Wastewater
Wastewater
Wastewater, also written as waste water, is any water that has been adversely affected in quality by anthropogenic influence. Wastewater can originate from a combination of domestic, industrial, commercial or agricultural activities, surface runoff or stormwater, and from sewer inf…
Full Answer
What are the challenges of wastewater treatment in Zambia?
Wastewater treatment. Wastewater treatment plants regularly do not achieve effluent standards. Capacities of plants like the Manchinchi in Lusaka and the Kanini in Ndola have been out-grown by the population.
Does DANIDA support water supply and sanitation in Zambia?
In Nkana it supports water supply and sanitation under a project approved in 2008. Furthermore, a national rural water supply and sanitation program has been approved in 2006. Since 2004 DANIDA supports the Mulonga, Kafubu and Western Water and Sewerage companies.
How can we improve water and wastewater treatment in Africa?
Current practices for water and wastewater treatment in Africa are insuf ficient to ensure safe water and basic sanitation. To address this challenge, joint management, promoting public participation, and establishing water quality standards. biodiversity [1].
Is Zambia on track to achieve Millennium Development Goal for sanitation?
According to National Water and Sanitation Council director Kelvin Chitumbo, Zambia has achieved the Millennium Development Goal for drinking water, but is off track to reach the goal for sanitation.
How is water treated at wastewater treatment plant?
Disinfection by chemical oxidation kills bacteria and microbial pathogens by adding hydroxyl radicals such as ozone, chlorine or hypochlorite to wastewater. These hydroxyl radical then break down complex compounds in the organic pollutants into simple compounds such as water, carbon dioxide, and salts.
How does waste water treatment works?
There are two basic stages in the treat- ment of wastes, primary and secondary, which are outlined here. In the primary stage, solids are allowed to settle and removed from wastewater. The secondary stage uses biological processes to further purify wastewater. Sometimes, these stages are combined into one operation.
How wastewater is treated to make it drinkable?
First of all, wastewater undergoes the standard treatment process. In this procedure, solids and large particles are filtered out through sedimentation tanks. Helpful bacteria are then added to the water to consume the remaining small organic solids. The water is then finely filtered, disinfected and desalinated.
How are sewage treatment plants treated?
Four common ways to treat wastewater include physical water treatment, biological water treatment, chemical treatment, and sludge treatment. Let us learn about these processes in detail. In this stage, physical methods are used for cleaning the wastewater.
How does a water treatment plant clean water?
Disinfection. After the water has been filtered, water treatment plants may add one or more chemical disinfectants (such as chlorine, chloramine, or chlorine dioxide) to kill any remaining parasites, bacteria, or viruses.
What are the 3 stages of wastewater treatment?
There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment.
How is wastewater turned into drinking water?
There are three kinds of water recycling: Non-potable reuse of wastewater for grass irrigation and industrial uses. Indirect potable reuse of treated wastewater that's sent into rivers or underground to mingle with surface or groundwater, and later purified and used for drinking.
Can wastewater be converted to drinking water?
The process of using treated wastewater for drinking water is called potable water reuse. Potable water reuse provides another option for expanding a region's water resource portfolio.
What are the 4 steps of water treatment?
4 Steps of Community Water TreatmentCoagulation and Flocculation. ... Sedimentation. ... Filtration. ... Disinfection.
What are the 7 steps in wastewater treatment?
The Wastewater Treatment ProcessStage One — Bar Screening. ... Stage Two — Screening. ... Stage Three — Primary Clarifier. ... Stage Four — Aeration. ... Stage Five — Secondary Clarifier. ... Stage Six — Chlorination (Disinfection) ... Stage Seven — Water Analysis & Testing. ... Stage Eight — Effluent Disposal.
How does a treatment plant work?
Using internal mechanisms, a sewage treatment plant works by breaking down solid waste to produce a cleaner, more environmentally friendly effluent. Wastewater and sewage are supplied to the primary tank, where the solids and liquids disperse. The resulting liquor flows into the biozone chamber.
How much energy is used in wastewater treatment?
Up to 70% of the energy consumption in a wastewater treatment plant is used for aeration. Additionally, five to ten times the purchase price of a blower will be spent on the energy consumption of the units. Keeping energy costs down is key to keep total operational costs low.
Why is water management important?
Efficient water management becomes increasingly important due to scarce availability of resources and the rising financial pressure. When counting on an air supply to keep the bacteria alive during the treatment process oil contamination is not desirable. That is why our products are oil-free, helping you, in addition to reducing your energy consumption, to further reduce your impact on the environment.
What is backwashing water?
Backwashing refers to pumping water backwards through the filter. Oil-free air prevents filter media from becoming dirty and unusable. It is a form of preventive maintenance so that the filter media can be reused.
Why is air used in activated sludge?
The air in conventional activated sludge systems must be oil free to avoid contamination of the water.
How Does a Waste Water Treatment Plant Work?
A waste water treatment plant cleans sewage and water so that they can be returned to the environment. These plants remove solids and pollutants, break down organic matter and restore the oxygen content of treated water. They achieve these results through four sets of operations: preliminary, primary, secondary and sludge treatments.
Pretreatment Phase
Waste water plants remove the ‘easy pickings’ during the pretreatment phase. A set of bar screens rakes away large items such as tree limbs, garbage, leaves, cans, rags, plastic bottles, diapers and other waste materials.
Primary Treatment
After pretreatment, the waste water collects in primary clarifiers, which are large basins and sedimentation tanks. Gravity allows smaller particles to settle out. Mechanically driven scrapers collect solid matter and direct it to hoppers connected to the sludge treatment equipment.
Secondary Treatment
In the next phase, plants aerate and agitate the waste water in secondary basins, adding beneficial microorganisms to break down organic matter into sludge. Plants employ a number of alternative strategies to break down sludge. For example, plants can culture a mass of microbes and pass the waste material over the biofilm.
Sludge Treatment
The final phase is to treat the remaining water and biosolids, or sludge. Gravity separates organic waste from heavier grit, which can be deposited in a landfill. The remaining primary sludge passes to a thickener, where it is centrifuged and fed to digesting tanks containing anaerobic bacteria.
What is wastewater treatment plant?
A wastewater treatment plant is a facility in which a combination of various processes ( e.g., physical, chemical and biological) are used to treat industrial wastewater and remove pollutants (Hreiz et al., 2015).
How is wastewater treatment plant design based?
Wastewater treatment plant design is based on the selection and sequencing of various unit operations. A schematic illustrating integration of processes capable of treating a variety of wastewaters is shown in Figure 1. Selection of a combination of processes depends on the characteristics of the wastewaters; the required effluent quality (including potential future restrictions); costs; and, availability of land. As previously indicated, treatment methods can be classified as pretreatment/primary treatment; secondary treatment; tertiary treatment; sludge treatment/stabilization; and, ultimate disposition or reuse treatment technologies for residuals.
What is WWTP in wastewater treatment?
WWTPs are a significant point source for AMRDs and antimicrobials. WWTPs are relatively nutrient-rich, heavily contaminated environments that receive waste from a variety of AMRD-loaded environments, including hospitals, industrial and agricultural sites and release both solid and liquid by-products that can disseminate AMRDs. Influent can be contaminated with a variety of pollutants, including antimicrobial agents, pharmaceuticals, personal care products, and heavy metals, which can accumulate within WWTPs. Many microbial and chemical contaminants in wastewater cannot be degraded by the treatment process or inactivated through disinfection of the effluent. For those contaminants that can be degraded, the resulting metabolites may still have antimicrobial or selective activity. WWTP effluent and solid waste products not only have a high prevalence of AMRDs but also release selective agents into the receiving environments ( Jury et al., 2011 ).
How does WWTP affect AMRO?
Andersen (1993) found that microbial community composition in a WWTP affected AMR coliforms. Additionally, different WWTPs have different efficiencies for the removal of AMRO. Both operational conditions and design can influence the fate of AMRDs in WWTPs ( McKinney et al., 2010; Novo and Manaia, 2010; Chen and Zhang, 2013 ). There have been numerous studies to determine which treatment systems and operational conditions impact AMRDs. For instance, Kim et al. (2007) found that both organic loading and growth rate resulted in the amplification of tetracycline resistance in WWTPs using biological treatment processes. Christgen et al. (2015) used metagenomic approaches to compare the fate of AMRDs in anaerobic, aerobic, and anaerobic-aerobic sequence bioreactors (AASs). AASs and aerobic reactors were superior to anaerobic reactors in reducing AMRD abundance, particularly aminoglycoside, tetracycline, and beta-lactam determinants. Sulfonamide and chloramphenicol AMRD levels were unaffected by treatment, and a shift from target-specific AMRDs to AMRDs associated with multidrug resistance was seen in influents and effluents from all WWTP. The AASs used 32% less energy than aerobic reactors and favorably reduced AMRD abundance. The chemical properties of the wastewater, including chemical oxygen demand (COD), ammonia (NH 3 –N), suspended solids (SS), dissolved oxygen, and temperature, can impact the fate of different AMRDs. For instance, Du et al. (2014) found that the COD was highly correlated with the fate of tet W, intI 1, and sul 1. Yuan et al. (2014) indicated that most AMROs and AMRDs were positively related to COD and SS of raw sewage and negatively correlated to the corresponding variables in the effluent.
What is the function of bioreactors in WWTP?
The bioreactors in WWTP function on the principles of biology and so the amount of pressurized air needs to meet the high oxygen demand for aerobic treatment which is energy-intensive and highly-priced. Another irrefutable point about water treatment in WWTP is that the sewage often begins to ferment even before the treatment proceeds. This is where synthetic biology may come into the picture and drive the organic detritus into a renewable energy source in the form of hydrogen or methane. This may readily bring down the BOD and COD of the wastewater.
How is recycled water used?
Recycled water is produced by employing additional treatment steps following conventional sewage treatment to further purify it to a level appropriate for the intended reuse. For example, additional filtration and disinfection steps may be added prior to piping the water for nonpotable applications such as irrigation of crops and recreational fields. If the water is intended for potable application, then more aggressive treatments may be employed. For example, in southern California, the treated wastewater effluent is subject to reverse osmosis, the most selective membrane available in that it is designed essentially to only allow water molecules to pass, prior to injecting the water into an underground aquifer where the drinking water supply is stored. Another promising water treatment technology is the use of advanced oxidation processes (AOPs), which are more aggressive than traditional UV and chlorination disinfection and have the potential to break apart ARGs and gene transfer elements and thus limit the possibility that they will remain functional and spread downstream. Treatments such as reverse osmosis and AOPs are expensive, however, thus calling for research to help guide selection of the right process that balances cost and risk mitigation.
How efficient is WWTP?
Removal efficiency of MPs in a novel pilot-scale WWTP with a microfiltration membrane bioreactor system was also evaluated. A mesh sieve stack was used for sampling, but only stereomicroscope was employed for MP identification. The total removal efficiency reached 95.6% and 97.2%, respectively, after the secondary treatment and tertiary treatment. The membrane bioreactor system removed 99.4% MPs, discharging 0.5 particles L − 1 MPs. Fibers but not microbeads were identified as the major part in the effluent from two full-scale WWTPs.
How many people in Africa did not have sanitation in 2008?
Due to the increasing population, the urban population without sanitation services in Africa increased from 88 million in 1990 to175 million in 2008, and the number of people without access to drinking water climbed from 29 million in 1990 to 57 million in 2008 2. Thus, an extensive effort is needed for the last three remaining years for the achievement of the MDGs 16.
How is Dandora Oxygenation Pond treated?
In the stabilization ponds, waste water is treated through two processes: physical treatment and biological treatment . The Dandora Oxygenation Pond is a wastewater stabilization pond system with a capacity of over 80 000 m 3 /day 25. It is Nairobi's main sewage treatment system, which receives about 80% of wastewater generated from Nairobi city ( www.nairobiwater.co.ke/water_quality/?ContentID=7 ). The main process includes anaerobic ponds, facultative ponds, and maturation ponds (Fig. 2 ).
What are the challenges of waterworks in Africa?
Poor operation and maintenance is a challenge for WWTPs and waterworks. For some manufacturers in Africa, they cannot get applicable technologies to remove pollutants from their industrial wastewater due to limited available information and experiences. Some waterworks are facing challenges for the dosage of coagulants when the turbidity is too high or too low 4. For example, the turbidity of raw water in Nairobi can reach 5000 nephelometric turbidity units in rainy season due to soil erosion in the upper stream, while it is <10 nephelometric turbidity units during dry season 4. The variation of coagulant dosage is complicated for the operators in these waterworks. Coagulants imported from France, USA, and China, are used in African countries, and the selection of cost-effective coagulant is difficult in some cases. Another challenge for drinking water treatment in Africa is algae. Algae may consume more chemicals, clog filters, result in bad smell, and cause microcystin, which is toxic and hazardous to human health 45.
What are the challenges of stabilization ponds?
A serious challenge for stabilization ponds and lagoons is the heavy load of influent. The influent concentration is high due to insufficient pretreatment of industrial wastewater. One case in point is the Dandora WWTP, Nairobi, Kenya 21. We collected samples and found that the influent chemical oxygen demand and biochemical oxygen demand in the Dandora WWTP is 2030 and 1500 mg/L, respectively, while the average removal of organic pollutants is 70%. According to our investigation, the average removal efficiency of NH 3 -N, TN, and TP in Dandora WWTP is only 46, 36, and 16%, respectively. The effluent from the system is heavily colored due to algae.
What is the main source of water pollution in Africa?
Domestic wastewater is a major source of water pollution. Poor urban planning and rising population have resulted in illegal settlement and slums 17. It is estimated that 60% of the urban population in Africa is living in slum conditions, where sanitation services are poor, inadequate, and unreliable 1. For instance, Kibera, in Nairobi, is the second largest slum in Africa 18. Although the residents in Kibera account for 20% of the Nairobi population, this slum is traditionally looked at as an illegal settlement in Nairobi 2. Due to lack of sewerage collection system and wastewater treatment plants (WWTPs), most residents in this area have no access to sanitation, or just limited sanitation systems such as latrines and small-bore sewers 2 .
Why is water quality important in Africa?
The water quality in Africa is facing severe challenges. Improvement of water and wastewater treatment is of vital importance to achieve the MDGs. Currently available treatment methods of water and wastewater are often chemically, energetically, and operationally intensive, which might not be used in many places in Africa due to the lack of appropriate infrastructure 53. Thus, it is important to develop applicable water and wastewater technologies for African countries. Comprehensive efforts are needed. It requires contributions from all stakeholders: governments, non-government organizations, and private sectors. In consideration of the unique characteristics of Africa, it is of vital importance for the Africans to find their own way to protect water quality. Although it is important for African countries to get financial aid and technical support from the outside nations, it should be noted that the internal efforts are far more important than any external aids and assistance for safe water and healthy ecosystem in Africa.
Why are biofilms used in Africa?
Conventional treatment processes such as activated sludge and biofilms are used seldom in Africa due to lack of energy and financial resources. For instance, in Uganda, the National Water and Sewerage Corporation employs Conventional Sewage Treatment Works only at Bugolobi Sewage Treatment Works for Kampala City and one plant in Masaka Sewage Treatment Works ( www.nwsc.co.ug/about04.php ), while it applies stabilization ponds for the other sewerage treatment plants. The Bugolobi Sewage Treatment Works only covers 55% of the sewage produced within the Nakivubo catchment area, while the rest of the sewage goes into natural wetlands around Kampala without any treatment ( www.afdb.org/en/projects-and-operations/project-portfolio/project/p-ug-e00-008 ). Figure 1 is the Sirte City Wastewater Treatment Plant in Libya, where secondary treatment and tertiary treatment are adopted before the effluent goes into the Mediterranean Sea.
Where is waste practice common?
waste and medical waste, is a common practice in Africa [21].
How much of Bugolobi's sewage is covered?
plants. The Bugolobi Sewage Treatment Works only covers 55% of the
What are the causes of groundwater pollution in Kenya?
Industrial wastewater and pesticides lead to pollution of groundwater. Kisumu, Kenya Although ground water is easily available (ground water levels are 2 – 5 m from the soil surface), basically. the water supply in this area is still dependent on surface water, mainly because groundwater is.
What are natural wetlands used for?
diseases. Natural wetlands are used for wastewater treatment or
How do wetlands benefit society?
Considerable effort is now being directed towards rehabilitation of degraded wetlands and the construction of artificial systems to treat effluent and stormwater. At the same time, wetlands provide potential habitat for vectors or intermediate hosts (collectively referred to in this document as 'invertebrate disease hosts': IDHs), of parasites implicated in the transmission of such important diseases as malaria and schistosomiasis (bilharzia). The present review considers, for the 2 major IDHs (mosquitoes and schistosome-;transmitting snails), the type of habitat required by the water-;dependent life stage and the ways in which wetland degradation, rehabilitation and creation may affect the availability of suitable habitat. General practical measures for minimising pest species, particularly mosquitoes, are included. This review also highlights other issues that require research and testing in the South African context, including: the IDHs implicated in less well-;known diseases (both of humans and animals) and the control of mosquitoes and schistosome-;transmitting snails through biomanipulation. We conclude that in regions of the country where the diseases are prevalent there is the likelihood that wetland rehabilitation and creation could inadvertently encourage the IDHs responsible for transmitting malaria and schistosomiasis. Assessment of the potential risks and benefits of a proposed wetland modification needs to be undertaken in a holistic manner using an adaptive framework that recognises the critical need to balance human and environmental health. Possible ways of controlling IDHs both in an environmentally-; and socio-;friendly manner need to be investigated using a multi-;disciplinary approach engaging invertebrate biologists, health care officials, wetland scientists and also sociologists and economists.
How does urbanization affect wetlands?
Rapid urbanisation increasingly isolates and exerts pressure on natural wetlands, particularly in the fast-growing developing countries of the tropics, including those of West Africa. Constructed wetlands such as sewage treatment plants, may unintendedly offer wildlife protection due to prohibitive access control and limited use, thereby attracting wary and specialised waterbirds in otherwise heavily disturbed formally protected wetlands with less polluted waterbodies. We present data from a rapid survey on 1-year post-opening colonisation and use of waterbirds in a recently constructed 11 ha restricted-access sewage treatment plant, situated in Ghana’s capital, Accra. During November-December 2013 and January 2014, nine daily counts in each month produced an accumulated count of >4200 observations belonging to 26 species of waterbirds, including several important Afro-Palaearctic and intra-African migrants, hereunder ardeids, piscivorous divers, waterfowl and waders. The distributional patterns of waterbirds clearly reflected local foraging opportunities and water quality parameters in the system of 12 inter-connected waste stabilisation ponds. A nearby semi-natural wetland with cleaner waterbodies, but higher levels of human interference, supported fewer waterbirds, predominantly commensal gregarious species. Our data suggests that strict protection from disturbances outweighs possible negative implications attributed to mere pollution of waterbodies supporting various waterbird guilds, thus highlighting the potential importance of informally protected sewage treatment plants distributed in functional networks, as a complement to designated wetlands. We anticipate that establishing similar or larger plants jointly will improve sewage treatment and waterbird conservation in urban Ghana, and West Africa in general.
What are the Millennium Development Goals?
Sustainable access to safe drinking water and basic sanitation is an important part of the millennium development goals (MDGs). For most African countries, an extensive effort is needed for the last three remaining years for the achievement of the MDGs, especially in Sub-Saharan Africa. Current practices for water and wastewater treatment in Africa are insufficient to ensure safe water and basic sanitation. To address this challenge, joint efforts are needed, including transforming to green economy, innovating technologies, improving operation and maintenance, harvesting energy, improving governance and management, promoting public participation, and establishing water quality standards.
Why is tilapia fish used in wastewater treatment?
Because of its resistance to low oxygen concentrations, the farmed fish is sometimes used as a first step in treating wastewater. The mild, white meat of the tilapia fish, along with its low fat content and high protein, vitamin, and mineral content, has made it an increasingly common food choice globally. Additionally, as an herbivorous fish, ...
What is tilapia used for?
One United States aquaculture operation, Kent Sea Tech, uses a tilapia channel as the first stage of treatment for wastewater from its striped bass tanks. The tilapia consume 30% of the solids generated by the bass, becoming another cash crop in the process. A 2018 study that used tilapia tanks for wastewater polishing also showed high rates ...