Water and Silt Recycling Problems and Methods

by Jason Shaw
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  1. Introduction

Water recycling is one of the most radical findings that industrialization has perhaps found irreplaceable. In the early days of human society, the water used was simply disposed of, before water shortages threatened the continuation of essential industrial and other processes. This is because the availability of fresh water is always nearly low and resources require supplementation (Beddow, 2010, p1). The realisation of the value of resources such as water and the implications of ignoring this reality was a basis for the formulation of policies at the level of social governance (Williams, 2005, p130). Like other useful resources, waste water was to be treated with caution; it was recycled to replenish the limited natural supplies and save on cost. As the treatment of unwanted solid waste has other benefits, recycling of waste water became rapidly widespread among environmentalists. Water is evidently an invaluable advantage in many commercial industries, where it is used either directly or implicitly for various purposes. Domestic use often reflects a large amount of expenditure on water, a resource that tends to be restricted in quantity.

Considering usage and recycling of waste water cannot perhaps be illustrated without incorporation of major applications in ancient or modern industrial usages. According to Rae (2011, p1), the UK can be regarded as the birthplace and cradle of the most important revolution that changed human history; the Industrial Revolution. For the UK, several types of recycling projects have been carried out, while top flight commercial activities have been embarked by various companies. In view of the importance of waste water and silt recycling, the UK has been able to made huge strides in commercial and domestic solid waste disposal, agriculture and land reclamation among a host of several other applications. To facilitate and coordinate waste handling and recycling activities, the UK has adopted regimes such as Best Practicable Environmental Option (BPEO) which acts as a pointer of how seriously recycling can be taken. Contained in this study are examples that describe the UK’s water recycling efforts in unravelling the importance of performing waste water and silt recycling and management.

Water and Silt Recycling Problems and Methods

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  1. Water Treatment

Water is increasingly becoming a rare and insufficiently supplied resource, especially on a planet facing serious climate change issues. According to Rae (2011, p1) several techniques have been devised for the treatment of waste water so that it can be recycled to facilitate a safe reuse. According to Wescott (2010, p32), the most pressing topics in the recent environmental debate are water and climate change. Almost all world countries, even those close to the ocean and other massive water bodies face water and climate change challenges in form of unprecedented risks. Therefore, water treatment has become a genuine source of solution to the problems that call for water adequacy in different categories of use. In particular, industrial use is essential to the solutions provided by treating water using some of the techniques available. Depending on the quality of the waste found in the water, some of the types of waste water typically used include green water, grey water and black water.

  • 2.1 Problems of Water Treatment

There are several concerns that stand in the way of a successful water treatment, since purity levels of the treated water seems to be questionable. Regarding the safety of waste water passing through treatment processes, it is unquestionable that such water is unpalatable and not recommended for human or animal consumption. If domestic usage for such water remains restricted to only a few applications, it then raises questions on the inclusiveness of the treatment techniques of water treatment for all human needs. According to Hein (2005, p2), two sources of waste water constitute the largest volume of treatment water in a typical European case such as that of Germany. One of the sources is domestic and urban waste water while the other is industrial water residues.

Perhaps the most potent problem associated with water treatment systems touched on the chemical content of waste water that is usually difficult to be completely eliminated using elementary water treatment techniques. Presence of certain industrial chemical elements that require complex separation techniques may hinder complete purification of waste water. In case of application of such techniques, it could be very expensive to incorporate them in the treatment plants due to several cost factors. However, modification of the techniques could be used in future waste water treatment.  Besides environmental pollution risks involved in the release or reuse of such treated water with chemical constituents, living systems also face poisoning risks from such waters.

The other serious problem posed by the treatment systems for waste water is the residual presence of pathogenic microorganisms in the final treated water. It is difficult for a waste water treatment system to get rid of all microbial presence in the water. Conventional antimicrobial can be incorporated in such a system only if several expensive modifications are made, including enclosure of the system. According to the European Union’s Eurostat (2010, p1), several European countries have adopted sewage treatment to sustain water demands in several sectors of their economy. To illustrate this fact, the UE gives figures of total waste water treatment as applied by member states; Netherlands’ treatment stands at 99 per cent, Germany at 95 per cent, Italy at 94 per cent and Switzerland at 97 per cent.

  • 2.2 Methods of Water Treatment

Depending on the amount of contamination sustained by the water upon usage, various techniques have been designed. Different levels of treatment that can be achieved depending on the amount of purity expected and purpose of the procedure. The levels, as defined by the complexity of processes undertaken include; primary, secondary, tertiary and specialized processes. As complexity increases in the treatment processes, purity increases accordingly. In the EU, Austria, Germany, Sweden and the Netherlands comprise of top tertiary treatment access. In view of the relevant statistics given by the EU referring to different periods, these countries had more than 80 per cent connectivity in terms of tertiary treatment services. The most basic treatment delivers sewage sludge which is widely used in agriculture among several European states.

    • 2.2.1 Sludge Treatment Methods

Sludge obtained from waste water particularly that which emanates from industrial processes or from residential end-usage sewage can be processed using a variety of techniques. The main aim of such techniques is to sieve free waste using simple techniques in conjunction with the application of complex chemical separation techniques to separate chemically bound elements. After removal of both simple and complex wastes from such industrially and sewage contaminated water, it can be put to safe usage. Besides, the sludge obtained can be processed to eliminate possible harmful contaminants and subsequently applied in useful projects (Williams, 2005, p326).

 The basic technique involves decantation of the large particles of sludge, which is done by allowing settling of the sediment in the settling tank. Enough time is allowed while physical disturbance of the tank is avoided. The two portions of the waste water are then gently separated to obtain the liquid and solid (semi-solid) as distinct as possible. This type of sludge obtained after settling of the waste water is referred to as raw sludge (Williams, 2005, p105).

Another treatment technique uses the isolated raw sludge in a biological process that involves decomposing procedure in a special chamber. Usually, anaerobic bacteria species decompose the raw sludge and enable further liquid and solid separation. A huge volume of the solid waste is liquefied which translates to a smaller volume of the sludge when compared with the initial volume (Williams, 2005, p350). Upon decomposition, the end product sludge is usually referred to as digested sludge, which has a relatively low waste content. Chemical treatment of the sludge may be used to completely eliminate wastes and use the sludge in agricultural projects due to its rich minerals content. In addition, the sludge can be burnt using combustion technique that eliminates the waste. It is also possible to burry the sludge for better disposal. Direct modified physical procedures may be applied on the sludge to obtain electricity and gas. The main precaution that these processes ensure is environmental impact of the sludge, such as chemical and heavy metal content reduction, as well as pathogenic microorganism removal.

Alternatively, the liquid portion of the separation containing suspended finer wastes is subjected to various chemical or biological treatments. The waste is usually flown in a field of special surface plants that are capable of extracting more particles from the liquid, which is completely separated into clean water at the end of the process. In more advanced industrial processes, this liquid may be separated in columns that apply complex separation techniques that give pure end product of water and sludge at a higher efficiency but in at a higher cost.

Some sludge contents such paints and batteries incorporate heavy metals into the disposal systems, presenting a very serious threat to living systems. Organophosphates and organohalogens as well as other chemicals such as chlorides, mercury, metals, fluorocarbons, nitrates, radioactive compounds may find their way into the systems affecting both the atmosphere and biosphere causing serious environmental and ecosystem problems (Williams, 2005, p237). Determination of the total suspended solids is important at the beginning of the treatment, since various chemical components might require application of different techniques. Some of the techniques used to isolate chemicals from the waste water are chemical techniques such as chemical substitution and displacement techniques.

  1. Problems Associated with Silt

According to various terminologies referring to the accumulated solid particles when waste water settles or is separated. Silt deposition in any water system acts as a hindrance to the flow of water hence poses a threat to the resources availed by such water. For instance, rivers become shallow due to the activity of silt deposition which effectively reduces the volume of water that can comfortably be supported by the banks. Removal of silt deposited by useful rivers has been a major reclamation intervention where river flow can be regained through maintenance of the usual depth hence the volume (Sanchez, 2010, p1).

In addition, silt deposition presents a serious headache to major hydro projects such as dams since the sediments contained in the rivers sink to the bottom of the dam once enclosed (internationalrivers.com, n.d, p1). It is particularly a pressing challenge to projects involving very large reservoirs created from river waters. The total amount of deposit expected from such a project can be calculated to give a figure referred to as Trap Efficiency (T.E). In comparison to other smaller projects, very large dams give a T.E figure approximate to unit, which implies that the level of silt deposition is significantly huge. Within a short duration of time, the dam is usually in need of servicing which includes removal of the silt deposits. The threat posed to water dams is therefore in the fact that the effective volume of water held by the dam continues to reduce with continued deposition. Although the factors that influence the rate of silt depiction vary from one place and project to the others, storage capacity continues to shrink across projects. According to internationalrivers.com (n.d, p1), silt deposition is perhaps one of the most potent technical challenges that face the dam industry.

According to Scudder (, p229), river basins are likely to be completely changed when the rate of silt deposition is high causing such modifications as deltas. The author also holds the opinion that continued deposition is tantamount to ecological instability threatening life forms in such aquatic habitats as deltas. Implications of modifications of waterways for instance, results in extra dredging costs (Salcombe Harbour Board, 2010, p1).

In other water supply projects, silt causes clogging that result in encrustation of the water systems (Clarke, p19). The author notes that the removal of silt in such systems is particularly difficult since specialized mechanisms are needed for the cleaning.

  1. Silt Applications

Silt obtained from dredging of water bodies is usually put into use, mainly classified under three classes of usage. These classes of usage include; modified usage, agricultural usage, product usage as well as in environmental usage (US Military Corps, 2006, p1). Some other beneficial skills that individuals can make where others fail include the utilization of water whose silt index is considered too high and almost impractical to purify. According to Suez Environment (2006, p2), organizations such as Ondeo Industrial Solutions have been able to offer technology which can enable treatment of silt water for basic uses.

  • 4.1 Agriculture

According to Army Corp (2006, p4), there are different components of sediment deposits for instance gravel, sand, consolidated clay, rock mixture and silt. Among these types of sedimentation, silt is most important to agricultural activities enhancement such as crop cultivation, aquaculture and top soil for various specialized crop care. Some of the dredge components require further enhancement before application in agricultural activities. However, most of dredged material offers quality supplements for top soils for cultivation of food crops. In food crop cultivation, caution must be exercised to avoid contamination of the food products. Handling the dredged material during cultivation of food crops may be enhanced by application as a special layer which can be pumped under the ordinary planting soil without direct contact with the crops.

Some treatment of silt may be necessary in order to be used as agricultural soils. According to Army Corp (2006, p5), some of the preparations that may be applied to dredged material for use in agriculture include dewatering. Removal of certain components of soil or addition of others may be necessitated by the nature of silt source in relation to its capacity to support crop growth. Salty silt, for instance could require certain modification to enable growth of crops from non-saline conditions.

Organic fertilizers are obtained from treatment of waste water after processing which reduces the amount of harmful microbial cultures.

  • 4.2 Energy and Economic Benefits

According to Ilex Energy Consulting Group (2005, p5), the UK can reliably depend on production of energy from the country’s over 300 million tones of refuse deposited each year. In a report to the Department of Trade and Industry, the refuse energy recovery projects in the country could be enhanced from 2 percent in 2005, to facilitate extraction of much needed benefits of energy from waste.

Silt can be utilized for commercial benefits such as by isolation of gravel washing component for purposes of purification of water for drinking (Parriaux, 1995, p54). According to the author, disposing of such components of silt can be hectic and could result into environmental problems. Such applications not only provide a channel for environmental conservation but also offer alternative for commercial activities. The author also found out that this form of silt can be used in the creation of water-tight containers for contaminant housing. Some components of silt also contain some valuable constituents which can be isolated for sale as precious resources such as quartz (Assallay et al, 1998, p61). According to the author, building materials such as bricks can also be obtained from silt.

  • 4.3 Environmental Benefits

Silt and other dredged materials can be used in the enhancement of wildlife habitats such as upland habitats. According to Army Corp (2006, p6), it is possible to recreate lost habitats lost by adverse environmental conditions such as drying and submersion. To achieve such attempts, dredged material is placed in appropriate areas to facilitate wildlife such as birds to rebuild their lost habitats. Reproduction sites can be created for certain types of wildlife by use of soft layers of silt that can from nests and improved using cobbles and shells. Creation of enhanced habitats can produce environments as close to natural habitats as creatively as possible.

Fishery habitats are one of the most important environmental applications that silt treatment products can be used to achieve. Army Corp (2006, p7) states that mounding silt and other dredge products can facilitate creation of habitats that improve fishery ecology. Further improvements to the created fishery habitat can be achieved by use of sea grasses and other naturally existing flora and fauna.

Dredged material is also useful in reclamation of deteriorating wetlands, by modification of their remains to achieve an original or natural characteristic. Wetlands restoration using silt and other dredged material s assumed to achieve the natural conditions such as those availed at the riverbed and lakesides. The type of oil from which the dredging is done as well as the water type determines the application in creation of a rehabilitation project for a lost wetland. Regaining a lost wetland is not an easy project since processes such as layering of dredged material requires delicate and keen geological and ecological proficiency. Growth of native vegetation to support life-forms in the regained habitat is a tricky ecological encounter that demands prowess.

Conclusion

Water and energy are some of the basic necessities of an economy and need to be in plenty supply for growth to occur, despite the fact that most their sources seem to be irreplaceable. It can therefore be interpreted as improper conduct for any leadership to rely solely on such sources of vital resources in a modern world. To ensure sustainability in supply of these and several other resources, it becoming increasingly realistic to source for extra means of supply, with recycling being the most applicable. Wastewater recycling to obtain water is perhaps one of the best illustrations of how vital resources can be replenished to supplement to unreliable natural sources.  Solid waste management must be done in tandem with the growth opportunities created by the economy, but beneficial disposal must first be explored to ensure maximization of utility for the scarce resources. Composting the waste water acts as huge environmental benefit due to the complete elimination of possible health and habitat threats opposed by the wastes. However, alternative disposal points at a better use of such wastes with creation of extra benefits.

The realization of benefits that waste products have and can present to the economy is a timely idea to the technologically advanced world. It is perhaps an area that world economies need to invest in with the seriousness it deserves, since the benefits by far outdo the costs incurred in such projects. Venturing into such projects will not only act as a source of income and resources but will also go a long way in support of a green world. There is a marked lack of participation by the relevant stakeholders into the topic, which should act as an indicator of how much input is needed. Both the public and private sectors need to pull together towards realization of a beneficial waste disposal.

Modern innovations should be directed at achievement of extra benefits from the manner in which waste disposal is handled. Resources must be handled with extra caution to avoid wastage since the technology level of the present day has considerably increased to allow for record efficiency levels. Environmental friendly alternatives must continually be explored in order to safeguard nature and its capacity to support life for a little longer than it would without such caution.

References:
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