Water Pollution And Prevention Control Environmental Sciences Essay

Combined sewer systems were designed to transport both storm H2O and surface H2O overflow through the same pipe to a sewerage intervention works before dispatching to the H2O organic structures. However, in times of heavy rain, the cloaca can go overladen, which could take to blow H2O endorsing up the system to deluge houses and metropoliss. Alternatively, the combined cloaca has outfalls, which act as force per unit area alleviation valves, called storm cloaca floods ( SSO ) or combined sewer floods ( CSO ) . ( Nicky Cunningham, Handout of Water Pollution Prevention Control ) On the other manus, CSOs discharge untreated sewage straight to H2O organic structures, which contains a great trade of pollutants like pathogens, suspended solids, foods, toxic affairs etc, being a major beginning of pollution to the environment.

In this assignment, I will foremost discourse the function of the CSO in combined sewage systems, and their impact on the environment, every bit good as the factors that increase these impacts. Furthermore, I will present the options available now for cut downing the environmental impact of storm floods and the advantages and disadvantages associated with these options. Furthermore, I will give my suggestions on the practical steps needed achieve the greatest environmental benefits.

Role of CSOs

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!

order now

Combined sewer systems were designed to transport both storm H2O and surface H2O overflow through the same pipe to a sewerage intervention works before dispatching to the H2O organic structures. However, after the heavy rain, the volume of sewerage is frequently overloading the capacity that the intervention works can manage. This may take to blow H2O endorsing up the system to deluge houses and metropoliss. At that clip, combined cloaca floods ( CSO ) occur to stop up this state of affairs to supply an exigency issue for the combined sewerage straight to the H2O organic structures. For that ground, we have to acknowledge that CSO plays a critical portion of our sewage substructure. On the other manus, CSOs discharge untreated sewage straight to H2O organic structures, which may incorporate a great trade of pollutants like pathogens, suspended solids, foods, toxic affairs etc, being a major beginning of pollution to the environment and public wellness, which I will speak about in the following portion.

Impact on environment

Because CSOs discharge non merely storm H2O, route run off, but besides untreated domestic, commercial, industrial sewerage into having H2O organic structures, it may incorporate a great trade of contaminations including floatable affairs, organic affairs, foods and microbiological pollutants etc. Series of instance surveies can function to represent these emanations. “ In Northampton, England it was found that the entire mass of BOD emitted from CSO over a two twelvemonth period was about equal to the mass of BOD emitted from the secondary sewerage intervention works wastewater. And that the mass emanation of suspended solids ( SS ) in CSO was three times that of the secondary wastewater. In Buffalo, New York a survey concluded that 20 to 30 % of the DWF solids settled in the combined cloaca which was later flushed and bypassed during high-velocity storm flows. “ ( Field, R. Storm and Combined Sewer Overflow: An Overview of EPA ‘s Research Program ) If CSOs occurs often, it can do a assortment of inauspicious impacts on the quality of having H2O organic structures and the environment.

First, CSOs have an inauspicious impact on the aquatic home ground.

As mentioned above, big measures of foods may be discharged to the H2O, which cause the bloom the algae, and so do the eutrophication. In that instance, it will take to the O depletion and fish putting to deaths. Otherwise, alterations of the H2O temperature and turbidness, emanation of SS, BOD will besides endanger the aquatic home ground.

Second, quality of bathing Waterss is affected near the oral cavity of river by having assortments of organic affairs and toxic affairs from the untreated sewerage. This may do the diseases of people, even the stopping point of the beach. In theory, the CSOs could dispatch 3 times during the bathing season ( May to September ) , which is an acceptable frequence, but the world is ever non as expected. The hazard to public depends on the grade of human exposure, particularly higher for the usage as recreational H2O.

Third, the shellfish country will be influenced by the sewerage discharge to a limitation. Shellfish countries are usually located in the estuary, which may besides be affected by the CSOs. Because of the bacterial degrees of the untreated sewerage, the safety of shellfish Waterss and the crop are threatened to a big grade. In Long Island, New York storm H2O overflow was identified as the major beginning of bacterial burden to marine Waterss and the indirect cause of the shutting of about 1/4 of the shellfish country. ( Field, R. Storm and Combined Sewer Overflow: An Overview of EPA ‘s Research Program )

In add-on, the aesthetic jobs will besides be caused by the CSOs. CSOs may dispatch floatable affairs and some solids to the H2O organic structures, which may be washed to the beach, doing an image of dirty and turbid. Even worse, these affairs may bring forth smell and foul the ambiance at that place. All these will interfere with the aesthetic and agreeableness usage of the H2O organic structures.

Similarly, CSOs will potentially menace the imbibing H2O quality with the high content of bacteriums, pathogens, toxic affairs and other pollutants, which are evidently affect human wellness.

Otherwise, ill designed, maintained and inefficaciously operated CSOs, every bit good as the force per unit areas from the clime alteration, urban development and population growing will increase the impacts of CSO discharges on the receiving H2O organic structures.

Options of CSOs pollution control

As for such a great trade of inauspicious impacts on the receiving H2O organic structures, and the demand of the statute law from Urban Waste Water Treatment Directive ( 91/271/EEC ) , Bathing Water Quality Directive ( 76/160/EEC ) , Shellfish Water Quality ( 79/923/EEC ) and the Habitats Directive ( 92/43/EC ) etc. , many communities have taken actions to command the pollution from CSO and better the quality of H2O organic structures. Harmonizing to the Urban Waste Water Treatment Directive91/271/EEC:

a-?limitation of pollution of having Waterss due to ramp H2O floods

‘ ( 1 ) Given that it is non possible in pattern to build roll uping systems and intervention workss in a manner such that all waste H2O can be treated during state of affairss such as remarkably heavy rainfall, Member States shall make up one’s mind on steps to restrict pollution from storm H2O floods. Such steps could be based on dilution rates or capacity in relation to dry conditions flow, or could stipulate a certain acceptable figure of floods per twelvemonth. ‘ ( The Urban Waste Water Treatment Directive ( 91/271/EEC ) , Article 3 and Annex )

Here I will present the chief options of CSOs pollution control briefly by giving the advantages and disadvantage of each.


Screens are set for forestalling the largest objects from being released into the H2O organic structures straight. They have non been common in the past partially because of the disadvantages of excess energy and care costs. However, as the recent concern on aesthetic pollution, screens are considered as a more serious option now. They are an effectual and economical option for taking solids and floatable affairs from CSOs. However, as a physical intervention procedure, screens are non plenty, extra intervention will be required. In add-on, the clean of the screens is still a job waiting for work outing.


In-line storage allows a greater volume of wastewater to be retained within the system, which can so be passed frontward to the STW for intervention when the period of rainfall has ended. The advantage of storage is to maximise the capacity of cloacas and cut down the pollutants dispatching to having H2O so as to cut down the impact on environment. On the other manus, the disadvantages are inevitable. We must see the hazard of sewerage endorsing up to the houses and metropoliss if overload the affordability of storage armored combat vehicles. In add-on, building such immense storage armored combat vehicles and keeping need a great trade of operating and capital outgo.

III.Sewer separation

Separating the combined systems into distinguishable healthful and storm H2O systems is another option of CSO control. It is taking for discharge the storm H2O straight to the outfall into the H2O organic structure. The advantages of sewer separation are reasonably obvious. It will wholly work out the job of healthful sewerage endorsing up to the houses and metropoliss. Similarly, it will cut down even extinguish the inauspicious impact of untreated healthful sewerage discharge to the H2O. In contrast, the disadvantages of sewer separation are important. It is considered unrealistic as the high cost and low feasibleness. Furthermore, building new cloacas or reforming the old 1s will do break of occupants and other sorts of pollution like noise etc. Anyhow, in my sentiment, sewer separation may be hard to carry through, nevertheless it is the most effectual and options to work out the jobs from the root.

IV.Treatment of Storm Overflows

As I have mentioned before, testing is non plenty as a physical intervention procedure. We need moreover intervention of storm H2O flood, which is another option of CSOs pollution control. The intervention could use chemical, biological steps that are the same as the STW usage. Some physical and environmental steps like pools and wetlands could besides be applied. In that instance, the bacteriums, the pathogen, the toxic affairs etc. contained in the saw sewerage can be treated efficaciously and the impact on H2O organic structures will be mitigated. The application of pools and wetlands will besides increase the biodiversity and aesthetic consequence as good. However, due to the big and incomputable volumes involved, the cost and energy demand will be really high, every bit good as the C emanations.

Meanwhile, there are still some other options, for case, the public presentment of the bathing H2O quality in the bathing season, beginning control to cut down the pollution of storm overflow from the beginnings, regular care of the system and efficaciously proctor, being used and contributed to the control of CSOs pollution. We know that CSOs inauspicious impact can non be eliminated ; nevertheless, it can be mitigated by using appropriate steps. In the following portion, I will give some suggestions on the practical steps need to accomplish the greatest environmental benefits.


Although big attempts to better the public presentation of CSOs have been made, there are still far more to make particularly under the higher demand of ordinance and wellness criterion of H2O quality. From my respective:

In the first topographic point, we should better the perceptual experience of public through instruction. I think better the H2O quality and cut down the inauspicious impact of CSOs is non merely the duty of operators but besides of ourselves. Our public can assist. Environmental regulators and H2O companies should lend to educating people particularly non-flushable affairs. I am still impressed by the image of the screens at the outfall with a batch of healthful affairs like rubber. Therefore, advancing apprehension and engagement in environmental issues through instruction is important. Remember that what goes down drains may travel into the H2O straight ; we can and should assist maintain the H2O clean.

Similarly, heightening the cooperation among the environmental regulators, H2O companies and other communities is more important. Environmental regulators should heighten the ordinance of CSOs discharge and fasten the guidelines for CSOs. The H2O companies should take duty to increase the frequence of monitoring and keeping the substructures of CSOs and invest to cut downing the sum of times that CSOs spills. Meanwhile, the H2O companies should better their cognition of operation and direction of CSOs harmonizing to historical and farther surveies. In drumhead, all the communities should pass on and hold with each other instead than being in struggle. Our lone struggle should be with the sewerage.

In add-on, beginning control could be a more practical and effectual option to cut down the pollution at beginning. The surface H2O overflow may be possible to do betterments by altering land direction patterns, halting illegal discharges or supplying some intervention steps. In that instance, the natural sewerage flow into the CSOs pipes could hold a low content of contaminations.

Furthermore, the SUDs should be promoted to better the surface H2O quality. The SUDs are being set up as best drainage pattern now and they can assist to cut down the inauspicious impacts that CSOs take on the H2O class.

What ‘s more, the engineering invention could be one of the considerations. Environmental regulators and H2O companies can promote the new engineering of the CSOs control by supplying fiscal encouragement.


Equally far as I am concerned, the CSOs stop up the state of affairs of healthful sewerage baking up to the houses ; whereas, sewage discharges from CSOs cause earnestly inauspicious impact on having H2O organic structures on bathing H2O, shellfish H2O, portable H2O, aquatic home ground and human wellness. Consequently, extinguishing or cut downing CSOs impact is an tremendous fiscal challenge every bit good as the engineering invention. Many communities including environmental regulators and H2O companies have studied and contributed to the control schemes of efficaciously cut down their associated environmental and wellness hazards. These schemes include screen, storage, sewer separation, intervention of storm floods, public presentment and spill frequence decrease etc. After measuring these options available for CSOs pollution control, we found that the cost and feasibleness are the chief considerations of each option. As a consequence, bettering the public presentation of CSOs and seeking for steps more economical and effectual becomes more important under the circumstance of progressively rigorous environmental criterions, increasing population, speedy urbanisation and clime alteration. All in all, we should lend to develop the sustainable, operable and low-cost ways to track CSOs jobs.


I'm Ruth!

Would you like to get a custom essay? How about receiving a customized one?

Check it out