Multi-soil-layering System Research Articles

Innovative approaches for Microcystin removal: Bacterioplankton biodegradation and multi-soil-layering system performance assessment

Microcystins (MCs) pose a significant threat to human health and the environment due to their persistence and toxicity as potent cyanobacterial toxins. Effective biodegradation strategies are required for their removal and detoxification. In this study, bacterioplankton were isolated from eutrophic reservoir water used for crop irrigation and tested for their ability to degrade MCs. These bacteria are hydrologically transported from the contaminated reservoir to downstream farms where they are able to grow under the favorable conditions provided by a multi-soil-layering (MSL) system, a low-cost and locally applicable ecotechnology for the removal and detoxification of MCs. These bacteria enhance the ability of the MSL to remove MCs by forming biofilms within the MSL system. The bacterial strains were then sequenced and their partial 16S rRNA was compared to the reference strains in the NCBI database. The effectiveness of the MSL system in the removal of MCs from water was evaluated. The MSL utilizes a layered soil matrix that promotes microbial growth and physicochemical interactions that enable the removal of various contaminants. The mechanisms of MC removal in the MSL were evaluated by studying the physicochemical properties of the system substrate before and after treatment using X-ray fluorescence, zeta potential, and scanning electron microscopy (SEM) analyses. The microbial functional groups, including ammonifying and denitrifying bacteria, were also investigated in the MSL soil matrices before and after treatment. The results showed that seven bacterial strains exhibited high MC degradation capabilities, with MC degradation performance exceeding 97%. These isolated bacterial strains had a nucleotide identity score of 100% and an E value of 0.0 compared to reference strains. The MSL showed a 99% removal rate for MC-LR and MC-YR, as well as significant reductions in other pollutants, including COD (60%), BOD5 (60%), chlorophyll-a (96%), pheophytin (70%), organic nitrogen (80%), and nitrites (90%). After treatment, there was a statistically significant increase in the total bacterial count, as well as ammonifying and denitrifying bacteria, in the MSL soil matrices compared to their state before treatment. SEM analyses revealed the formation of dense biofilm microbiota, indicating additional biological processes besides adsorption for MC reduction. Overall, the MSL provides a low-cost alternative for the removal of MCs and cyanobacteria with minimal resource requirements and maintenance. It offers a promising solution for mitigating toxic cyanobacterial blooms, ensuring safe agricultural water reuse.

Disentangling microbial coupled fillers mechanisms for the permeable layer optimization process in multi-soil-layering systems

The multi-soil-layering (MSL) systems is an emerging solution for environmentally-friendly and cost-effective treatment of decentralized rural domestic wastewater. However, the role of the seemingly simple permeable layer has been overlooked, potentially holding the breakthroughs or directions to addressing suboptimal nitrogen removal performance in MSL systems. In this paper, the mechanism among diverse substrates (zeolite, green zeolite and biological ceramsite) coupled microorganisms in different systems (activated bacterial powder and activated sludge) for rural domestic wastewater purification was investigated. The removal efficiencies performed by zeolite coupled with microorganisms within 3 days were 93.8% for COD, 97.1% for TP, and 98.8% for NH4+-N. Notably, activated sludge showed better nitrification and comprehensive performance than specialized nitrifying bacteria powder. Zeolite attained an impressive 89.4% NH4+-N desorption efficiency, with a substantive fraction of NH4+-N manifesting as exchanged ammonium. High-throughput 16S rRNA gene sequencing revealed that aerobic and parthenogenetic anaerobic bacteria dominated the reactor, with anaerobic bacteria conspicuously absent. And the heterotrophic nitrification-aerobic denitrification (HN-AD) process was significant, with the presence of denitrifying phosphorus-accumulating organisms (DPAOs) for simultaneous nitrogen and phosphorus removal. This study not only raises awareness about the importance of the permeable layer and enhances comprehension of the HN-AD mechanism in MSL systems, but also provides valuable insights for optimizing MSL system construction, operation, and rural domestic wastewater treatment.

Efficiency of a new hybrid multi-soil-layering eco-friendly technology for removing pollutants from domestic wastewater under an arid climate

The goal of this research is to assess and track the efficacy of hybrid multi-soil-layering (MSL) plant in treating domestic wastewater for reuse in landscape irrigation. The investigated wastewater treatment plant is composed of a solar septic tank followed by a vertical flow MSL (VF-MSL) unit in series with a subsurface horizontal flow MSL (HSSF-MSL) unit. Wastewater samples were taken bimonthly from the plant's influent and effluent, respectively. The two-stage MSL units are composed of gravel layers alternated with soil-based layers, which are arranged in brick-like patterns, although they are operated under an HLR of 250 L m−2 day−1, which corresponds to 125 g COD/m2/d, 52 g TN/m2/d, and 2.70 g TP/m2/d. The mean removal efficiency was 75 %, 42 %, 67 %, and 47 %, respectively, for TSS, COD, NH4+, and TP for the VF-MSL system. Moreover, the VF-MSL combined with the HSSF-MSL system resulted in significant nitrogen removal as well as a significant reduction (p < 0.05) in organic matter and phosphorus with an abatement of 97 %, 79 %, 76 %, and 27 %, respectively, for TSS, COD, TP, and TN. For fecal bacteria indicators, the hybrid MSL system achieved high log removals, reaching 2.88 log units during two years of monitoring. Principal component analysis (PCA) was done on the positive correlation between COD, NH4+, TP removal, and summer seasons. Nonetheless, the winter season significantly influenced TN removal in the MSL system. The investigated hybrid multi-soil-layering plant has been shown to be effective in terms of water quality for the irrigation of green spaces in urban areas.

Domestic Wastewater Treatment with Multi Soil Layering Method with Variations of Hydraulic Loading Rate (HLT) And Organic Materials at Anaerobic Conditions

Domestic wastewater is the largest producer of wastewater in Indonesia which comes from the remnants of household activities. Hazardous substances such as Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Oil and Fat contained in wastewater can cause health problems for humans. In this study, domestic waste treatment was carried out using the Multi Soil Layering (MSL) method. The MSL system is a wastewater treatment method that utilizes the ability of soil as the main medium and several other media such as zeolite, gravel, charcoal, and sawdust which are formed in a multilevel brick pattern. The independent variables are the variation of soil mixture with sawdust (M1) and soil mixture with charcoal (M2) and also variations of Hydraulic Loading Rate namely HLR 500 L/m2.day (H1), 750 L/m2.day (H2), 1000 L/m2.day (H3). The characteristics of domestic wastewater include pH 6, BOD 236 mg/L, COD 514 mg/L, TSS 114 mg/L, Oil and Fat 8200 mg/L. The results showed that the best variation in the removal of pollutant levels was a mixture of soil with charcoal (M2) and HLR 500 L/m2.day (H1), with the average efficiency in reducing BOD, COD, TSS, Oil & Fat levels, respectively. 86.39%, 78.29%, 86.56% and 79.60%.

المرشحات المتداخلة: تقنية بيئية منخفضة التكلفة لمعالجة المياه العادمة اللامركزية وإعادة استخدامها

الملخص صُمّم نظام المرشحات المتداخلة بوصفه مرشحاً حيوياً قائماً على قدرات التربة الفيزيوكيميائية والأحيائية لمعالجة ملوثات المياه العادمة، ويتميز من باقي الأنظمة الطبيعية المماثلة بحاجات أقل إلى الطاقة والمساحة والصيانة، وإمكانية إعادة استعمال المياه المعالجة في الموقع نفسه. يتكون النظام من طبقتين متباينتين من حيث المواد المستخدمة والمسامية: طبقات خليط التربة والطبقات النفاذة، المرصوصة في شكل يشبه اللبنات؛ حيث مكّن هذا التصميم البارع من تقليص احتمالية انسداد النظام، وزيادة قدرته على تلقّي أحجام كبرى من المياه العادمة، مع ازدواجية الظروف الهوائية واللاهوائية داخله؛ الشيء الذي أكسبه قدرات معالجة متقدمة لمختلف الملوثات بمختلف أنواع المياه العادمة اللامركزية. يهدف هذا البحث إلى التعريف بنظام المرشحات المتداخلة بوصفه تقنية بيئية صاعدة، حيث يلخص مبدأ عمله، وأدوار المواد المكونة له، وآليات معالجة مختلف الملوثات. ويستعرض نتائج بعض الاستخدامات الموفقة لهذا النظام عبر عدد من دول العالم، ونتائج دراسة التكلفة المنجزة التي أكدت انخفاض تكلفة بنائه، والتي لا تتعدى 80 دولاراً أمريكياً لمعالجة متر مكعب من المياه العادمة في اليوم لمدة 20 سنة متواصلة من الاستخدام. وأخيراً، يُظهر البحث، بناء على مقارنات بأنظمة مماثلة، مكامن القوة التي تجعل من هذا النظام بديلاً مستقبلياً ومستداماً للدول النامية كدول أفريقيا.

Removal Efficiency of Chemical Oxygen Demand on Greywater using Multi Soil Layering (MSL) Technology

Greywater is household waste sourced from kitchens and bathrooms, except for toilets. Around 58%-85% of greywater can be generated from the total volume of household wastewater per house. It is necessary to treat wastewater before it is discharged into water bodies to prevent the adverse effects of contaminants on the environment and human health while reducing the demand for clean water. However, due to environmentally friendly, socially sustainable, and economical treatment costs, considering that greywater is produced every day and continuously, Multi Soil Layering (MSL) technology can be an alternative to remove contaminants in water. Thus, this study aims to determine the migration of COD in greywater using MSL technology. Other parameters tested were pH and temperature by taking samples of wastewater in residential areas of Semarang City. In this study, there are two stages, namely the preliminary stage and the running stage. The MSL system will use three reactors with andosol soil, apus bamboo, and coconut shell activated charcoal as mixed soil blocks (SMB). Reactor A (activated charcoal and andosol soil), reactor B (bamboo apus and andosol soil), reactor C (andosol soil, bamboo apus, activated charcoal). The results of domestic wastewater treatment using the MSL method in each of the three reactors could remove COD by 75%, 74%, and 76%. Reactor C obtained the highest COD removal efficiency compared to other reactors.

Comparing natural red soil and irons for removal of phosphorus from wastewater using the multi-soil-layering system and its economic analysis

The study uses an emerging soil treatment technology, the Multi-Soil Layering System (MSL), which is composed of the zeolite permeability layers (PL) and the soil mixture block layers (SMB). The experimental results show that the SMBs with iron particle (SMB-I) removed more than 83% of the total phosphorus (P) pollution in the water, and the outflow sewage concentration is 9.6 mg/L. In contrast, the SMBs with red clay (SMB-R) has 23% removal rate, and the outflow sewage concentration is 46.45 mg/L. Only 0.013 mg/L Fe concentration was detected in the SMB-R system and release of Fe from red soil is hardly achieved under neutral water environment. The SMB-R and SMB-I systems reduced 108.89 mg/g and 20.93 mg/g respectively and the SMB-R had higher removal efficiency of P per gram released Fe. The chromaticity problem of the effluent water in the SMB-I is up to 225 platinum cobalt, and that of the SMB-R is 172 platinum cobalt. Adding 10 g oyster shell (slice-only) and/or 0.65 g polyglutamic acid have effectively removed up to 99% 25-mg/L Fe in the effluent water; the chromaticity problem caused by Fe effluent was successfully solved. Furthermore, the iron particle has the highest unit cost among the materials in the SMBs (US$1.47/kg in lab and US$0.12/kg in field). Removal of 1 mg/L TP in the MSL system costs US$0.036 (by lab) in terms of removal TP rate in the laboratory was 83% and is economically feasible in field development.

Removal of ammonia in domestic wastewater by using multi soil layering

Domestic wastewater is the primary source of river pollution. Every human activity in the house must produce waste. Domestic wastewater from the kitchen, bathing, and washing activities contains organic pollutants. The parameter tested was ammonia. In this study, Multi Soil Layering (MSL) was used as a processing method. This treatment serves to reduce ammonia levels in wastewater. This study aims to determine the removal of ammonia in greywater using the Multi Soil Layering System. Wastewater samples were taken in a residential area of Semarang. In this study, there are 2 stages, namely the preparation and implementation stages. In the seeding and acclimatization process, a batch reactor was used for 14-24 days running. The next stage is the process of running for 20 days with intermittent flow. Soil Mixture Box (SMB) is a mixture of andosol soil and activated charcoal (reactor A), andosol soil and apus bamboo (reactor B), and andosol soil, activated charcoal, and apus bamboo (reactor C). The results of domestic wastewater treatment using the MSL method respectively in the three reactors can remove ammonia by 49%, 51%, and 52%.

The efficiency of biological oxygen demand removal in domestic wastewater treatment using multi soil layering

Domestic wastewater from the kitchen, bathing, and washing activities contains organic pollutants. The parameter tested was Biological Oxygen Demand (BOD). In this study, Multi Soil Layering (MSL) methods have been used as a processing method. This treatment serves to reduce ammonia levels in wastewater. This study aims to determine the removal of BOD in gray water using the Multi Soil Layering System. Wastewater samples were taken in a residential area of Semarang. In this study, there are 2 stages, namely the preparation and implementation stages. In the seeding and acclimatization process, batch reactors are used for 14-24 days. The next stage is the process of running for 20 days with intermittent flow. Soil Mixture Box (SMB) is a mixture of andosol soil and activated charcoal (reactor A), andosol soil and apus bamboo (reactor B), and andosol soil, activated charcoal and apus bamboo (reactor C). The results of domestic wastewater treatment using the MSL method respectively in the three reactors can remove BOD by 26%, 25%, and 29%.

Dissolved organic matter characteristics and removal of trace organic contaminants in a multi-soil-layering system

This study investigated the role of soil mixture blocks (SMBs) in the removal of trace organic contaminants and the changes in dissolved organic matter characteristics in a laboratory-scale multi-soil-layering (MSL) system. The experimental setup included three soil-based water treatment systems, namely MSL, MSL without SMBs (zeolite/slag), and a sand filter. The effect of SMBs in the removal of dissolved organic matter in MSL was not significant, but the use of zeolite/slag in MSL enhanced the removal of humic substances and building blocks. Through membrane fractionation, the size distribution of dissolved organic matter in the MSL system was not changed, and the majority of the dissolved organic matter is below 1 kDa. Ten pharmaceutically active compounds and three endocrine-disrupting compounds were used to investigate the removal of selected trace organic contaminants in the MSL system, zeolite/slag, and sand filter. The attenuation of pentoxifylline, caffeine, 17α-ethinylestradiol, estrone, and 17β-estradiol in the MSL system was similar to that for zeolite/slag, and the removal efficiency was greater than 80%. However, pentoxifylline, caffeine, 17α-ethinylestradiol, estrone, and 17β-estradiol exhibited relatively low removal efficiencies in the sand filter compared to those in the MSL system and zeolite/slag. Results from this study provide insight into the removal of selected trace organic contaminants in MSL system, which could be considered as one of the series of barriers to remove trace organic contaminants in wastewater.

Neural network and cubist algorithms to predict fecal coliform content in treated wastewater by multi-soil-layering system for potential reuse.

This study aims to find the most accurate machine learning algorithms as compared to linear regression for prediction of fecal coliform (FC) concentration in the effluent of a multi-soil-layering (MSL) system and to identify the input variables affecting FC removal from domestic wastewater. The effluent quality of two different designs of the MSL system was evaluated and compared for several parameters for potential reuse in agriculture. The first system consisted of a single-stage MSL (MSL-SS), and the second system consisted of a two-stage MSL (MSL-TS). The concentration of FC in the effluent of the MSL-TS system was estimated by three machine learning algorithms: artificial neural network (ANN), Cubist, and multiple linear regression (MLR). The accuracy of the models was measured by comparing the real and predicted values. Significant (p<.001) improvements were noted for the removal of pollutants by the MSL-TS system compared with the MSL-SS system. Overall, the water quality parameters investigated complied with FAO irrigation standards. The predictive performance of the models has been compared and evaluated using several metrics. The results revealed that the ANN model yielded a superior predictive performance (R2 =.953), followed by the Cubist model (R2 =.946) and the MLR technique (R2 =.481). Based on the accurate model (ANN), the degree of influence of each predictor was investigated, and the results show that total suspended solids and pH have proved to be more useful for predicting FC concentrations.

Predicting the concentration of total coliforms in treated rural domestic wastewater by multi-soil-layering (MSL) technology using artificial neural networks

Many indicators are involved in monitoring water quality. For instance, the fecal indicator bacteria are extremely important to detect the water quality. For this purpose, to better predict the total coliforms at the outlet of a Multi-Soil-Layering (MSL) system designed to treat domestic wastewater in rural areas, a neural network model has been developed and compared with linear regression model. The data was collected from the raw and treated wastewater of a three MSL systems during a one-year period in rural village, in Al-Haouz Province, Morocco. Fifteen physicochemical and bacteriological variables have undergone feature selection to select the best ones for predicting the total coliforms concentration in the effluent of MSL system. Furthermore, 80% of the available dataset were used to train and optimize the neural model using repeated cross validation technique. The remaining part (20%) was used to test the developed model. The neural network indicated excellent results compared to the linear regression. The optimal model was a neural network with one hidden layer and 11 neurons, where the R2 was about 97%. The importance analysis of each predictor was established, and it was found that pH and total suspended solids had the greatest influence on the total coliforms removal.

Nouveau design solar septic tank: Reinvented toilet technology for sanitation 4.0.

The up-flow solar septic tank (UTST) and multi-soil layering (MSL) system has been developed and proposed as “Nouveau Design Solar Septic Tank”. The objective of this study was to verify functionality of the integrated UTST and MSL system for treatment of toilet wastewater (or black water) under actual conditions over a year at the Asian Institute of Technology campus, Pathumthani province, central Thailand. During the operation period which involved fluctuating flow rates, ambient temperatures and black water characteristics, the UTST unit yielded satisfactory performance with the average treatment efficiencies of 9210% for total chemical oxygen demand (TCOD), 7910% for soluble chemical oxygen demand (SCOD), 939% for total 5-days biochemical oxygen demand (TBOD) and 9012% for soluble 5-days biochemical oxygen demand (SBOD), respectively, while the MSL unit could remove 95 3%, and 88 15% of total kjeldahl nitrogen (TKN) and total phosphorus (TP), respectively. The effluent TCOD, TBOD, TKN, nitrite (NO2-N), nitrate (NO3-N), ammonia (NH3) and TP concentrations of the integrated UTST and MSL system were 3927,827,55 mg/L, 22,3924,89,25 and 11 mg/L, respectively, meeting the ISO requirements. The removal efficiencies of TCOD, SCOD, TBOD and SBOD exhibited positive correlation with the ratios of TBOD/TKN, TBOD/SBOD and TBOD/TP. With high treatment efficiencies and effluent quality meeting the ISO requirements, the nouveau design solar septic tank has been demonstrated as an innovative technology toward the sanitation 4.0 concept and the Sustainable Development Goal no. 6 (SDG6).

Efficiency of Multi Soil Layering (MSL) System in A Household Scale of Wastewater Treatment Using Environmental Friendly Materials

Most community settlements in Indonesia do not have a household scale of a wastewater treatment plant. Fatal impacts on the environment and human health can occur at any time, including (a) causing environmental damage (disaster), (b) damaging beauty/aesthetics for the scenery will be unpleasant and foul-smelling, (c) polluting water bodies, and (d ) endangering health. The purpose of this study is to optimize the Multi Soil Layering (MSL) System to treat domestic wastewater (greywater) using environmentally friendly materials that are available in Indonesia. The research method used the MSL system with the first variation using a batch system with Hydraulic retention time (HRT) for 24 hours and the second variation using an intermittent system with 3, 6, 9 hours HRT. The results showed that the MSL system was able to eliminate COD well. The highest COD removal efficiency was 93.44% at 9 hours HRT, but the effluent quality did not meet the required quality standards. The development of MSL systems that produces an effluent quality that meets the quality standards needs to be studied further.

A biophysiological perspective on enhanced nitrate removal from decentralized domestic sewage using gravitational-flow multi-soil-layering systems

Multi-soil-layering (MSL) system with brick-wall pattern structure and gravitational flow can be used for decentralized rural domestic sewage treatment. The capability of soil for contaminant removal is maximized within soil mixture blocks (SMBs). However, the performance of removing nitrate was still not ideal during operation. To improve its performance in MSL system, the relationship between biophysiological characteristics of denitrifying species and operating conditions was studied. Microbial species diversity of activated sludge and soil samples were analyzed. The significant effects of independent factors and their interactions on microbial species diversity and denitrifying species abundance were revealed on the basis of factorial analysis. The results indicated activated sludge in SMBs played a key role in increasing the richness of denitrifying species in MSL system. Slow-release poly (butylene succinate) (PBS) had the most dominant positive effect on increasing denitrifying species abundance. Submersion had significantly positive effect on species richness in SMBs. These three factors, including activated sludge, PBS in SMBs, and submersion condition had different significant effects on microbial responses. They were favorable for denitrification and ensuring a better removal efficiency of nitrate and total nitrogen. The porous zeolites were served as the habitats for most of aerobic bacteria to form biofilms, which could promote the oxygen consumption in both sewage and system to improve denitrification in SMBs. The results could help on the enhancement of denitrification in MSL system from biophysiological insights. It can provide a sound strategy for using MSL system with great performance on contaminant removal.

PENJERNIHAN AIR SUMUR MENUJU AIR LAYAK MINUM DENGAN METODA LAPISAN MULTI MEDIA ( LMM )

The Multi Soil layering (MSL) system is a liquid waste treatment method with the use of soil as the main medium and the organic material formed in brick and arranged in layers with a homogeneous zeolite layer. The MSL system is made of acrylic (50 x 15 x 50) cm containing a brick (4 x 9 x 15) cm and (4 x 5 x 15) cm of volcanic soil mixture as the main medium mixed with charcoal, rice husk, and iron powder (70 : 10 : 10 : 5)%, permiable layer is used zeolite (2-3) mm. The sample came from the well water of one of villager at Jati, Padang. Efficiency of SML system for aeration process on turbidity parameter with flow rate variation of 2, 4, 6, 8 mL/min reach 99,8 %, for non aeration process efficiency of turbidity decrease 88,14 %. While for the flow rate of 10, 20, 40, 80 mL/min, the efficiency of decrease for aeration at parameters Mn 66,44 %, nitrite 59,74 %, nitrate 58,34 %, turbidity 54,63 %, while in non aeration efficiency decrease turbidity reach 44,04 %, Mn 47,26 %, nitrite 49,74 %, nitrate 45,57 %. Of all efficiency values decreasing all parameters already complied drinking water quality standard according to Permenkes RI No. 492/Menkes/Per/IV/2010.

Evaluation of Long-Term Wastewater Treatment Performances in Multi-Soil-Layering Systems in Small Rural Communities

Multi-soil-layering (MSL) wastewater treatment systems consist of soil units (soil mixture blocks, SMB) arranged in a brick-like pattern surrounded by permeable layers of zeolite or alternating particles of homogeneous sizes that allow for a high hydraulic loading rate. This study evaluated the performances of MSL systems that have been operating for 17 to 20 years in small rural communities. Even though 20 years had passed since this system was installed, high organic matter treatment performance continued. Nitrogen removal was higher than with conventional soil systems. Two of the MSL systems continued to show high phosphorus removal performances, whereas in the third system, the adsorbing capacity was relatively low, requiring further investigation. Treatment performances were largely dependent upon the structure of the MSL systems. It appeared that improving the structure to enhance the contact efficiency between the wastewater and the soil in SMB was important for enhancing treatment performances. The combined use of existing wastewater treatment systems with the MSL system was effective for preventing environmental pollution over a long period.

Experimental Investigation of Treatment of Domestic Wastewater Using Multi Soil Layering (MSL) System

Soil has been used for the treatment of wastewater from long time ago. Domestic wastewater treatment and disposal is the serious problem our country is facing nowadays. If not treated it further pollutes the rivers. In villages or rural areas where centralized wastewater treatment is not possible because of the scattered houses, a decentralized treatment unit needs to be installed. Multi Soil Layering system is such a decentralized treatment used for the treatment of domestic wastewater. The main objective of this study is to investigate the experimental setup of Multi Soil layering system for the treatment of domestic wastewater. The pre-fabricated acrylic material model of dimension 50cm (L) x 20cm (W) x 60cm (D) was used for the experimental analysis. The potential of the MSL for removal of pollutants from wastewater by changing the operating conditions like flow rate, aeration and non aeration condition was studied. The MSL system proved to be efficient for treatment of domestic wastewater. The study revealed that the flow rate of 0.2 m3/m2/day with aeration condition was efficient for treating domestic wastewater by Multi Soil Layering System. For Flow rate of 0.2 m3/m2/day, the average inlet and outlet ph was observed pH 6.75 and 7.59. The percent removal was as follows: BOD: 87.63%, COD: 87.73%, TSS: 77.12% and TP: 95.45%.

Biophysiological and factorial analyses in the treatment of rural domestic wastewater using multi-soil-layering systems

Multi-soil-layering (MSL) system was developed as an attractive alternative to traditional land-based treatment techniques. Within MSL system, the environmental cleanup capability of soil is maximized, while the soil microbial communities may also change during operation. This study aimed to reveal the nature of biophysiological changes in MSL systems during operation. The species diversity in soil mixture blocks was analyzed using Illumina HiSeq sequencing of the 16S rRNA gene. The interactive effects of operating factors on species richness, community diversity and bacteria abundance correlated with COD, N and P removal were revealed through factorial analysis. The results indicated the main factors, aeration, bottom submersion and microbial amendment, had different significant effects on microbial responses. The surface area and porosity of zeolites in permeable layers decreased due to the absorption of extracellular polymeric substances. The findings were applied for the design and building of a full-size MSL system in field and satisfied removal efficiency was achieved. The results of this study can help better understand the mechanisms of pollutant reduction within MSL systems from microbial insights. It will have important implications for developing appropriate strategies for operating MSL systems with high efficiency and less risks.

Wastewater Treatment Plant Performance Inside Multi-Soil-Layering System

Wastewater effluent disposal is a challenge in Moroccan rural area. Wastewater treatment is the only suitable solution to overcome these environmental constraints. Technology such as Multi-Soil-Layering (MSL) system is one of the most appropriate solution for the treatment of wastewater for small communities in rural areas. The MSL system overcomes many of the deficiencies of conventional soil treatment systems such as large land requirement clogging and low Hydraulic Loading Rate (HLR). The MSL systems are composed of Soil Mixture Blocks (SMB) arranged in a brick-like pattern and surrounded by Permeable Layers (PL). To investigate the efficiency of MSL systems in relation to HLR differences and the fluctuations in the wastewater contamination levels, three MSL pilot plants were alimented continuously by domestic wastewater, were constructed in three 36×30×65 cm plastic boxes, with different HLR of 250, 500 and 1000 l/m2/day. The main removal rates of Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) were higher at higher HLR. However, the kinetic rate constant of the MSL process implemented under Moroccan conditions is 130 d-1 at 25°C.