Publish Time: 2022-12-09 Origin: Site
Wastewater treatment equipment is suitable for wastewater treatment in dental hospitals,dental clinics,community clinics,laboratory departments,hospital operating rooms and other places.The wastewater produced by these institutions contains a large number of pathogens such as bacteria and viruses,and cannot be discharged directly into the municipal drainage network without any treatment,equipment is to disinfect and sterilize the raw sewage to make it meet the wastewater discharge standard.
Relatively simple wastewater treatment technologies can be designed to provide low-cost sanitation and environmental protection while gaining additional benefits from water reuse.These techniques use natural aquatic and terrestrial systems.They are used in many places throughout Latin America and the Caribbean.These systems can be divided into three main types.Mechanical treatment systems use natural processes in artificial environments,often when suitable land is not available to implement natural system technologies.Aquatic systems are typified by lagoons;facultative,aerated and hydrologically controlled release (HCR) lagoons are variations of this technology.In addition,lagoon-based treatment systems can be supplemented by additional pre-or post-treatment using constructed wetlands,aquaculture production systems,and/or sand filtration.They are used to treat all kinds of wastewater and function in all weather conditions.Terrestrial systems utilize nutrients from wastewater;plant growth and soil adsorption convert bioavailable nutrients into less available forms of biomass,which are then harvested for various uses,including methane gas production,ethanol production,or cattle feed supplement.
Mechanical Treatment Technologies
Mechanical systems utilize a combination of physical,biological and chemical processes to achieve treatment goals.Mechanical treatment techniques use essentially natural processes in artificial settings,using a series of tanks along with pumps,blowers,screens,grinders and other mechanical components to treat wastewater.Wastewater flow in the system is controlled by various types of meters.Sequencing batch reactors (SBR),oxidation ditches,and extended aeration systems are all variations of the activated sludge process,which is a suspended growth system.In contrast,the trickling filter solid contact process (TF-SCP) is an attached growth system.These treatment systems are effective where land is valuable.
Aquatic Treatment Technology
Facultative lagoons are the most common form of aquatic treatment lagoon technology in use today.The water layer near the surface is aerobic,while the bottom layer,including sludge sediments,is anaerobic.The middle layer is aerobic near the top and anaerobic near the bottom,constituting the facultative zone. Inflatable lagoons are smaller and deeper than facultative lagoons.These systems evolved from stabilization tanks when aeration was added to counteract odors from septic tank conditions.Aeration devices can be mechanical or diffused air systems.The main disadvantage of lagoons is the high solids content in the effluent,which can exceed 100 mg/l.To counteract this,Hydrograph Controlled Release (HCR) lagoons are a recent innovation.In this system,wastewater is discharged only when the stream flow is sufficient to prevent water quality from deteriorating.When stream conditions prohibit discharge,wastewater accumulates in storage lagoons.Constructed wetlands,aquaculture operations and sand filters are often the most successful methods of purifying lagoon wastewater.These systems are also used with more traditional engineered primary treatment technologies such as Imhoff tanks,septic tanks and primary clarifiers.
Their main advantage is to provide additional treatment beyond secondary treatment when required.In recent years,constructed wetlands have been used in two designs:systems using surface water flow and systems using groundwater flow.Both systems utilize the roots of plants to provide a substrate for the growth of attached bacteria that take advantage of the transfer of nutrients and oxygen present in the effluent.Bacteria do most of the work in these systems,although plants take up some nitrogen.Surface water systems are closest to natural wetlands.Typically,these systems are long,narrow basins,less than 2 feet deep,with aquatic plants such as reeds (Scirpus spp.) or cattails (Typha spp.).Shallow groundwater systems use a medium of gravel or sand approximately 18 inches deep to provide a rooting medium for aquatic plants through which wastewater flows.Aquaculture systems are characterized by the types of plants grown in wastewater collection ponds.These plants are usually water hyacinth (Eichhornia crassipes) or duckweed (Lemna spp.).These systems are basically shallow pools covered with floating plants that hold wastewater for at least a week. The main purpose of plants in these systems is to provide a suitable habitat for bacteria,thereby removing the vast majority of dissolved nutrients.Sand filters have been used in wastewater treatment for at least a century in Latin America and the Caribbean. Two types of sand filters are commonly used: batch and recirculating. Their main difference is the method of wastewater application.Batch filters are filled with wastewater and then completely drained before the wastewater is used again.In contrast,recirculation filters use a pump to recirculate effluent to the filter in a ratio of 3 to 5 parts filter effluent to 1 part raw wastewater.Both types of filters use a 2 to 3 foot thick layer of sand beneath a closed perforated or open joint pipe collection system in graded gravel. Water is biologically treated by epiphytic flora associated with sand and gravel particles,although some physical filtration of suspended solids by sand and some chemisorption of sand surfaces play a role in the treatment process.
Land Processing Technology
Land-based treatment systems include slow surface runoff,slow subsurface infiltration,and fast infiltration methods.In addition to wastewater treatment and low maintenance costs,these systems can generate additional benefits by providing water for groundwater recharge,reforestation,agriculture and/or livestock grazing.They depend on physical,chemical and biological reactions on and in the soil.Slow surface flow systems require vegetation,both to absorb nutrients and other pollutants,and to slow the flow of sewage through the surface to ensure maximum contact time between sewage and plants/soil.Low-velocity subsurface infiltration systems and rapid infiltration systems are "zero discharge" systems that rarely discharge effluent directly into streams or other surface waters.Each system has different limitations on soil permeability.While slow surface runoff systems are the most expensive natural systems to implement,their strength lies in their positive impact on sustainable development practices.In addition to treating wastewater,they generate economic returns through the reuse of water and nutrients to produce marketable crops or other agricultural products and/or water and feed for livestock.The water can also be used to support reforestation projects in water-scarce areas.In slow-velocity systems,primary or secondary wastewater is applied at a controlled rate to vegetated surfaces of moderate to low permeability through sprinklers or by flooding in furrows.Wastewater is treated through filtration,adsorption,ion exchange,sedimentation, microbial action,and plant uptake as it passes through the soil.
Vegetation is an important part of the process to extract nutrients,reduce erosion and maintain soil permeability.A surface flow system is a land-applied treatment method in which treated effluent is ultimately discharged into surface water.The main advantages of these systems are low maintenance costs and low skilled manpower requirements.Wastewater flows intermittently across the top of terraces built on extremely low-permeability soil and allowed to flow in sheets along the vegetation surface to runoff collection channels.Treatment,including denitrification, is mainly achieved through sedimentation,filtration and biochemical activities as wastewater flows over the vegetation surface of the terraced slopes.Loading rates and application periods are designed to maintain active microbial growth in the soil.The speed and length of application are controlled to minimize the occurrence of severe anaerobic conditions,and rest periods are required between applications.The rest period should be long enough to prevent surface water accumulation,but short enough to keep the microorganisms active.