Low Pollution Load Research Articles

Eco-toxic Risk Assessment of microplastics in water and sediment across Nigeria Offshore, Gulf of Guinea.

Globally, the environmental impacts of microplastics (MPs) as emerging pollutants have drawn a lot of attention. This study aimed to assess the distribution and associated potential ecotoxic risk of MPs in the water and sediment of Nigeria's offshore waters. Water and sediment samples were collected from sixteen (16) stations in October 2023 and analysed using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and stereomicroscopy. For physical characterization, the composition of MPs in sediment and water was 73 particles/kg and 48 particles/L, respectively, while the ATR-FTIR composition at the Eastern Zone (EZ) was 705 particles/L and 1033 particles/kg, the Central Zone (CZ) was 212 particles/L and 338 particles/kg, and the Western Zone (WZ) was 223 particles/L and 218 particles/kg. The identified MPs shapes were filaments, plastic films, fibre, and microbeads. Polychloroprene (CR) (18.10% and 16.86%) at EZ and CZ and polyvinyl alcohol (PVA) (20.64%) at WZ were most abundant in sediment, respectively. In comparison, PVA (22.3%, 22.2%, and 21.08%) was most abundant across EZ, CZ, and WZ in water. The polymer-based plastic contamination factors (ppCf) and pollution load index (pPLI) showed low contamination and pollution load, and the polymer risk index (pRi) showed medium and low risk in water and sediment, respectively. The polymer ecological risks index (pERI) showed a high-risk level (pERI: 1,001-10,000) in water and sediment across the EZ, CZ, and WZ of the Nigerian offshore waters. In marine environments, an extensive environmental monitoring program and trend forecasting for microplastics are crucial. This study will provide theoretical and technical support for developing efficient legislation or policy on the prevention and control of plastic pollution.

Health risk assessment of the concentrations of trace metals in some fruit juices from markets in Ghana

The study aimed to assess the risk exposure of processed fruit juices sold in Ghana by analyzing the concentrations of Cd, As, Ni, Hg, Cr and Pb. 27 processed fruit products were sampled from three markets and categorized based on packaging type. Heavy metals were quantified using Microwave Plasma Atomic Emission Spectroscopy (MPA-ES) The results showed that Cd was not detected in any of the samples, while the average measured concentrations of Ni, Pb, As, Cr and Hg were 0.186, 0.201, 0.299, 0.839 and 0.062 mg/L, respectively. Although Cr levels were within acceptable limits in most products, concentrations of Pb, Hg, As and Ni exceeded permissible levels in several samples. On average, canned products had higher metal concentrations than paper packs and bottles. Imported products also showed higher levels than locally processed items. Pollution assessment indicated low pollution load index below 1. Health risk analysis revealed potential non-carcinogenic risks associated with As, Cr and Hg intake, with a hazard index exceeding 1 in over 50 % of products. Cancer risk estimation showed concerning values for Cr in all samples and Pb in some products. toxic elements could pose health hazards to consumers of processed fruit juices sold on Ghanaian markets.

Insights into the seasonal distribution of microplastics and their associated biofilms in the water column of two tropical estuaries

The present study describes the seasonal distribution of microplastics (MPs) and their associated biofilms in the water column of the Netravathi-Gurupura estuary, southwest India. An average abundance of 8.15 (±3.81) particles/l and 1.14 (±0.78) particles/l was observed during the wet and dry seasons, respectively. Fibres, films, and fragments accounted for majority of the microplastics. Polyethylene terephthalate, polyethylene, polyurethane, polyester, polystyrene, and high-density polyethylene were the major polymers. The risk assessment revealed a low Pollution Load Index, but the Polymer Hazard Index showed higher toxicity. Diatoms from nine genera were observed attached to the microplastic samples with Amphora and Navicula spp. reported in both estuaries during both seasons. The considerable diversity of diatoms, along with other microbial groups, in microplastic-associated biofilms in this study, highlights the urgent need to understand the structure and development of microplastic-associated biofilms and their role in the vertical and horizontal transport of microplastics in tropical estuaries.

A novel approach for purifying food waste anaerobic digestate through bio-conditioning dewatering followed by activated sludge process: A case study

Although anaerobic digestion is the mainstream technology for treating food waste (FW), the high pollutant concentration in the resultant food waste anaerobic digestate (FWAD) often poses challenges for the subsequent biochemical treatment such as activated sludge process. In this study, taking a typical FW treatment plant as an example, we analyzed the reasons behind the difficulties in treating FWAD and tested a novel process called as bio-conditioning dewatering followed by activated sludge process (BDAS) to purify FWAD. Results showed that high concentrations of suspended solids (SS) (16439 ± 475 mg/L), chemical oxygen demand (COD) (24642 ± 1301 mg/L), and ammonium nitrogen (NH4+-N) (2641 ± 52 mg/L) were main factors affecting the purification efficiency of FWAD by the conventional activated sludge process. By implementing bio-conditioning dewatering for solid-liquid separation, near 100% of SS and total phosphorus (TP), 90% of COD, 38% of total nitrogen (TN), and 37% of NH4+-N in the digestate could be effectively removed or recovered, consequently generating the transparent filtrate with relatively low pollution load and dry sludge cake (<60% of moisture content). Furthermore, after ammonia stripping and biochemical treatment, the effluent met the relevant discharge standards regulated by China, with the concentrations of COD, TN, NH4+-N, and TP ranging from 151 to 405, 10–56, 0.9–31, and 0.4–0.8 mg/L, respectively. This proposed BDAS approach exhibited stable performance and low operating costs, offering a promising solution to purify FWAD in practical engineering and simultaneously realize resource recovery.

The pollution of microplastics in sediments of the Yangtze River Basin: Occurrence, distribution characteristics, and basin-scale multilevel ecological risk assessment.

Microplastics (MPs) pollution in the Yangtze River Basin (YRB) of China has grown to be a serious issue, yet there is a lack of understanding of the environmental risks of MPs in the sediment of the entire basin. This work revealed the spatial distribution characteristics of MPs in YRB sediments, and it methodically assessed the ecological risks of MPs by taking into consideration their abundance, toxic effects, and polymer types. The results showed a high heterogeneity in the abundance of MPs in YRB sediments, with an average of 611 particles/kg dry weight (DW) sediment. Small-sized MPs (<1mm), fibrous, transparent-colored and polypropylene (PP) accounted for the majority with 71.6%, 68%, 37% and 30.8%, respectively. Correlation analysis indicated significant influences of human activities such as population, industrial structure, and urban wastewater discharge on the abundance and morphological types of MPs in sediments. Based on chronic toxicity data exposed to sediments, a predicted no-effect concentration (PNEC) of 539 particles/kg DW was calculated using the species susceptibility distribution (SSD). Multiple deterministic risk assessment indices indicated that MPs in YRB sediments exhibited primarily low pollution load levels, moderate-to-low potential ecological risk levels, and high levels of polymer pollution. However, probabilistic risk assessment revealed an overall low risk of MPs in YRB sediments. Monte Carlo simulation results demonstrated that polyvinyl chloride (PVC) and polycarbonate (PC) made a great contribution to ecological risk and should be considered as priority control pollutants in MPs. In addition, various assessments showed that the ecological risk of MPs in river sediments was higher than that in lake reservoir sediments. This is the first study to comprehensively assess the ecological risk of MPs in sediments of the YRB, which improves the understanding of the basin-wide occurrence characteristics and environmental risks of MPs in freshwater systems.

Applying water environment capacity to assess the non-point source pollution risks in watersheds

Comprehension of the spatial and temporal characteristics of non-point source (NPS) pollution risk in watersheds is essential for NPS pollution research and scientific management. Although the concept of water functional zones (WFZ) has been considered in the NPS pollution risk assessment process. However, no comprehensive study of the NPS pollution risk has been conducted to effectively protect water quality in watersheds with different water environment capacity. Therefore, this study proposes a new NPS pollution risk assessment method that integrates water functional zoning, receiving water body environmental capacity, and space-time distribution of pollution load for quantifying the impact of pollution discharge from sub-catchment on nearby water body quality. Based on the NPS nutrient loss process modeled by the Soil and Water Assessment Tool (SWAT), this method was used to assess the NPS pollution risk in the Le 'an River Watershed at annual and monthly scales. The results showed that the NPS pollution risk is characterized by seasonal and spatial variability and is influenced clearly by the water environment capacity. High NPS pollution loads are not necessarily high pollution risks. Conversely, a low NPS nutrient pollution load does not represent a low regional risk sensitivity. In addition, NPS risk assessment based on the water environment capacity could also distinguish the differences in risk levels that were masked by similar NPS pollutant loss and the same water function zoning to achieve accurate control of NPS pollution management in watersheds.

RETRACTED: The persistent, bioaccumulative, toxic, and resistance (PBTR) risk assessment framework of antibiotics in the drinking water sources

Antibiotics are emerging pollutants largely considered to have a lower risk based on persistent, bioaccumulative, toxic (PBT) risk assessments. However, an increasing number of studies have illustrated that antibiotics are responsible for the global increase in antimicrobial resistance (AMR), which suggests that the risk of antibiotics has been largely underestimated by using PBT risk assessment. Here, we designed an integrated innovation risk assessment framework of persistent, bioaccumulative, toxic, and resistance (PBTR) that accounts for antibiotic resistance to better represent the antibiotic environmental risk. This novel antibiotic risk assessment framework was further verified via application to 39 target antibiotics in the 23 drinking water sources of the lower Yangtze River (LYR), China, during the normal and flood seasons. In contrast with the PBT assessment, single toxicity assessment and single resistance assessment, in the PBTR assessment, 7 of 39 target antibiotics with bacterial insensitivity were observed to represent a more prominent risk, as were the sites sampled during the flood season with low concentrations but high pollution loads, which confirmed that the sensitivity of PBTR risk assessment was instructive. The PBTR risk assessment for the screened priority antibiotics contributes not only representative data but also an innovative approach for identifying resistance risks. Using the positive matrix factorization (PMF) model, the sources of priority antibiotics can be predicted and thus supported the corresponding policy. Overall, this study first constructed a PBTR risk assessment framework, then applied it to facilitate the accurate management of antibiotic pollution at the basin level.

Assessment of Metallic Contamination in Soils and Sediments in the Bétaré-Oya Gold Artisanal Mine District, East-Cameroon

Mining is an activity that involves the use of chemicals and results in unsustainable and dangerous conditions for the miners, their families, the community and the surrounding ecosystem. This study was done to assess metallic contamination of soils and sediments in the Bétaré-Oya gold artisanal mine district, East-Cameroon. A total of thirty (30) samples of exploited soils, control soils and sediments were taken from the mining sites of Lom, Mbal and Mali. The concentrations of heavy metals and metalloids (Fe, Sr, Cu, As, Pb and Zn) were determined by Inductive Plasma Ionisation Source Atomic Emission Spectrometry. The results show that in the sediments metals such as: As (1.82), Cu (24.22), Pb (18.04) and Zn (65.69) have average concentrations slightly higher than the UCC and Average Shale reference values. In the exploited soil As (1.93), Cu (16.86) and Zn (96.22) have average concentrations slightly higher than the UCC and Average Shale reference values.While in the cotrol soils only As (1.62) and Zn (59.72) shows an average concentration slightly above the UCC reference values. The average concentrations of the different heavy metals and metalloids were then used to calculate the intensity of contamination in soils and sediments. The results of this calculation indicate that the Enrichment Factor (EF) of As, Sr, Zn and Pb indicate an extremely high enrichment in these elements. The geo-accumulation Index (Igeo) (22.85-25), the Contamination (CF) (1.47), the low values of the ecological risk indices suggest a low potential ecological risk and Pollution load index (PLI) (0.67) indicates extreme contamination with these elements in the soils and sediments. However, only As indicates a slight contamination (class 1) in soils and sediments. Gold panning activities and untreated mine tailings discharges would be considered as the main sources of sediment and soil pollution in Bétaré-Oya.

The bryophyte community as bioindicator of heavy metals in a waterfall outflow

The species diversity and heavy metal accumulation in bryophytes were determined in Huay Pah Lahd stream in Doi Suthep-Pui National Park, Thailand. Eight bryophytes from two major taxonomic groupings (epilithic mosses and liverworts) were investigated. Of these, Fissidens crispulus var. crispulus was the most dominant taxon with an importance value (IV) of 28.98%, while Ectropothecium zollingeri, Claopodium prionophyllum, and Hyophila involuta were also dominant taxa with IV ≥ 10%. Scopelophila cataractae, a rare moss species with the lowest IV (0.91%) had the greatest capacity to accumulate metals in tissue, particularly Fe, Zn, Cd and Cu in protonemata (8026.7, 1187.2, 16.9 and 530.1 mg kg−1, respectively). The highest enrichment factors (EFs) of Zn, Cd and Cu (5.3, 2.4 and 0.9, respectively) were also found in S. cataractae, while the highest EFMn (1.1) was found in H. involuta. Enrichment factors of most heavy metals were < 5 from the study bryophytes, which suggests that natural processes were the key source of heavy metals. Dilution effects caused by increased water volume during the rainy season may be responsible for low pollutant loads and the maintenance of good water quality in this waterfall stream, which is favorable for biota and general environmental health.

Optimization of the coagulation-flocculation process for vegetable oil refinery wastewater using a full factorial design

Vegetable oil refineries wastewater poses significant challenges to treatment techniques due to its characteristic fluctuations. In this study, a full factorial design (FFD) was applied to investigate the effect of the experimental variable (pH, coagulant dose, flocculant dose, and pollutant load) for the turbidity (Y1) and COD (Y2) removal by the coagulation-flocculation process. The results showed that the linear regression models were well suited to the experimental data, with correlation coefficients R2adj of 0.96 and 0.9 for Y1 and Y2, respectively. According to the ANOVA analysis, linear effects were detected significantly for the four factors examined on turbidity and COD removal. This study has shown that coagulation-flocculation is effective for turbidity removal, regardless of the pollutant load of wastewater. Under optimal conditions using 1 g L−1 FeCl3 and 1 mL L−1 cationic polymer at a pH = 8, the turbidity removal reaches 82% and 97.5% for a low and high pollution load, respectively. In contrast, the COD removal reaches 79.5% and 58% for low and high pollution loads, respectively. These results prove that the efficiency of physicochemical treatment in organic matter removal is more effective in less polluting industrial wastewater. This strongly suggests that a physical pretreatment is a promising option for the best efficiency of coagulation-flocculation.

Growth Performance of Black poplar (Populus nigra L.) Under Drought Condition and Sewage Water Irrigation

The response of black poplar (Populus nigra L.) seedlings to the combination of both drought and sewage water irrigation have been investigated from 18-5-2019 to 18-8-2019. Two drought stress levels; D0; 90% or full water holding capacity (WHC) and D1; 30% WHC interacted with three sewage irrigation treatments; S0; 100 % of tap water as a control, S1; 50% of tap water and sewage water and S2; 100% of sewage water. The irrigation water quality index (IWQI) of S1 was 59.31 located under moderate restrictions class for irrigation purposes. Despite to its low pollution load index (PLI); 0.47. Fully irrigation to soil holding capacity with S1 (S1D0) led to a significant increase in seedling height, stem base diameter, fresh and dry biomass and moisture content in shoot system. In addition, the highest tolerance index (TI %) about 92.07 % of the seedlings recorded despite to the soil toxicity with Ni and Pb ions. Lowest accumulation and metal toxicity of Cu, Zn, Cd, Pb and Mn in the soil and leaves have been determined. Thus, diluting sewage water; 1:1 can be used to irrigate black poplar trees with high water demand and moderate to high tolerance to salts for reforestation and urban vegetation.

Towards Risk Assessments of Microplastics in Bivalve Mollusks Globally

The ubiquitous presence of microplastics in bivalve mollusks and related risks have raised particular concerns. In this study, the available data on the abundance and polymer type of microplastics in bivalves from twenty-two countries were extracted to comprehensively understand the risks of microplastics in bivalves. Following the data from 52 peer-reviewed papers, the abundance, chemical composition, and human exposure risks of microplastics of bivalves among countries were initially assessed. Abundance risk results indicated that bivalves from 22 countries presented a low pollution load index, showing a lower risk level (level I). The polymer risk index (H) of bivalves from Portugal (Hcountry = 1335, level IV) and India (Hcountry = 1187, level IV) were higher than the other countries due to the occurrence of hazardous microplastics, such as polyvinyl chloride. For the human exposure risks, the global mean value of microplastic exposure to humans via mollusk consumption is estimated to be 751 microplastics/capita/year, with the maximum intake by the Chinese. This study suggests that abundance risk may be a fundamental indicator for assessing the potential hazard to humans until the chemical composition risks are confirmed. This study is the first attempt to assess the potential risks of microplastics in bivalves using three evaluation models based on microplastic abundances and polymer types, which will contribute to establishing future human health risk assessment frameworks. These findings will also assist efforts in policy-making to minimize microplastic risks in seafood.

Macronutrients, trace metals and health risk assessment in agricultural soil and edible plants of Mahshahr City, Iran.

In this study, we evaluate the geochemistry of macro- (Fe, P, Ca, S, K, Na, Mg) and micronutrients (Mo, Cu, Pb, Zn, Co, Mn, Cd, Sr, Cr, Hg, Se), along with possible health risks of heavy metals contamination in agricultural soils and vegetables of the Mahshahr industrial port in Iran. Calculation of geochemical coefficients revealed the low pollution load of Mahshahr agricultural soils. Most of the investigated elements exhibited lower concentrations in soil than international standards. Element concentrations in plant samples were far below the permissible values set by environmental agencies. Based on permissible values, there was deficiency of several soil elements, including Cu, in vegetables because they are mostly present in the soil residual phase. An exception was Mn, which is the most mobile element in soil. The transfer factor (TF) of elements showed the following trend: K > Na > P > S > Mo > Hg > Se > Zn > Cd > Cu > Mg > Mn > Ca > Cr > Co ≈ Fe = Pb. There was high transfer of major elements from soil to plants, and lower values for micronutrients and heavy metals. The calculated daily intake (DIM) and health risk index (HRI) for ten plant species for adults were < 1, while the HRI was larger than 1 for Mn via radish consumption. According to geochemical investigations and statistical tests such as principal component analysis, Kruskal-Wallis, and correlation coefficient calculations, plant species play the most important role in elemental uptake by plants.

Extract of Trema Orientalis (L.) Stem Bark: A Potential Source of Environmentally Friendly Tanning Agent for Leather Industry

Researchers around the world are in continuous endeavor to develop environment friendly tanning agent due to adverse effect of conventionally used chromium during leather tanning. Recent trend of tanning is thus heading to chrome-free and greener chemical processing options. Vegetable tanning is an exoteric leather processing technique because of their lower pollution load on the environment. Considering the inadequacy and high costing for the commercialized tannins, development of alternative tannins from locally available plants and their characterizations are important. In this research, the stem barks of Trema Orientalis (L.) were extracted at different temperatures employing water solvent with or without additives (sodium hydroxide or sodium sulphite) to attain phenolic-rich extractives. To ascertain appropriateness as a vegetable tanning agent, the obtained extracts were thereafter characterized in respect to yield, total phenolic content, tannin content and molecular structure. The extraction yield for all extracts improves and the quality remains nearly unchanged with temperature rising. The elevated concentration of chemical additives enhances the extraction yield but lessens the quality of extracts. In terms of extraction yield and the quality of extracts the best condition for extraction was discerned at 80°C with water solvent. This water extract has a decent extent of phenolic and tannin content of 266.13 mg Gallic acid equivalent/ gm of dry extract and 30.12 % respectively. The final extract exhibits excellent leather retanning tendency comparable to the commercial quebracho tannins.

Efficient and sustainable treatment of industrial wastewater using a tannin-based polymer

ABSTRACT Paint, tannery and textile manufacturing wastewaters contain highly toxic and organic biorefractory compounds and have adverse effects on human health. These effluents require efficient and environment friendly solutions before being discharged. Jar-test experiments are conducted in order to assess the efficiency of a tannin-based polymer (TBP) on the treatment of these industrial wastewaters. The results indicate that TBP is more effective than classical coagulant iron chloride. Coagulation flocculation involving TBP does not require any coagulation pH adjustment, reduces more than 96% of colour and achieves 60, 65 and 87% of COD removal from textile, tannery and paint wastewater respectively. Compared to iron chloride, TBP produces the least amount of sludge for a given amount of COD and colour removed. It produces 28 to 60 % less volume of sludge than FeCl3, and generates a good settling sludge with lower values of SVI (31- 80 ml g−1). Furthermore, TBP allows 4 to 6.5% of water recovery more than FeCl3. Utilisation of such polymer represents an important progress in sustainable environmental technology as it is a renewable resource and allows a lower pollution load, a good settling sludge and an adequate water recovery.

Design of Bio-Absorbent Systems for the Removal of Hydrocarbons from Industrial Wastewater: Pilot-Plant Scale.

The objective of this study was the development and design of a treatment system at a pilot-plant scale for the remediation of hydrocarbons in industrial wastewater. The treatment consists of a combined approach of absorption and biodegradation to obtain treated water with sufficient quality to be reused in fire defense systems (FDSs). The plant consists of four vertical flow columns (bioreactors) made of stainless steel (ATEX Standard) with dimensions of 1.65 × 0.5 m and water volumes of 192.4 L. Each bioreactor includes a holder to contain the absorbent material (Pad Sentec polypropylene). The effectiveness of the treatment system has been studied in wastewater with high and low pollutant loads (concentrations higher than 60,000 mg L−1 of total petroleum hydrocarbons (TPH) and lower than 500 mg L−1 of TPHs, respectively). The pilot-plant design can function at two different flow rates, Q1 (180 L h−1) and Q2 (780 L h−1), with or without additional aeration. The results obtained for strongly polluted wastewaters showed that, at low flow rates, additional aeration enhanced hydrocarbon removal, while aeration was unnecessary at high flow rates. For wastewater with a low pollutant load, we selected a flow rate of 780 L h−1 without aeration. Different recirculation times were also tested along with the application of a post-treatment lasting 7 days inside the bioreactor without recirculation. The microbial diversity studies showed similar populations of bacteria and fungi in the inlet and outlet wastewater. Likewise, high similarity indices were observed between the adhered and suspended biomass within the bioreactors. The results showed that the setup and optimization of the reactor represent a step forward in the application of bioremediation processes at an industrial/large scale.

Technical evaluation and optimization of biological aerated filter (BAF) treating micro-polluted source water at low temperature

In this study, polyethylene and zeolite, as media in two-stage biological aerated filters (BAF), were evaluated for simultaneous removal of ammonia nitrogen and organics in micro-polluted water under low temperature conditions. For specific source water, the contaminants removal characteristics are evaluated by single-factor experiment to determine the suitable pH, air-water ratio (AWR) and hydraulic load ratio (HLR). Ammonia nitrogen and permanganate index in BAFs were promoted effectively with pH = 7~8, AWR = 1.0:1.0~2.0:1.0, HLR = 1~4 m3/(m2·h), low pollution loads and a temperature of 10°C. Based on the response surface analysis, the optimum parameters were as follows: pH of 7.94, AWR of 1.41:1.0 and HLR of 1.39 m3/(m2·h), for simultaneous removal of ammonia nitrogen and permanganate index, their removal rates were respectively 59.76% and 18.16%. BAF has a great advantage in emergency treatment of low temperature micro-polluted water, and response surface analysis can be used to optimize operating parameters.

Application of sludge-derived KOH-activated hydrochar in the adsorptive removal of orthophosphate.

Hydrochar, a hydrothermally carbonized product, has gained attention recently as an adsorbent, among its wide environmental applications. In this study, sludge from the paper recycling industry, having a lower pollution load, was used to produce hydrochar, followed by pre-activation and post-activation using KOH. Characterizations were performed for structural morphology (SEM and TEM), molecular functionalities (FTIR) and textural features (BET surface area). Furthermore, Response Surface Methodology (RSM) was used to optimize the adsorption parameters for the removal of orthophosphate with different hydrochars. This study aimed at a low-cost, waste-to-wealth, and negative emission technology for simultaneous solid waste management and orthophosphate removal in aqueous solution. It was predicted from the adsorption experiment that an orthophosphate dose of 100 mg L−1 at substrate pH 5.11 will result in the adsorption of 9.59 mg orthophosphate per g of post-activated hydrochar after 28.6 h, which was validated using further confirmation study.

Valorization of Opuntia ficus-Indica Pads and Steel Industry FeCl 3 -Rich Rejection for Removing Surfactant and Phenol from Oil Refinery Wastewater Through Coagulation-Flocculation

Background.Refinement of crude vegetable oil generates a large amount of wastewater and is a source of water pollution due to the presence of surfactants and phenols. Phenols are toxic aromatic compounds that can be lethal to fauna and flora, entraining the deceleration or blocking of the self-purification of biological treatments. In addition, surfactants can limit biological processes by inhibiting microorganisms that degrade organic matter.Objectives. The aim of the present study was to evaluate the treatment of refinery rejects loaded with phenols and detergents by coagulation flocculation using cactus pads (genus Opuntia) as a bio-flocculant and 30% iron(III) chloride (FeCl3) for surfactant and phenol removal. In addition, operating costs were evaluated for these pollution mitigation methods.Methods.The effectiveness of cactus pads as a bio-flocculant and 30% FeCl3 for surfactant and phenol removal were studied using a jar test. The study was conducted on vegetable oil refinery wastewater from a refinery company in Casablanca, Morocco.Results.The pollution load in wastewater varied widely from day to day. We evaluated the effect of cactus juice and 30% FeCl3 on high and low pollution loads. Opuntia pads showed a favorable potential for the treatment of low pollution load wastewater, with 78% and 90% of surfactant and phenol removed, respectively. However, the removal of high pollution load was less effective (42% and 41% removal of surfactant and phenol, respectively). The turbidity of low and high pollution load was reduced by 98.85% and 86%, respectively. The results demonstrate that 30% FeCl3 can effectively treat both low and high pollution loads (90% and 89% phenol removal, respectively, and 90% and 70% surfactant removal, respectively (optimal concentration 1.48 g/l). The turbidity was reduced by over 96% for both high and low pollutants.Conclusions.The results of the present study indicate that cactus as a natural flocculant and reject rich in FeCl3 could be effectively used for the low-cost effective treatment of crude vegetable oil refinery rejects.Competing Interests.The authors declare no competing financial interests

Characteristics of rural domestic wastewater with source separation.

Rural domestic wastewater (RDW), one of the non-point pollution sources, has become a significant object related to sanitation improvement and water pollution control in Taihu Lake Basin, China. Current research on RDW characteristics and management with source separation is limited. In this study, a source-separated investigation into the characteristics of RDW was conducted, and the management suggestions were proposed. The results showed that the average RDW production coefficient was 94.1 ± 31.6 (range: 71.8-143.0) liters per capita (person) per day. Household-level wastewater generation peaked two or three times daily, and the synchronous fluctuation could cause hydraulic loading shocks to treatment facilities. The population equivalents of chemical oxygen demand, ammonium nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) in RDW were 78.7, 3.7, 4.12, and 0.8 g/(cap·d), respectively. Blackwater from water closet source accounted for 30.4% of the total wastewater amount, contributing 93.0%, 81.7%, and 67.3% to loads of NH4+-N, TN, and TP, respectively. Graywater from the other sources with low nutrient-related pollutant concentrations and loads, accounting for 69.6% of the total wastewater amount, was a considerable alternative water resource. The quantitative and qualitative characteristics indicated that GW and BW had the potential of being reused in relation to water and nutrients, respectively.