Organic wastes, Sewage and the Marine Enviroment

Question 1

What are some organic wastes (nature of sewage)

Answer 1

• human bodily wastes from our domestic toilets and bathwater
• food waste from kitchen sinks
• agricultural waste (in substantial quantities where factory farming is practised)
• food processing wastes from slaughter houses, freezer plants, pulp from sugar beet factories etc
• brewing and distillery wastes
• paper mill and chipboard factories that produce wood fibre wastes
• oils and diesels from road run-off

Question 2

Goive some non - organic wastes that come from sewers.

Answer 2

Non-organic waste from sewers

• sanitary products, barrier contraceptives etc.
• drugs and pharmaceuticals
• domestic cleaning chemicals
• heavy metals and chemicals from industrial discharges
• Pesticides and fertilizers from run-off from agricultural land

Question 3

To license effluent discharge you need to know ;

(1) Bacterial Oxygen Demand

Answer 3

Typically, urban sewage has a Biochemical Oxygen Demand of 500 mg per litre (beer has a BOD of 70,000 mg l-1)

Oxygen saturated water has the capacity to deal with a BOD of 8.0-8.5 mg 1-1

Therefore each litre of sewage needs the oxygen from 63 litres of water.

As sewage is largely organic carbon based one solution is dispersion, the only medieval method.

Modern day canal’s and rivers receive a whole range of pollutants and their carrying capacity must be considered.

BOD technique – measure oxygen at the start of a given period, and at the end of a given period you can see the oxygen usage rate – can see how much oxygen is required for that given effluent and therefore how much water needs to be flushed through.

Question 4

To license effluent discharge you need to know ;

(2) mixing zones

Answer 4

• Knowledge of the circulation and hydrodynamics of the receiving waters is required, understanding flow and mixing rates.
• Immediately after discharge it will be at its thickest, and its conc will decrease from the point source of effluent discharge.
• As bacteria take time to get going, there is a lag between input and peak oxygen demand
• Thus mixing should ensure that the combination of re-aeration and dilution prevent the oxygen “sag” falling too low.
• If the distance between two discharge points is too small in distance or time oxygen levels can be dangerously reduced.
• Rates of oxygen utilisation increases as bacteria multiply, and a fitted curve will lag behind oxygen utilisation curve. The critical point is the lowest point of oxygen in the process, too low oxygen levels would cause complete anoxia.

Question 5

What are the immediate impacts of sewgae in aquatic systems

Answer 5

oxygen depletion and the imput of nitrates

Question 6

Immediate impacts - describe oxygen depletion

Answer 6

• Oxygen depletion in the water body results in anoxia and mortality of biota
• In river systems, typically the first indicators are fish
• Bacterial degradation of biota remains causes further oxygen depletion, inducing a positive feedback mechanism
• Later on in the process anaerobic products are present anaerobic breakdown – toxic end products
• In addition to a biological oxygen demand, if the sewage contains reduced compounds these may be chemically oxidised, causing an additional Chemical Oxygen Demand (COD) (draws oxygen from the system)

Question 7

Immediate impacts - describe input of nitrates

Answer 7

• All of the elements that are required for photosynthesis (nutrients are the limiting factor)
• Average person produces
  
  • 9 g Nitrogen and
  • 2 g Phosphate per day as faeces
  • As bacterial breakdown of sewage proceeds these are released in forms readily assimilated by plants
• Detergents
• Agricultural run-off of fertilisers
• Atmospheric inputs rain-runoff from atmospheric sources can be as high as 20 kg per hectare per year.
• traffic, intensive cattle breeding

Question 8

What are the effects of eutropication?

Answer 8

• Disruption of the normal commuity composition
• Increased turbidity
• Bacterial decay of phytoplankton leads to oxygen depletion
• Nutrient leading may increase the prevalence or severity of diseases of a variety of organisms.
  
  • Mechanisms are not well understood.

Question 9

Eutropication effects describe disruption of normal community compositon.

Answer 9

Blooms are a natural phenomena

Anthropogenic nutrients may increase bloom frequency, alter seasonal timing/duration or alter the species composition/balance

Usually due to differential competitive abilities in the face of N limitation

Particularly threatening to areas that rely on clear waters

Question 10

Eutropication effects describe increased turbidity.

Answer 10

Threatening or impactful in water that are naturally very Oligotrophic (nutrient poor).

Tropical waters rely on the nutrient lacking transparency of the water.

Question 11

Eutropication effects - describe bacterial decay of phytoplankton leads to oxygen depletion

Answer 11

In extreme cases can lead to anoxia

estuaries and bays with limited flushing

fjords and sea lochs

adjacent to aquaculture systems

Baltic, Kattegat, Gulf of Mexico and East China Sea

Question 12

jhow may sewage impacts affect coral diseases?

Answer 12

Temperature stress (e.g. Bruno et al., 2007; Sokolow, 2009)

Alterations of fish abundance and functional diversity (e.g. Raymundo et al 2009)

High coastal human population (e.g. Abey at al., 2011)

Proximity to algae (e.g. Vega Thurber et al., 2012)

Nutrient availability (e.g. Bruno et al, 2003; Garren et al., 2009)

It is difficult to decouple nutrient loading from other stressors, but eutrophication may well be increasing both the prevalence and severity of coral disease, as well as making corals more susceptible to coral bleaching. (adds to stress loads in coral reefs)

Question 13

HABs & toxins

As bloom events increasein frequency, harmful algal blooms are a range of genera and species that are toxic (can be fatal to humans).

Ci——— poisoning

Answer 13

Ciguatera poisoning

SE Asia and Pacific

Gambierdiscus toxicus

Suite of toxins: ciguatoxin, palytoxin, scaritoxin maitotoxin

Ingestion of top predator fish species

Symptoms: gastrointestinal (vomiting, diarrhoea) and neurological (e.g. headaches, hallucinations, ataxia, allodynia) can last years

Question 14

HABs & toxins

As bloom events increasein frequency, harmful algal blooms are a range of genera and species that are toxic (can be fatal to huma

S______ Poisoning

Answer 14

Saxitoxin

produced by Alexandrium, Gonyaulax and Pyrodinium spp.

selective sodium channel blocker ; interferes with nerve transmission, preventing normal cellular function and paralysis

‘Paralytic Shellfish Poisoning’ in humans

Question 15

HABs & toxins

As bloom events increasein frequency, harmful algal blooms are a range of genera and species that are toxic (can be fatal to humans)

B______ Poisoning

Answer 15

Brevetoxin

Karenia brevis (dinoflagellate)

Bind to voltage-gated sodium channels in nerve cells

Neurotoxic Shellfish Poisoning

nausea, vomiting, diarrhoea, parasthesia, cramps,

bronchoconstriction, paralysis, seizures, coma

Florida

Question 16

HABs & toxins

As bloom events increasein frequency, harmful algal blooms are a range of genera and species that are toxic (can be fatal to humans).

O______ Poisoning

Answer 16

Okadaic Acid

Blocks intestinal cellular de-phosphorylation; cells very permeable to water ; dehydration through diarrhoea and vomiting

‘Diarrhetic Shellfish Poisoning’

2000 serious harmful algal disease effects in humans are reported each year (15%). Incidences on the rise with greater eutrophication.

Question 17

Nuisance macro-algae

Answer 17

• Foul aquaculture cages, Blakey cover today mudflats
• Foul propellers
• Prevents birds feeding on mudflats

Question 18

Summary

Answer 18

• Increased biomass of phytoplankton and macrophyte vegetation
• Increased biomass of consumer species
• Shifts to bloom-forming algal species that might be toxic or inedible
• Increases in blooms of gelatinous zooplankton (marine environments)
• Increased biomass of benthic and epiphytic algae
• Changes in species composition of macrophyte vegetation
• Declines in coral reef health and loss of coral reef communities
• Increased incidence of fish kills
• Reductions in species diversity
• Reductions in harvestable fish and shellfish biomass
• Decreases in water transparency
• Taste, odour and drinking water treatment problems (freshwater systems)
• Oxygen depletion
• Decreases in perceived aesthetic value of the receiving waters

Question 19

Historical perspectives

Answer 19

JD Harrington invented the WC in 1500’s​ (Romans sophisticated flush toilet)

1730’s valve type toilets​

It was Albert Giblin who invented the flush-toilet in 1820

As people moved in to increasing larger conurbation so the traditional ‘stick it in the nearest body of water’ approach began to fail​

The Great Stink of 1858​; houses of parliament disbanded due to the stench of the Thames, prompted action to be taken

Our present sewerage system is a result of the great Victorian engineers: Joseph Bazalgette ​

Their response was the building of what at that time the most advanced system in the world​. It consisted of 6 main sewage collecting line which are about 100miles long, followed by another 450 miles.

Question 20

What do sewers have to deal with today?

Answer 20

55g of biosolids per person per day​

150 litres of wastewater used per person per day​

624,200 kilometres of sewers collect over 11 billion litres ​

Question 21

Urban Waste Water Treatment Directive (91/271/EEC)​

Answer 21

Urban Waste Water Treatment Directive (91/271/EEC)​

The Council Directive 91/271/EEC concerning urban waste-water treatment was adopted on 21 May 1991. Its objective is to protect the environment from the adverse effects of urban waste water discharges and discharges from certain industrial sectors (see Annex III of the Directive) and concerns the collection, treatment and discharge of:

Domestic waste water

Mixture of waste water

Waste water from certain industrial sectors

3 Types of sewage system;

surface-water drainage​

combined sewerage​

foul drainage

Foul water - Toilet, bath, shower, kitchen sink, washing machine, dishwasher, etc Local sewage treatment works

Surface water - Rainwater from roof, driveway, patio, roads, etc Local watercourse

Question 22

Whta are the stages of treatment?

Answer 22

1. Wastewater collection
2. Odour controll
3. Screening/preliminary
4. Primary treatment
5. Secondary treatment
6. Bio-solids handling
7. Tertiary treatment

Question 23

Describe wastewater collection treatment

Answer 23

Wastewater Collection

This is the first step in waste water treatment process. Collection systems are put in place by municipal administration, home owners as well as business owners to ensure that all the wastewater is collected and directed to a central point. This water is then directed to a treatment plant using underground drainage systems or by exhauster tracks owned and operated by business people. The transportation of wastewater should however be done under hygienic conditions. The pipes or tracks should be leak proof and the people offering the exhausting services should wear protective clothing.

Question 24

Describe odour controll treatment

Answer 24

Odor Control

At the treatment plant, odor control is very important. Wastewater contains a lot of dirty substances that cause a foul smell over time. To ensure that the surrounding areas are free of the foul smell, odor treatment processes are initiated at the treatment plant. All odor sources are contained and treated using chemicals to neutralize the foul smell producing elements. It is the first wastewater treatment plant process and it’s very important.

Question 25

Describe screening/preliminary treatment

Answer 25

3. Screening/preliminary

This is the next step in wastewater treatment process. Screening involves the removal of large objects for example nappies, cotton buds, plastics, diapers, rags, sanitary items, nappies, face wipes, broken bottles or bottle tops that in one way or another may damage the equipment. Failure to observe this step, results in constant machine and equipment problems. Specially designed equipment is used to get rid of grit that is usually washed down into the sewer lines by rainwater. The solid wastes removed from the wastewater are then transported and disposed of in landfills.

Question 26

Describe primary treatment

Answer 26

4. Primary Treatment

This process involves the separation of macrobiotic solid matter from the wastewater. Primary treatment is done by pouring the wastewater into big tanks for the solid matter to settle at the surface of the tanks. The sludge, the solid waste that settles at the surface of the tanks, is removed by large scrappers and is pushed to the center of the cylindrical tanks and later pumped out of the tanks for further treatment. The remaining water is then pumped for secondary treatment.

Question 27

Describe secondary treatment

Answer 27

5. Secondary Treatment

Also known as the activated sludge process, the secondary treatment stage involves adding seed sludge to the wastewater to ensure that is broken down further. Air is first pumped into huge aeration tanks which mix the wastewater with the seed sludge which is basically small amount of sludge, which fuels the growth of bacteria that uses oxygen and the growth of other small microorganisms that consume the remaining organic matter. This process leads to the production of large particles (aerated sludge) that settle down at the bottom of the huge tanks. The wastewater passes through the large tanks for a period of 3-6 hours.

High surface area will maximise bacterial growth and bacterial breakdown ​

Large tank with lots of material such as gravel ​

Question 28

Descrieb biosolids handling

Answer 28

6. Bio-solids handling

The solid matter that settle out after the primary and secondary treatment stages are directed to digesters. The digesters are heated at room temperature. The solid wastes are then treated for a month where they undergo anaerobic digestion. During this process, methane gases are produced and there is a formation of nutrient rich bio-solids which are recycled and dewatered into local firms. The methane gas formed is usually used as a source of energy at the treatment plants. It can be used to produce electricity in engines or to simply drive plant equipment. This gas can also be used in boilers to generate heat for digesters.

Question 29

Describe tertiary treatment

Answer 29

7. Tertiary treatment

Further treatment will depend where you are, and how sensitive/ pathogen rich / dangerous the the receiving waters are.

The tertiary treatment stage has the ability to remove up to 99 percent of the impurities from the wastewater. This produces effluent water that is close to drinking water quality. Unfortunately, this process tends to be a bit expensive as it requires special equipment, well trained and highly skilled equipment operators, chemicals and a steady energy supply. All these are not readily available. Chlorine and acids – concerns about bi products and risk to human health​.

to address different pollutants using different treatment processes​

sand filters or sedimentation ponds; ​

reed beds for nitrates; electrolysis for phosphates​

disinfection: e.g. chlorine, peracetic acid, ozone, UV​

biological membrane filters

Question 30

What is disinfection?

Answer 30

8. Disinfection

After the primary treatment stage and the secondary treatment process, there are still some diseases causing organisms in the remaining treated wastewater. To eliminate them, the wastewater must be disinfected for at least 20-25 minutes in tanks that contain a mixture of chlorine and sodium hypochlorite. The disinfection process is an integral part of the treatment process because it guards the health of the animals and the local people who use the water for other purposes. The effluent (treated waste water) is later released into the environment through the local water ways.

Question 31

How is the level of treatment descided?

Answer 31

What level of treatment?​

• Depends on ‘p.e.’ = population equivalent. ​
  
  • Refers to the organic biodegradable load having a 5 day BOD of 60g of oxygen per day​
  • Proxy for organic matter load estimates​
  • 2ndary treatment required for inland waters 2000 p.e. or coastal waters above 10,000 p.e.​
• Waters deemed to be ‘sensitive’ require tertiary treatment​
  
  • Eutrophic or could become so in the near future without tertiary protection;​
  • Abstraction sources that have or could have high nitrate levels without tertiary protection;​
  • Other directives’ water in need of or already receiving tertiary protection.
• Pe includes effulgent loading which can be increased by industry ​
• EU legislation – secondary treatment required for .. ​
• Where used for abstraction – water is taken from rivers to be potable or agriculture

Question 32

How is sludge treated?

Answer 32

The sludge that is produced and collected during the primary and secondary treatment processes requires concentration and thickening to enable further processing. It is put into thickening tanks that allow it to settle down and later separates from the water. This process can take up to 24 hours. The remaining water is collected and sent back to the huge aeration tanks for further treatment. The sludge is then treated and sent back into the environment and can be used for agricultural use.

Question 33

Describe anarobic digestion for sludge treatment.

Answer 33

Anaerobic digestion ​

• at 35oC ; 15-20d ; CH4 and CO2 produced
• Aerobic digestion, air pumped through​
• Dewatering via gravity or thickening agents
• Lime stabilisation​
• Thermal drying
• • 1 or a combination of the steps used ​
• Lime is good if it used on crops

Question 34

Describe the disposal of sludge

Answer 34

• Disposal of sludge options
• Disposal of biosolids to farm​
  
  • Valuable source of nutrients​
  • Best Practicable Environmental Option​
  • about 60- 80% of treated biosolid sludge is disposed of in this way in the UK​. 30 - 40% globally)
  • Only certain sources of sludge because of risks of pathogens and chemical residues: Safe Sludge Matrix​ - what crops can have and can’t have slurry
• Incineration ~18%​ or used as a fuel in dried sludge bricks
• Recycling to brownfield sites ~10%​, adding treated sludge can make them more environmentally suitable in many years to come.
• Disposal in landfill​
• Recycled building material (dried and made into building blocks, materials)

​Recently invested in the UK sewage systems which have remained largely untouched since the Victorian times.

• Sewer effects on a rocky shore
• Luxuriant algae
• SRD
• Staining and anoxia
• Sewage is mainly FW!

Question 35

How does th edisposal of sludge increase the burden on an overflow system?

Answer 35

Increasing burden on ‘overflow’ system​

• Increasing trend for decking and paving​ - run-off
• Climate change and more frequent flooding​, shock loading sewage systems
• In coastal areas there is a vast seasonal increase in the population​, Tourist destinations can double in size.
• Holiday- makers can easily double the effective population size​. More of a prblem in developing countries
• Doubling the quantity of sewage that needs to be disposed of, at a time when rivers are having the least flows for dilution

Question 36

Monitoring Environment under EU Directives

What are a core set of indicators?

Answer 36

“Core set of Indicators”​

• Agriculture​
• Air​
• Biodiversity​
• Climate change
• Energy​
• Fisheries​
• Terrestrial​
• Transport​
• Waste ​
• Water​
  
  • Bathing water quality​
  • Chlorophyll a​
  • Nutrients in freshwater​
  • Nutrients in coastal and marine waters ​
  • Oxygen consumption in rivers
  • Urban waste treatment​
  • Use of freshwater resources

Question 37

What does the Bathing waters directive require?|

Answer 37

• EC Bathing Waters Directive 1976 requires all traditional bathing waters to be designated​Revised Bathing Water Directive (2006/7/EC)​
• The UK has beaches officially designated as bathing beaches. ​
• Each of these is required, under EC law to meet certain bacteriological, aesthetic and other physical-chemical water quality parameters. ​
  
  • two bacteria: Escherichia coli and intestinal enterococci​
  • taking of a pre-season sample (taken shortly before the start of the bathing season) ​a minimum of four samples per season​
  • a minimum of one sample per month​
  • Up to relatively recently, only 76% of UK bathing beaches meet the bacteriological criteria. ​
  • But see 2014 report
• The revisions in 2006 received criticism due to being considered to be oversimplified. Only monitoring two bacteria, gives way for loop-holes.

Question 38

Shellfish water sdirective

Answer 38

Shellfish waters

The EC Shellfish Waters directive lays down standards for water in areas where shellfish are raised for human consumption, include limits on chemical contaminants and bacteria.

Question 39

Water frameworjk directive

Answer 39

Water Framework Directive

Requires all inland and coastal water bodies to reach at least “good status” by 2015.

Overarching and unifying piece of EU legislation

Marine scientists should appreciate the implications of river basins management

Water framework directive is implemented by a series of partnerships

Question 40

Marine strategy framework directive

Answer 40

Marine Strategy Framework Directive

• Based on an “Ecosystem Approach”
• “a resource planning and management approach that integrates the connections between land air water, all living things, human beings their activities and institutions” (Farmer et al., 2012)
• the approach recognises the total dependence of human activity on the ecosystems in which they take place
• the aim of “maintaining biodiversity and providing diverse and dynamic oceans and seas which are clean healthy and productive”.
• to achieve Good Environmental Status (GEnS) within member states’ Exclusive Economic Zones (EEZs) on a regional seas basis by 2020.
• A lot more complex – huge challenge of trying to rationalise and bring together different countries which will be managing a water system together
• 11 main environmental indicators, 1 category for eutrophication.

Question 41

Jane Paper

Conley et al., 2007. Ecological Applications 17, S165-S184

Answer 41

See (Potts et al., 2015) Problems associated with implementation of MSFD

Ecological ‘choke’ points in Baltic: redn of fertilizer use not resulting in immediate reduction of nutrient emissions and delays in ecosystem response.

The time from changes in pressures to changes in state can take decades.

UK has got sewage system in gear, working hard to reduce its inputs of untreated sewage

Restrictions on how close cattle can be to water (drinking and trampling)

Paper in summary

Complex, on the whole with better legislation we are managing our use of agricultural fertilisers better

However, the worst extreme year was in 2002 - a hickup as a result of complex weather pattern

Another useful paper to look at is potts et Al.

Looks at how it is inherently very complex

Certain choke points – which are problematic areas institutional.or

Example they give is eutopucatiib in the Baltic

Sources fertilisers use

Whos going to incur cist = farmers

Choke point – several decades for the benefits to be seen

The farmers are not going to benefit from clearer waters, tourism or fish stocks and incur the cost of reduced fertilisers.

The farmers start lobbying for reduced standards

On the flip side other people Libby for stricter controlled as no immediate benefits

Concludes it is one of the challenges for imputing a complex bit of legislation

Question 42

Summary

Answer 42

Summary

Agriculture, industrial and domestic sewage effluent (diffuse and point source) input organic and nutrient loadings to coastal environments​

There are a range of European level directives are serving to address impacts of organic and associated waste inputs to coastal waters​

While improvements have been made in our (UK) track record on sewage treatment, and associated human health implications of sewage discharge to bathing waters, North Sea, European and global incidences of nutrient loading give cause for concern for ecological functioning​

Increasing number of areas worldwide experiencing symptoms of eutrophication stresses the global scale of the problem ​

65% of Europe’s Atlantic coast displays signs of eutrophication. ​

Models suggest that the coastal waters of the North Sea may be more sensitive to anthropogenic rivers loads than climate change in the near future (to 2040) (see Picart et al 2015)

Question 43

WIDER READING: dead zones

Answer 43

• Diaz, R.J. & Rosenberg, R. (2008). Spreading dead zones and consequences for marine ecosystems. Science, Vol 321 no. 5891 pp. 926-929
  
  • Dead zones in coastal oceans have spread exponentially since the 1960s.
  • The formation of dead zones has been exacerbated by the increase in primary production and consequent worldwide coastal eutrophication fueled by riverine runoff of fertilizers and the burning of fossil fuels.
  • Dead zones have now been reported from more than 400 systems, affecting a total area of more than 245,000 square kilometers.

Question 44

WIDER READING: benthic responses to enrichment

Answer 44

• Rees et al., 2006. Benthic responses to organic enrichment and climatic events in the western North Sea. J. Mar. Biol. Ass. UK, 86, 1-18.
  
  • In the UK, the disposal of waste at sea from ships is controlled under the food and environment protection act (1985).
  • Sewage disposal from the Tyne commenced in 1978, with aggregation of 500,000 DWT.

Question 45

WIDER READING Hypoxia - long term

Answer 45

• Conley et al., 2007. Ecological Applications 17, S165-S184 – Long term changes and impacts of hypoxia in Danish coastal waters.
  
  • Mean average bottom-water oxygen concentration during summer have significantly declined in coastal marine ecosystems.
  • The most severe and widespread hypoxic event that has occurred in Danish open waters occurred in late summer and autumn 2002. The event resulted from a combination of unusually high precipitation during winter, which washed nitrogen into the sea, and unusually calm and warm weather in late summer and autumn, limiting the supply of oxygen to the bottom water – in 2002 >9000km2 (21% of the total bottom area) was exposed to oxygen conc. <2mg/L for up to 20 weeks.

Question 46

WIDER READING: eutrophic indicators

Answer 46

• Ferreira JG, et al (2011) Overview of eutrophication indicators to assess environmental status within the european marine strategy framework directive. Estuar Coast Shelf Sci 93:117–131
  
  • European Marine Strategy Framework Directive – MSFD
  • This paper presents a review of work carried out by the eutrophication task group, and reports the main findings to the scientific community.
  • Chlorophyll a used widely as an indicator for phytoplankton biomass and therefore as an indicator of eutrophication levels.
  • Eutrophication is a process not a state.