Central Wastewater Treatment Plant Research Articles

Can wastewater feed cities? Determining the feasibility and environmental burdens of struvite recovery and reuse for urban regions

Phosphorus (P) resources are decreasing at an alarming rate due to global fertilizer use and insufficient nutrient recovery strategies. Currently, more circular approaches are promoted, such as recovering P from wastewater in the form of struvite. This is especially attractive for urban areas, where there is a growing trend of local crop production and large volumes of wastewater are treated in centralized wastewater treatment plants (WWTPs). This research aims to assess the technical and environmental feasibility of applying a struvite recovery and reuse strategy to meet the P requirements to fertilize the agricultural fields of an urban region. To do so, we analyze the potential P recovery and the environmental impacts of integrating three recovery technologies (REM-NUT®, Ostara® and AirPrex®) in the two biggest WWTPs of the Àrea Metropolitana de Barcelona. The results show that all technologies are able to recover between 5 and 30 times the amount of P required to fertilize the agricultural area of the region annually (36.5 t). As can be expected, including P recovery technologies result in additional impacts per m3 of wastewater due to increased electricity consumption and chemicals required for the struvite precipitation. However, struvite recovery results in less eutrophication potential, especially in the REM-NUT® case, with an average reduction of 5.4 times. On the other hand, Ostara®, that recovers P from the digestate, had the lowest impacts (9 kgCO2eq/kgP), even compared to the production of mineral fertilizer. When we apply our findings to the whole region, we can see that chemical use for struvite precipitation and energy consumption during the wastewater treatment process are the elements with the greatest impact. Thus, choosing the most appropriate technology in the most suitable WWTP is the most efficient strategy to diminish the environmental impacts of the system.

Eco‐efficiency of water and wastewater management in food production: A case study from a large dairy in Denmark

AbstractRising water demands and pressures on water resources call for water management in industrial production. An eco‐efficiency framework may provide justification for water consumption and treatment by combining environmental and economic dimensions in a life cycle perspective. We used principles of value added and value chain assessment (VCA) in the life‐cycle system boundaries for a consistent assessment of eco‐efficiency. The method was demonstrated for a membrane bioreactor‐based, decentralized wastewater treatment and reuse in a dairy. The LCA results showed that decentralized wastewater treatment and reuse in the dairy will improve the aquatic environment by 80% (freshwater) and 51% (marine water), but increase the negative impact on climate change by 27% compared to conventional wastewater treatment. The VCA revealed that the decentralized alternatives would increase the value added by 1.3–1.4 €/m3 wastewater in the dairy, but also incur a value loss of 1.4–1.9 €/m3 for associated stakeholders such as the centralized wastewater treatment plant. The case study revealed the critical nature of a well‐defined system boundary that includes impacts along the entire value chain and exposed pros and cons for decision‐makers at both the system level and individual stakeholder level.

Utilization of Wastewater Management for Sustainable City Environment in Abuja, Nigeria

Wastewater contribute to many damages to the ecosystem and biodiversity, it encompasses domestic, commercial, industrial and agricultural components and also faecal sludge, to prevent this sensitive damage, wastewater need to be well treated before being discharged to the environment or water bodies, otherwise it contributes to some disease outbreak like malaria and typhoid. Extreme poverty with inequality of income, housing system and poor urban planning combined with rapid increase in population mostly found in low/lower class settlement are among those factors contributing to these challenges and this study determines the health and environment impact of untreated wastewater. The comparative study was carried out in two study areas; highbrow areas that makes use of central wastewater treatment plant known as “WUPA” and low/lower income areas that practice open surface wastewater discharge, to determine how frequent both residents treats malaria/typhoid and soil pH value of the study areas also analyzed.
 In-house survey questionnaire for 300 respondents of children below 12 years was employed which show that average 65% of residents in highbrow areas treated both malaria/typhoid once in 6 months, while 64% in the low/lower class areas treated 4 times in 6 months and with an average pH value of 8.18 for highbrow areas and 7.51 for low/lower class areas. This study recommends that government should connect all areas to the treatment plant, implement proper urban planning, awareness and with enforcement.

Model of Carbon Footprint Assessment for the Life Cycle of the System of Wastewater Collection, Transport and Treatment

This article presents a model of the environmental assessment of the system of wastewater collection, transport and treatment. The model was developed based on an original environmental assessment method of a system consisting of four elements: septic tanks, household wastewater treatment plants, a sewerage system and a central wastewater treatment plant. To conduct the environmental assessment, the Life Cycle Assessment technique was applied. The Intergovernmental Panel on Climate Change (IPCC) method was also applied, which enabled the determination of the carbon footprint of the analysed wastewater management system. This article presents the outline of an original method applied to create a model and an inventory of the data necessary for environmental assessment and the application of the model for the environmental assessment of a system of wastewater collection, transport and treatment in a city with over 50.000 inhabitants. Three feasible variants (from a functional, technical, organizational and financial point of view) of the system’s development were analysed. The variants were subjected to comparative analysis using the solution. The obtained results, together with the assessment method can be used as a practical tool to assess whether the European Commission’s guidelines are met, as well as the challenges facing wastewater management in the circular economy are overcome.

Assessing environmental impacts of large centralized wastewater treatment plants with combined or separate sewer systems in dry/wet seasons by using LCA

Rainfall can affect influent flow rate and compositions of wastewater, and thus further affect wastewater treatment performance and the effluent quality. This study aims to study the influence of rainfall on the environmental impacts of centralized wastewater treatment plants. The correlations between rainfall, and influent flow rate and compositions of wastewater in wet and dry seasons with two sewer systems, i.e. combined and separate sewer systems, were primarily established. Environmental impacts were assessed with life cycle assessment (LCA) to understand the temporal environmental burdens in wet and dry seasons. Functional units as per m3 treated wastewater (FU1) and as per kg PO43-eq. removed (FU2), respectively, were used to evaluate impacts of wastewater treatment to the environment. Strong correlation between rainfall and the influent flow rate was found in the wastewater treatment plants with either a combined sewer system (with Pearson correlation coefficient r at 0.66) or a separate sewer system (with r at 0.84), where r represents the strength of the association between two variables. The rainfall effect is more obvious on the eutrophication potential and global warming potential than on other environmental indicators while sewer system, i.e. combined or separate, seems not important in the two cases studied. Both wastewater treatment plants (WWTPs) show a lower environmental burden in the wet season than in the dry season partially due to the dilution of wastewater by using FU1. The WWTP receiving high strength wastewater, however, demonstrates higher environmental impacts in the wet season by using FU2 than FU1, due to the less efficient treatment caused by heavy rainfall. Meanwhile, it is found that environmental impacts from the WWTP receiving low strength wastewater have no difference when using either FU1 or FU2. The results indicate that the environmental burdens particularly eutrophication and global warming caused by WWTPs are dependent on the correlations of rainfall intensity with wastewater quantity and quality instead of combined or separate sewer system. This could be used to guide a stricter control of eutrophication in a more sensitive season in more vulnerable receiving waters.

Sustainable solutions for urban wastewater management and remediation

Sustainable development with environmental protection is one of the greatest challenges of the 21st century. There is a growing consideration of the sustainable development and environmental management in new industrial cities. Investigational aspects were carried out in El Obour city as Egyptian new industrial city for estimating the current wastewater problems as well as applying mitigation actions. Industrial inventory was constructed for selected industrial sectors as food, chemical and textile sectors including water consumption, materials and energy resources. Wastewater samples from different factories and lifting stations were analyzed for estimating the industrial effluent loads. The obtained data revealed that food sector represents the highest load for BOD and TSS with values of 80 ton BOD/day and 2.33 ton SS/day. For selected industrial sectors, cost-effective technology is applied to reduce the loads on the centralized wastewater treatment plant (WWTP) as well as on the lifting stations. Inorganic polymeric ferric chloride (POFC) coagulant gives higher removal efficiency for TSS and COD without pH control. Moreover, the chemicals cost for treating wastewater is reduced by 40 % with using POFC instead of conventional coagulants.

Exploring the cost of wastewater treatment in a chemical industrial Park: Model development and application

In light of the environmental policy orientation of continuous upgrading emission limits, quantitatively understanding the comprehensive cost of wastewater treatment of chemical industrial parks, a common landscape globally, will be vital for facilitating sustainable water management of the parks. This study modeled the economic cost of wastewater treatment in chemical industrial parks from the perspective of life cycle thinking. The full-process cost of wastewater treatment is accounted, including freshwater withdrawal, construction and capital costs of wastewater treatment facilities, operation costs, sludge treatment costs, and ‘feed-in tariffs’ of wastewater to centralized wastewater treatment plants (CWWTPs) of the park. After applying the model to HSEDA, a typical chemical industrial park, we found the total wastewater treatment cost of the chemical industrial park in 2016 was 654 million Chinese Yuan (about 97 million USD), accounting for 29 % of the tax revenue of the park. Energy, chemicals, and labor costs in the sum accounted for more than 60 % of the full-process cost. The cost of freshwater withdrawal, in-plant treatment cost, and CWWTP cost accounted for 54 %, 33 %, and 13 % of the total cost, respectively. The top two pillar industries—the dyestuff manufacturing industry and the pharmaceutical industry—, have a cost of 29 CNY and 21 CNY per ton of wastewater, respectively. Moreover, the marginal cost increment associated with a much stricter emission standard by targeting TN control is discussed by employing different technologies. Finally, key measures for improving wastewater treatment in the chemical industrial park are proposed.

Impact of Climate Change on the Performance of Wastewater Treatment Plant: Case study Central Irbid WWTP (Jordan)

Limited studies were carried out to assess the impact of climate change on the performance of wastewater treatment plants (WWTPs). Therefore this study aims to assess the consequences of climate change on the central Irbid WWTP which is located in northern Jordan. For this purpose the statistical downscaling Model (SDSM) and the outputs of the HadCM3 global climate model were used to produce two climate change scenarios A2 and B2. The two scenarios cover the periods 2050-2065 and 2080-2099. These scenarios were used conjunction with a wastewater simulation model (STOAT) to assess the impact of climate change on the performance of the Central Irbid WWTP. The results revealed that the BOD removal will increase in summer season by about 6 mg/l for periods 2050-2065 and 2080-2099 under both Scenarios A2 and B2. For winter season it is expected that the BOD removal will be reduced up to 8 mg/l. On the other hand, the results indicated an improvement in COD removal up 6 mg/l in the summer season while in the winter it is expected to decree mg/l. The removal of TSS was slightly affected by the climate change

Identifying Amsterdam's nutrient hotspots: A new method to map human excreta at building and neighborhood scale

AbstractRecovering nutrients from human excreta and wastewater has been receiving increasing attention as a means to supplement or replace synthetic fertilizer production. Apart from technologies for nutrient recovery at centralized wastewater treatment plants, numerous decentralized, source‐separated sanitation systems, also known as new sanitation systems, have been developed to facilitate recovery. Decision‐making for the planning and implementation of new sanitation systems would benefit from a spatially explicit inventory of nutrient hotspots in urban areas. To provide visual representations of nutrient loads, we developed a methodology that combines spatial‐temporal modeling with geographic information system analysis, and used it for the city of Amsterdam. The methodology is new in the field of nutrient mapping, especially at the smallest geographical scale: building. Nitrogen, phosphorus, and potassium loads and hotspots are mapped at both building and neighborhood scale, drawing attention to the need for multiple scale analyses in decision‐making. This study concludes with a discussion on the potential to further develop the method proposed to include more detailed and verified data and to identify nutrient hotspots that are promising as nutrient recovery sites with new sanitation systems.

Nitrous oxide (N2O) emissions during real domestic wastewater treatment in an outdoor pilot-scale high rate algae pond

In order to determine if nitrous oxide (N2O) emissions could affect the sustainability of microalgae-based pond systems, N2O emissions were recorded from an outdoor 900 L pilot high rate algal pond (HRAP) fed primary wastewater over 1 year. The HRAP was mixed using a paddle wheel and operated at a hydraulic retention time (HRT) of 7.5–10 days. Direct N2O emissions ranged from 4.1 to 6400 μg N-N2O·m−2·d−1 (median of 560 μg N-N2O·m−2·d−1, n = 28) at 10 days HRT, and 70–18300 μg N-N2O·m−2·d−1 (median of 4200 μg N-N2O·m−2·d−1, n = 22) at 7.5 days HRT. Using 25–75% of the data, we estimated that HRAPs designed for nitrogen removal operated at 7.5 days HRT (i.e. 9.5 m2·capita-1 required) would generate 12–53 g N2O·capita·yr-1 which is 4–17 fold higher than the default value of 3.2 g N2O·capita·yr-1 given by the Intergovernmental Panel on Climate Change for centralized wastewater treatment plants with controlled nitrification and denitrification steps. When indirect N2O emissions (via nitrogen discharge and ammonia volatilization) are included, a HRAP operated at 7.5 days HRT could generate total emissions equivalent to 21–138 g N2O·capita−1·yr−1. When expressed as a % of the nitrogen input load into the system, the HRAP direct emissions (i.e. 0.13–0.57%) and total (i.e. 0.23–1.5%) where within the range of 0–14.6% reported in the literature for centralized wastewater treatment.

Metagenomic analysis of β-lactamase and carbapenemase genes in the wastewater resistome

The emergence and spread of resistance to antibiotics among bacteria is the most serious global threat to public health in recent and coming decades. In this study, we characterized qualitatively and quantitatively β-lactamase and carbapenemase genes in the wastewater resistome of Central Wastewater Treatment Plant in Koziegłowy, Poland. The research concerns determination of the frequency of genes conferring resistance to β-lactam and carbapenem antibiotics in the genomes of culturable bacteria, as well as in the wastewater metagenome at three stages of treatment: raw sewage, aeration tank, and final effluent. In the final effluent we found bacteria with genes that pose the greatest threat to public health, including genes of extended spectrum β-lactamases – blaCTX-M, carbapenemases – blaNDM, blaVIM, blaGES, blaOXA-48, and showed that during the wastewater treatment their frequency increased. Moreover, the wastewater treatment process leads to significant increase in the relative abundance of blaTEM and blaGES genes and tend to increase the relative abundance of blaCTX-M, blaSHV and blaOXA-48 genes in the effluent metagenome. The biodiversity of bacterial populations increased during the wastewater treatment and there was a correlation between the change in the composition of bacterial populations and the variation of relative abundance of β-lactamase and carbapenemase genes. PCR-based quantitative metagenomic analysis combined with analyses based on culture methods provided significant information on the routes of ARBs and ARGs spread through WWTP. The limited effectiveness of wastewater treatment processes in the elimination of antibiotic-resistant bacteria and resistance genes impose the need to develop an effective strategy and implement additional methods of wastewater disinfection, in order to limit the increase and the spread of antibiotic resistance in the environment.

Water-reuse concepts for industrial parks in water-stressed regions in South East Asia

Abstract With regard to the water shortage in several regions of South East Asia, the paper focuses on the development of a sustainable Industrial WasteWater Management Concept with the focus on Reuse (brand name: IW2MC → R) to reduce water consumption from natural resources. The IW2MC → R includes the sustainable treatment of wastewater in industrial parks (IP) to provide reuse water for different purposes. The main objective is to reach the highest possible Industrial Park Reuse Factor (IPRF). The IPRF describes the relation between wastewater inflow to the central wastewater treatment plant and the outflow of reuse water for different applications. The Infrastructure Reuse Factor (IRF), one component of the IPRF, relates to infrastructural reuse applications (e.g. irrigation, street cleaning, toilet flushing). To determine the IRF, a model industrial park is applied. A first calculation resulting in an IRF of ∼25% includes reuse applications for irrigating green spaces, street cleaning, and toilet flushing. In cases when other applications for reuse water are considered (e.g. cooling or firefighting water), the IRF can be higher than 25%. Thus, the IW2MC → R provides a sustainable solution strategy, especially for water-stressed regions, to drive new IP developments by reducing water extraction from natural resources.

Field-Scale Co-fermentation of Solid Waste From Urine-Diverting Dry Toilets (UDDT-SW) and Banana Waste to Produce Undissociated Carboxylic Acids to Inactivate Ascaris Eggs

Innovative, low-cost methods for inactivating pathogens in human fecal material (HFM) are needed, particularly in expanding urban areas where conventional sewer systems and centralized wastewater treatment plants are not feasible. To address this challenge, we have developed a bioprocess that utilizes open cultures of anaerobic bacteria (i.e., microbiomes) to produce carboxylic acids using HFM as substrate. When the pH is sufficiently low, the carboxylic acids exist in the undissociated form and inactivate pathogens. Here, we used real sanitation waste collected from container-based, urine-diverting dry toilets (UDDT-SW) in Nairobi, Kenya to conduct lab-scale and field-scale trials. Through these trials, we investigated operating conditions required to use carboxylic acid fermentation in sanitation waste treatment processes. We tested three different inoculum treatments and determined that the microbiome in UDDT-SW is well suited to produce carboxylic acids without the need for an external inoculum. We also tested co-fermentation of UDDT-SW with carbohydrate-rich food waste as a means of reducing the pH. We found that when food waste was incorporated in a way that maintained the pH between 4.8 and 5.2, then the food waste was quickly converted to carboxylic acids, and the low pH created high concentrations of undissociated carboxylic acids. The resulting concentrations of undissociated carboxylic acids resulted in Ascaris inactivation within 15 days. However, we found that a temperature ≥30°C is required for carboxylic acid production to occur.

Performance analysis and life cycle greenhouse gas emission assessment of an integrated gravitational-flow wastewater treatment system for rural areas

Due to the lack of appropriate wastewater treatment facility in rural areas, the discharging of wastewater without sufficient treatment results in many environmental issues and negative impact on the local economy. In this study, a novel integrated gravitational-flow wastewater treatment system (IGWTS) for treating domestic wastewater in rural areas was developed and evaluated. As the core module of IGWTS, the multi-soil-layering (MSL) system showed good performances for removing organic matters and nutrients in lab-scale experiments. Aeration was found to be the dominant positive factor for contaminant removal in factorial analysis, while bottom submersion had the most negative effect. Based on the critical operational factors obtained from lab-scale tests, the full-scale IGWTS consisting of multifunctional anaerobic tank (MFAT), MSL, and subsurface flow constructed wetland (SFCW) was designed, constructed, and operated successfully in the field application. The final effluent concentrations of COD, BOD5, TP, NH3-N, and TN reached 22.0, 8.0, 0.3, 4.0, and 11.0mg/L, with removal rates of 92, 93, 92, 86, and 76%, respectively. The feasibility of IGWTS was also quantitatively evaluated from the perspectives of resource consumption, economic costs, water environment impact, and life cycle greenhouse gas (GHG) emissions. IGWTS has been proved to be a sound approach to mitigate GHG emissions compared with centralized wastewater treatment plant. It can also be featured as an eco-friendly technology to improve rural water environment, and an economic scenario with low construction and operation costs. Graphical abstract.

The Influence of Temperature Changes in Activated Sludge Processes on Ibuprofen Removal Efficiency

Abstract The article presents results regarding the ibuprofen reduction rate at three various temperature values (8, 18 and 28 °C) which were conducted using a static test in accordance with the PN-C-04645 ‘Water and wastewater. Evaluation of partial biodegradation of anionic and non-ionic surface active substances. Initial test’ standard. A single study cycle including the analysis of ibuprofen degradation rate in specific temperature variants lasted 24 h. The activated sludge for tests was obtained from the aeration zone of a bioreactor localized in the Central Wastewater Treatment Plant in Poznan City (Poland), which was used for inoculation (1 g/dm3) of sterile samples with the medium and ibuprofen (10 mg/dm3) after appropriate pre-treatment (intense aeration for 5 h). The analysis procedure included the separation and concentration of analytes from biodegradation samples by means of solid phase extraction (SPE) and subsequent determination with high performance liquid chromatography coupled with mass spectrometry (LC-MS/MS) using an UltiMate 3000 RSLC liquid chromatogram (Dionex, USA) with a tandem API 4000 QTRAP mass spectrometer (Biosystem, MDS Sciex, USA). Both literature review as well as the conducted initial studies confirmed that the removal of ibuprofen proceeds more rapidly at higher temperature values. A higher retention rate also enhanced the reduction of ibuprofen concentration. A decrease of its concentration was observed after 24 h, which reached 40 and 50 % for temperature values of 8 and 18 °C, accordingly, whereas the highest reduction by approx. 65 % was noted at 28 °C.

A comprehensive index for evaluating and enhancing effective wastewater treatment in two industrial parks in China

Industrial parks have been important to China's rapid economic development. The wastewater generated by these industrial parks tends toward large volumes, varied compositions, high pollutant concentrations, and it generally is toxic and difficult to biodegrade. The abilities of treatment plants to effectively treat industrial wastewater are greatly influenced by the upstream treatment step that occurs at the source in the industrial park. Based on the notion of the water footprint, a wastewater treatment assessment index was developed and tested to evaluate and enhance the centralized wastewater treatment plants of two industrial parks. The treatment performance of a plant in a comprehensive industrial park was compared to that of a chemical industrial park. The former scored significantly higher than the latter. Because of its low scores in the evaluation, the treatment problems of the chemical industrial park were diagnosed and enhancement measures were implemented. After the enhancements were in place, the plant was re-evaluated. Its post-enhancement scores on the index's primary indicator for process advancement and its dependent performance regarding the downstream environment greatly increased, indicating that the wastewater treatment performance had significantly improved. Therefore, the index developed by this study successfully evaluated and determined effective enhancements for wastewater treatment in China's industrial parks, which contributes to industrial wastewater pollution control.

Transformation of dissolved organic matter during full-scale treatment of integrated chemical wastewater: Molecular composition correlated with spectral indexes and acute toxicity

As one of the key economic modes in China, chemical industry park (CIP) has made great contribution to the Chinese rapid economic growth. Concomitantly, how to effectively and safely dispose of the CIP wastewater (CIPWW) has been an unavoidable issue. Molecular transformation of dissolved organic matter (DOM) in CIPWW treatment is essential to optimize the employed process and to provide solid basis for risk evaluation of the discharged effluent as well. In this study, electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to characterize the molecular transformation of DOM during full-scale treatment of integrated chemical wastewater in a centralized wastewater treatment plant (CWWTP), where the combined process follows hydrolysis/acidification (HA)-flocculation/precipitation (FP)-A2/O-membrane bioreactor (MBR)-ultrafiltration (UF)-reverse osmosis (RO). Compared to municipal wastewater, DOM in CIPWW exhibited higher unsaturation degree, lower molecular weight, and higher toxicity. In FP unit, DOM of C<24 and higher nominal oxidation state of carbon (NOSC) values was preferentially removed. The HA and anaerobic units are capable of significantly degrading DOM, resulting in great changes in molecular composition of DOM. However, the anoxic, oxic, and MBR units only lead to a slight change of the molecular formulae. The terminal units of UF and RO can remove most DOM, with the concentration of dissolved organic carbon (DOC) declining by 19.2% and 94.6% respectively. The correlation between spectral indexes and acute toxicity with the molecular formulae of DOM suggested that polyphenols and highly unsaturated phenols were positively correlated with the specific UV absorbance at 254 nm (SUVA254). In addition, both compounds (0.32 < O/C < 0.63) as well as the aliphatic ones (0.22 < O/C < 0.56) presented positive correlation with acute toxicity. Further, the pairwise correlation analysis illustrated that SUVA254, O/Cwa, double bond equivalence (DBEwa), and NOSCwa were positively correlated with each other, whereas the acute toxicity was positively correlated with humification index (HIX), O/Cwa, and DBEwa.

Greenhouse gas emission by centralized wastewater treatment plants in Chinese industrial parks: Inventory and mitigation measures

Wastewater treatment plants (WWTPs) are an important end-of-pipe measure for pollution control and a main energy consumer in industrial parks. WWTPs remove pollutants from wastewater to protect water environments, but produce greenhouse gas (GHG) emissions at the same time. Currently, China has more than 500 national industrial parks (NIPs), and centralized WWTPs are requisite components of environmental infrastructure in these parks. A set of computational methods are established to measure the three main GHGs emitted by the WWTPs in the NIPs, and these GHGs are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). A total of 344 centralized WWTPs in 152 typical NIPs were considered, and their emissions were carefully evaluated. The key findings are as follows, 5.64 million tons (Mt) of CO2-equivalent (CO2-eq) was emitted, and the emissions include 1.63 Mt CO2-eq from on-site emissions, 1.45 Mt CO2-eq from off-site emissions due to energy consumption, and 2.56 Mt CO2-eq from off-site emissions associated with sludge disposal. Aerobic biological treatment is the most frequently used process, and the GHGs emissions associated are 940.6–1,006.9 t CO2-eq/Mt wastewater, which is much lower than the average value (1,441.8) for other kinds of treatment processes. For sludge disposal, incineration is widely applied (131 WWTPs, 86%) to dispose of more than half of residual sludge (1.1 Mt dry sludge per year, 55.7%). However, the 131 WWTPs that used incineration only produced 43% of the total GHG emissions. Scenario analysis showed that building materials applications are the best method of sludge disposal due to low off-site (sludge-related) GHG emissions (0.39 Mt CO2-eq/a), while landfilling (4.23 Mt CO2-eq/a) has the highest emission. Finally, five key measures are proposed to mitigate GHG emissions while considering multiple stakeholders.

Chemical pollutants from an industrial estate in Pakistan: a threat to environmental sustainability

Industrial sector is the backbone of the development of a country; however, its untreated effluents are damaging various ecological phenomena. Every day huge amounts of municipal, industrial and agricultural wastes are being released into the environment, causing serious ecological problems. Pakistan is currently experiencing profound demographic, economic changes and energy crisis that pose serious limitations on spending capital on water treatment. However, no serious effort has been put forth by any agency in Pakistan to characterize the exact nature and concentrations of contaminants found in wastewaters originating from various industrial zones. The current study aimed to characterize the industrial effluent quality of Hattar Industrial Estate, Hattar, Pakistan. The effluent samples were collected from five different drains, each having the combined effluent of many industries. All the samples were characterized for pH, temperature, TS, TDS, TSS, EC, DO, BOD, COD, turbidity, nitrates (NO3–N), phosphates (PO4), ammonia (NH4–N) and different heavy metals according to the standard methods. Majority of the water quality parameters exceeded the National Environmental Quality Standards in the country. These pollutants may have serious impacts on the soil profile, groundwater quality and freshwater ecosystems and thus need attention of policy makers to install a centralized wastewater treatment plant.

Slaughterhouses Wastewater Characteristics in the Gaza Strip

Slaughterhouses generate considerable quantities of wastewater due to the huge amount of blood produced from slaughtering process and the need for cleaning and hygiene of meat. Due to the extraordinary content of organics and minerals, wastewater from slaughterhouses needs special care and treatment for safe disposal to the environment. Currently, wastewater from slaughterhouses in the Gaza Strip is discharged to the public networks without any treatment burdened central wastewater treatment plant, where partially treated effluent discharged to the sea. The aim of this research is to characterize the wastewater from Gaza slaughterhouse to identify the best approach for treatment. Samples from the slaughterhouse were collected during working hours and analysed for physical and chemical parameters. The pH, EC, DO, BOD, TSS, COD, Ammonia Nitrogen and TKN account for 7.1, 3300 μsm, 1.95, 2350, 3500, 4502, 30 and 154 mg/l, respectively. Wastewater from Gaza city slaughterhouse is within the range in comparison to other wastewater from slaughterhouses all over the world.