52 °C. Biogas yields were (for TA and TAS respectively): 0.22 and 0.20 Nm3/kgVS (62–70% methane); 0.21 and 0.19 Nm3/kgVS (66-66% methane) at 52 °C. At both temperatures, methane yields considerably improved (+71–100%), compared to mixed untreated substrates, and 5-8 %-wt total solids reductions were observed. A technical-economic scale-up assessment completed the research. The energy analysis highlighted the crucial role of TA pre-treatment in achieving the process energetic sustainability. The economic analysis showed that the AD of the considered cosmetic waste could be sustainable anyway, thanks to the savings related to the disposal of the digestate compared to current waste management costs.

Assessment of the Efficiency, Environmental and Economic Effects of Compact Type On-Site Wastewater Treatment Plants—Results from Random Testing

This study presents the results of random testing of selected on-site wastewater treatment plants (WWTPs) constructed in Poland in Masovia Voivodship in the years 2011–2016. The vast majority of tested on-site WWTPs were compact (container) type treatment plants, based on low rate activated sludge (AS), sequencing batch reactors (SBR), or a hybrid (activated sludge supported with biological film, AS + BF) method. Compact type plans are becoming more and more popular in single households in Poland, due to the option of co-financing. According to certificates provided by producers and distributors, container on-site wastewater treatment plants are efficient in BOD5 removal, with the expected removal rate being over 80%. The aim of this study was (1) to analyze BOD5 in effluents sampled from randomly selected on-site WWTPs, (2) to evaluate predicted and real environmental effects of the implementation of on-site WWTPs in selected communes within Masovia Voivodship, and (3) to calculate unit environmental and economic effects of container on-site WWTPs in three different technologies. Results of this study show that in most cases, there is a gap between the declared and the real BOD5 removal efficiency. There is also a difference between the performance of different container type technologies. The lowest real environmental effect was obtained for AS technology, and the highest for the hybrid one. The predicted environmental effect has only been almost achieved in the case of hybrid systems. Based on net present value (NPV) benefits, technologies can be set up as follows: AS > SBR > AS + BF, making the AS method the most effective technology from the point of view of the economy.

Performance of viral and bacterial genetic markers for sewage pollution tracking in tropical Thailand

Identifying sewage contamination via microbial source tracking (MST) marker genes has proven useful for effective water quality management worldwide; however, performance evaluations for these marker genes in tropical areas are limited. Therefore, this research evaluated four human-associated MST marker genes (human polyomaviruses (JC and BK viruses [HPyVs]), bacteriophage crAssphage (CPQ_056), Lachnospiraceae Lachno3, and Bacteroides BacV6-21) for tracking sewage pollution in aquatic environments of Thailand. The viral marker genes, HPyV and crAssphage were highly sensitive and specific to sewage from onsite wastewater treatment plants (OWTPs; n = 19), with no cross-detection in 120 composite swine, cattle, chicken, duck, goat, sheep, and buffalo fecal samples. The bacterial marker genes, Lachno3 and BacV6-21, demonstrated high sensitivity but moderate specificity; however, using both markers could improve specificity to >0.80 (max value of 1.00). The most abundant markers in OWTP samples were Lachno3 and BacV6-21 (5.42–8.02 and nondetect–8.05 log10 copies/100 mL), crAssphage (5.28–7.38 log10 copies/100 mL), and HPyVs (3.66–6.53 log10 copies/100 mL), respectively. Due to their increased specificity, the abundance of viral markers were further investigated in environmental waters, in which HPyVs showed greater levels (up to 4.33 log10 copies/100 mL) and greater detection rates (92.7%) in two coastal beaches (n = 41) than crAssphage (up to 3.51 log10 copies/100 mL and 56.1%). HPyVs were also found at slightly lower levels (up to 5.10 log10 copies/100 mL), but at higher detection rates (92.6%), in a freshwater canal (n = 27) than crAssphage (up to 5.21 log10 copies/100 mL and 88.9%). HPyVs and crAssphage marker genes were identified as highly sensitive and specific for tracking sewage pollution in aquatic environments of Thailand. This study underlines the importance of characterizing and validating MST markers in host groups and environmental waters before including them in a water quality management toolbox.

Benchmarking Soft Sensors for Remote Monitoring of On-Site Wastewater Treatment Plants.

On-site wastewater treatment plants (OSTs) are usually unattended, so failures often remain undetected and lead to prolonged periods of reduced performance. To stabilize the performance of unattended plants, soft sensors could expose faults and failures to the operator. In a previous study, we developed soft sensors and showed that soft sensors with data from unmaintained physical sensors can be as accurate as soft sensors with data from maintained ones. The monitored variables were pH and dissolved oxygen (DO), and soft sensors were used to predict nitrification performance. In the present study, we use synthetic data and monitor three plants to test these soft sensors. We find that a long solids retention time and a moderate aeration rate improve the pH soft-sensor accuracy and that the aeration regime is the main operational parameter affecting the accuracy of the DO soft sensor. We demonstrate that integrated design of monitoring and control is necessary to achieve robustness when extrapolating from one OST to another in the absence of plant-specific fine-tuning. Additionally, we provide a unique labeled dataset for further feature and data-driven soft-sensor development. Our benchmarking results indicate that it is feasible to monitor OSTs with unmaintained sensors and without plant-specific tuning of the developed soft sensors. This is expected to drastically reduce monitoring costs for OST-based sanitation systems.

Insights of environmental impact assessment reports for industrial parks: wastewater quantity prediction aspect.

While the contribution of industrial parks to the socio-economic aspect has been widely acknowledged over the past two decades in Vietnam, the problem of environmental pollution due to the wastes generated from industrial parks, especially wastewater, has still been an emerging issue, which places a great pressure on the Government. The wastewater generation from industrial parks was ordinarily required to report in all environmental impact assessment (EIA) reports as a base for the construction of on-site wastewater treatment plants within the industrial park. In Vietnam, this data was, however, often higher than the actual generated number due to inaccurate technical guidelines on predicting wastewater generation and many different methods to be applied. This study aimed to evaluate different approaches used to calculate the effluent in the industrial parks. The results showed that all of the four approaches (i.e., previous operation-based, water-based, wastewater-based, or experience-based methods) rendered significant gaps between predicted and actual values. None can be acceptable for use at present. A revision of technical guideline should be conducted to provide more detailed instruction for the better prediction. This shall minimize the investment capital and increase the efficiency of industrial parks in pollution control.

Engineered silver nanoparticle (Ag-NP) behaviour in domestic on-site wastewater treatment plants and in sewage sludge amended-soils

Untreated sludge from small-scale on-site domestic wastewater treatment systems (septic tanks) was spiked with 20, 60 and 100 nm silver nanoparticles (Ag-NPs) to investigate Ag-NP behaviour in these systems that are widely distributed in rural areas. In addition, the release of Ag-NPs from a previously spiked clay-rich loam reference soil (LUFA 2.4) was evaluated, in the presence and absence of untreated sludge, to simulate the common practice of sludge disposal by spreading on agricultural land. Single particle ICP-MS was used to determine Ag-NP size distribution and the results were compared with total Ag (Ag-NP and ionic) measured in acid digested samples. As documented previously for large municipal scale wastewater treatment plants, Ag-NPs are found to be overwhelmingly (~98%) retained in the sludge in these small-scale systems. The Ag-NP retention efficiency on the LUFA reference soil amended with sludge is approximately 10 times greater than that of LUFA soil alone (in the absence of sludge). For soil spiked with 60 nm Ag-NPs, the calculated average diameter of Ag-NPs in the supernatant, after 24 h was 45 ± 3 nm (dissolution rate 7.2E−06 mol/m2·h for 60 nm Ag-NP), smaller than that of supernatant from the combined sludge/soil system (52 ± 2 nm), indicating lower Ag-NP dissolution rates in the sludge-amended soil. This study provides new information about the leachability of Ag-NPs from septic tank sludge and suggests that the effluent and sludge from septic tanks are potential sources of both nano- and dissolved ionic-Ag to environmental waters.

BIOCHAR AS AN ECO-ADDITION IN WASTEWATER AND WASTEWATER SLUDGE TREATMENT PROCESSES IN NON-URBANIZED AREAS

Especially in non-urbanized areas there is a need to use various waste products, e.g. from agriculture, households, etc. New products that are created in a simple way should be able to be used many times without the use of complicated and expensive technology.
 This article presents the potential of biochar used in wastewater treatment processes and sludge management in small installations - for the maximum maintained number of users equal to 50. The possibilities of two substances used in sewage management processes, such as char and biochar will be presented. These substances, produced from pyrolysis, are stable carbon-rich compounds which have various beneficial applications like soil conditioning, remediation and wastewater treatment. In particular, biochar originating from wastewater sludge pyrolysis, possible to be generated at the place of formation, was taken into account. In addition, ways to increase the reliability of the treatment plant with biochar based filters are described.
 Attention was paid to the various applications of biochar and its effectiveness in the above-mentioned processes, for various pollutants, typical ones and for more demanding installations (high-efficient treatment), among others:
 - study of biochar filters as a replacement or complement for mineral filters for removal of pharmaceutically active compounds from wastewater in onsite wastewater treatment plants (OWTP’s). Results from the works of biodegradation, adsorption and a combination of these processes on the removal of pharmaceutically active compounds wastewater in biochar filters will be presented. worked under typical for onsite wastewater treatment plants conditions e.g. infiltration beds. Various variants of tested installations will be presented (with different forms of biochar and on various medium)
 - study of char and biochar use for different heavy metals after being filtered through biochar and char filters.
 - study of different forms of biochar, derived from natural, easily accessible sources, which can be easily reused in the environment as a fertilizer or biocompost, for example from: sludge from onsite wastewater treatment plants, Miscanthus, rice husks and wood chips, which differ in composition, porosity, active surface, sorption potential, and finally in the effectiveness of retaining various contamination.

High-Strength Domestic Wastewater Treatment and Reuse with Onsite Passive Methods

This paper describes the preliminary monitoring results of an onsite pilot wastewater treatment plant consisting of a septic tank, an anaerobic up-flow filter, and a horizontal subsurface flow wetland system planted with Agapanthus africanus. The system was designed to treat heavily polluted domestic wastewater produced in a research and development (R&D) center, reaching additional goals of zero energy consumption and eliminating the use of chemical additives. First water quality data shows that organic load in the treated sewage were removed achieving more than 95% efficiency. Nutrients were removed by almost 50%, and fecal and total coliform counts decreased by 99.96%. The results were compared to official Mexican regulations for wastewater discharged into lakes and reservoirs complied with all of them except for nutrients. In this pilot project, the resulting treated wastewater was directly reused for watering the green areas of the R&D center. The result was that the excess of nutrients improved the quality of the grass, avoiding the use of synthetic fertilizers, and created a wetland habitat for small wildlife species living in the area.

Properties of Antibiotic-Resistant Bacteria Isolated from Onsite Wastewater Treatment Plant in Relation to Biofilm Formation

The aim of the present study was to determine some properties of antibiotic-resistant bacterial strains isolated from onsite wastewater technology in relation to biofilm formation, e.g., autoaggregation and motility. Additionally, biosurfactant production by the isolates was also evaluated. The ability of selected strains to develop a biofilm was assessed by using the crystal violet method, which allows to indirectly quantify the attached bacterial biomass (live, dead cells, and polysaccharides as well). Obtained results showed that 19 of the analyzed strains were able to produce biofilm after 72 h of incubation. The low values of surface tension in the range between 28 and 36 mN/m were observed in the bacteria, which are not able to produce biofilm or be classified as weak biofilm producers. Among biofilm-forming strains the highest autoaggregation index was observed for Mycobacterium brumae and Bacillus alcalophilus. Noteworthy, that some strains capable of biofilm formation showed no aggregation abilities or were characterized by low autoaggregative properties. The results of visual autoaggregation assay showed no visible flocs after given time of incubation. The results from motility test demonstrated that most of the analyzed strains were motile. Noteworthy, that up to now literature data about physiology, biofilm formation, and autoaggregative capabilities of bacteria isolated from onsite wastewater technology are very limited and this paper gives the information on the antibiotic-resistant bacteria with ability to form biofilm. Thus, the present study points to develop novel bioinocula in antibiotic degradation and to reach novel biofilm-dispersing agents produced by various bacteria that can be used as disinfectants or surface-coating agents to prevent microbial surface colonization and biofilm development.

Planning the optimal solution for wastewater management in rural areas - case study

Water management and associated wastewater management is an inseparable element of life and development of modern societies. Collection and treatment of wastewater has a significant impact on the environment and economy, both at the local and global level. It is therefore necessary to proceed to activities that ensure proper wastewater management, especially in rural and low-density areas, where it is necessary to search for optimal solutions with regard to sewage systems, including wastewater treatment plants. One of the solution for wastewater treatment from houses without access to sewerage collection system is the construction of on-site wastewater treatment plants. Construction of on-site wastewater treatment plant poses a number of challenges for municipalities and potential investors and has been discussed by many. Aim of this paper is to draw the current status and perspectives of on-site wastewater treatment systems in Poland, with focus on selected case study from rural areas. The paper presents a way to solve the problem of wastewater management in the municipality of Pietrowice Wielkie using local biological wastewater treatment plants. The article presents technological, technical and economical aspects of the above-mentioned solutions and analysis of the advantages and disadvantages of the system proposed by the municipality.

Water budget analysis and management for Bangkok Metropolis, Thailand.

The water budget of the Bangkok Metropolis system was analyzed using a material flow analysis model. Total imported flows into the system were 80,080 million m3 per year (Mm3 y-1) including inflows from the Chao Phraya and Mae Klong rivers and rainwater. Total exported flows out of the system were 78,528 Mm3 y-1 including outflow into the lower Chao Phraya River and tap water (TW) distributed to suburbs. Total rates of stock exchange (1,552 Mm3 y-1) were found in the processes of water recycling, TW distribution, domestic use, swine farming, aquaculture, and paddy fields. Only 21% of the total amount of wastewater (1,255 Mm3 y-1) was collected, with insufficient treatment capacity of about 415 Mm3 y-1. Domestic and business (industrial and commercial sectors) areas were major point sources, whereas paddy fields were a major non-point source of wastewater. To manage Bangkok's water budget, critical measures have to be considered. Wastewater treatment capacity and efficiency of wastewater collection should be improved. On-site wastewater treatment plants for residential areas should be installed. Urban planning and land use zoning are suggested to control land use activities. Green technology should be supported to reduce wastewater from farming.

Removal of bacterial cells, antibiotic resistance genes and integrase genes by on-site hospital wastewater treatment plants: surveillance of treated hospital effluent quality

This study aims to evaluate the removal efficiency of microbial contaminants by wastewater treatment plants (WWTPs) operated on-site of two hospitals.

Microbial Community Profiles in Wastewaters from Onsite Wastewater Treatment Systems Technology.

The aim of the study was to determine the potential of community-level physiological profiles (CLPPs) methodology as an assay for characterization of the metabolic diversity of wastewater samples and to link the metabolic diversity patterns to efficiency of select onsite biological wastewater facilities. Metabolic fingerprints obtained from the selected samples were used to understand functional diversity implied by the carbon substrate shifts. Three different biological facilities of onsite wastewater treatment were evaluated: fixed bed reactor (technology A), trickling filter/biofilter system (technology B), and aerated filter system (the fluidized bed reactor, technology C). High similarities of the microbial community functional structures were found among the samples from the three onsite wastewater treatment plants (WWTPs), as shown by the diversity indices. Principal components analysis (PCA) showed that the diversity and CLPPs of microbial communities depended on the working efficiency of the wastewater treatment technologies. This study provided an overall picture of microbial community functional structures of investigated samples in WWTPs and discerned the linkages between microbial communities and technologies of onsite WWTPs used. The results obtained confirmed that metabolic profiles could be used to monitor treatment processes as valuable biological indicators of onsite wastewater treatment technologies efficiency. This is the first step toward understanding relations of technology types with microbial community patterns in raw and treated wastewaters.