The Industrial Waste Management

Introduction

Nigeria with its population of 182,091,542,140 million (2007 release) is urbanizing at an astonishing pace with increasing industrialization, Over 5000 process industries are concentrated in major urban centers such as Lagos, Sango-Ota, Port Harcourt, Ibadan, Aba, Kaduna, and Kano to name a few. These industries vary from textile plants, breweries, slaughterhouses, refineries, pulp and paper, tarpaulin, rubber and plastics. Nigeria’s urban population increased from 20 per cent in 1970 to about 38 per cent in 1993. There are over 40 million people now living in cities and the urban population is increasing at 5.5 per cent per annum. It was observed that almost every industry dumps its waste on the backyard without concern for the environment around. Some of these wastes along with their leachates are seen mixed with hazardous wastes and joining streams and rivers through a network of open drains. This environmental degradation is felt in every walk of life. Though a large volume of literature is available on the quality of wastes generated and their dispersion into the environment, very little information is available on the quantity of wastes, their fate and the management practices in Nigeria. Most of the industries dispose their wastes without any treatment only to be removed and dumped elsewhere. There has been an environmental policy on ground but the implementation strategy is weak or ineffective in most of the States. This paper examines the broad groups of industries, the nature of wastes (both liquid and solid) generated by them and the technological options for effective management.

Industrial wastes

Industrial wastes may be grouped into 2 broad categories: Process wastes and chemical wastes. The process wastes depend on the nature of the industry, the raw materials processed and nature of the process itself. Some of the manufacturing methods that generate such wastes are:
• sedimentation,
• flocculation,
• washing,
• filtering,
• evaporation,
• distillation,
• electrolysis,
• absorption,
• crystallization,
• screening,
• burning, and
• centrifuging,
to name a few. These wastes cause pollution of water, soil, and air depending on the nature of the pollutant, the concentration and the magnitude of the discharge (Box 1). The industrial wastes may be solid, liquid or gaseous. Some may be thermal in nature.

The common pollution problems threatening the environment include oxygen depletion of water bodies, fish kills emission of noxious gases and change in flora and fauna leading to biodiversity loss. In water they contribute to high pollution load, colour changes, turbidity, odour, heat, particulate matter, dissolved solids, BOD, COD, various inorganic elements, volatile organic compounds, toxic chemicals and others.

Similarly, the solid wastes and their leachates entering the water and food chains may effect the environment and health. At the moment, a majority of the industries either treat their wastes minimally or do not treat at all. There is no segregation of wastes and as a result hazardous and non-hazardous, and infectious mix together and go in the waste stream.

Some of the major industries and their waste characteristics are given in Box 2. The options for industrial waste disposal are to discharge into surface waters, coastal waters, land and sewers, if available. Depending on where they are disposed, the effluent quality has to be maintained. The flow rates, weather conditions, the characteristics of the receiving body, and the waste characteristics over a time scale are required before planning a treatment technology.

Developments in waste water management

There is a need to treat industrial wastes whether they are hazardous or not as they contain pollutants above the national specified limits. Hazardous components have to be detoxified and others have to be brought back into the cycle of life. Several developments have taken place during the last century to manage the wastes.

In the earlier days it was thought that “solution to pollution is dilution” and this approach never yielded any positive result. The chemical coagulation using lime, ferric salts and alum did not yield any significant results and on the other hand the rivers have deteriorated to a great extent due to the dissolved impurities which can escape the chemical methods.

The available technologies for treating liquid wastes are:
• Primary treatment: Sedimentation tanks, pH control, Floatation, etc.;
• Secondary treatment: Trickling or percolating filters, Activated sludge process, Oxidation pond, Oxidation ditches, Root Zone Technology, Sludge digestion, Aerobic and anaerobic lagoon;
• Tertiary treatment: Physico-chemical methods, filtration using granular activated carbon, diatomaceous earth etc., reverse osmosis, membrane filtration, Phyto-techniques,
Balancing of various streams and pretreatment are essential before sending for secondary / biological treatment.

In the wastewater treatment, the technology option depends on the goal. One should find out which element or substance is to be reduced or eliminated from the effluents. BOD, SS, Volatile organics, some specific chemicals such as P, N, S, or heavy metals or toxic chemicals have to be addressed. On certain situations adsorbents such as activated charcoal, clays (kaolin or bentonite) may be very useful particularly for colour, heavy metals and volatile organics.

Solid wastes and their management

Indiscriminate disposal of solid wastes (including the hazardous or infectious wastes) which is the normal practice in many urban centres, causes damage to the environment and affect health of the communities. Environmental damage may occur in the form of ecological disturbances such as:
- Blockage of drains and stream flows resulting in flood disasters
- Fire hazards when the wastes are dry
- Obnoxious smell, gaseous and smoke emissions
- Breeding site for rats, flies and other vectors of public health importance
- Harbours and act as reservoir of infectious agents
- Offers a venue for stray animals, destitutes, and lunatics
- Eutrophication of water bodies,
- Death of useful flora and fauna of aquatic or terrestrial systems
- Biodiversity loss
- Morbidity or mortality of populations due to injuries and infections

The solid wastes, particularly the municipal solid wastes, crop residues from agro-based industries, and livestock dung are rich in organic matter and other essential nutrients such as nitrogen, phosphorus and potassium and micronutrients. They are highly putrescible and favour breeding of flies, and harbour pathogens that cause tetanus, Clostridium that produces toxins in foods, and other infectious agents which may enter water, soil and food.

The leachates are particular concern a they may be toxic and high in BOD and COD, particulate matter and dissolved matter. Hey may also promote mosquito breeding when stagnant or contaminate ground water and land. The solid wastes in developing countries are normally mixed with other wastes from human and developmental activities, such as metals, glass, plastics and a host of human utilities. Some of these have great potential for recycling if properly segregated, collected and utilized.

In waste management practice, various steps are involved. Collection, storage, transportation and hygienic disposal are the major phases of waste management. Most often we fail at the proper collection stage. There is need for appropriate tools and equipment for all the stages involved. Wherever possible, one should think of using appropriate materials, tools and technology. As much as possible, one should aim at waste minimization, reuse, and recycling before dumping the wastes into a dustbin. Recycling the non-biodegradables will help the environment, individual and the local industry which needs cheaper raw material for pruduction. If this has to be successful, separation should start at source. There are many industries that recycle these materials. The Shaki Township has metal recyclers, numbering over 3000. There are over 100 plastic recyclers in Lagos, in Ibadan and practically every city in Nigeria. There is money in it both for the householder, the picker and even the industry, which gains through the use of recycled raw materials.

For final disposal, some of the accepted methods include:
• sanitary landfill,
• composting,
• incineration
• fixing in inert materials such as glass and buried under deep soils or abandoned mines (e.g. toxic and radioactive wastes);

Various Governments have in recent years banned the practice of sea disposal, as the seas all around are grossly polluted resulting in the kill of fish, whales and other animals. The ultimate objective of waste treatment is to fully oxidize the basic elements (Carbon, Nitrogen, Phosphorus, and Sulphur) so that they will not deteriorate the water, soil or air around us. It is wiser to recycle the organic wastes to benefit the barren agricultural land, which is vast in the country. Organic fertilizer / manure or compost is very helpful even in controlling desertification as it can promote greening the deserts. The Pace Setter Fertilizer plant at Bodija market in Ibadan has received the attention of various people and establishments all over the world. Recently the UN and Dubai Municipality have awarded the “Best Practice Award” to this venture. Organic manure has helped Denmark in reviving the contaminated land in a fishing village where an industry polluted groundwater and soil with mercury arising from a pesticide industry. Integrated waste management is economical and viable. In Nigeria today, there are 7 waste recycling plants developed by us for waste recycling.

One of the best methods of industrial waste management is found in Denmark at ‘Komunikemi’. Here the Government provided the facility and the industries send their hazardous wastes and pay for the treatment or disposal. Incineration, landfill and composting activities are put at a common place in an integrated manner. Private sector brings the wastes and pay for the facility services. Appropriate technology is used depending on the nature of waste. Payment of fee depends on the nature and quantity of the waste being processed. Certain emerging wastes such as radioactive and electronic wastes (e-wastes) have to be treated in a different way and some level of pretreatment / special treatment is required. Nigeria has also brought out Healthcare waste management policy. There are colour codes and specifications for various phases of waste handling and management.

Conclusions and Recommendations

Hitherto, in Nigeria the emphasis in waste management has been limited to assessment including EIA, EAR and Risk assessment. Proper handling practices and treatment are not practiced in many industries in the country. The regulatory bodies on the other hand have been very sympathetic and have been giving ‘holiday’ for not implementing any treatment facilities. Almost after 13 years of its creation, FEPA (Ministry of Environment where appropriate) have to go into action on enforcing effective treatment and adhering to the stipulated standards.
• There is need to strengthen Federal, State and selective private laboratories to cope with the needs and demand of waste characterization;
• At the moment many unqualified ‘touts’ have entered into the field as ‘Environmental Consultants’; there is need to screen and weed them out;
• Quality assurance, Quality control, inter-laboratory standardization and periodic training and retraining of all ‘Environmental Practitioners’ should be made mandatory;
• Environment is multidisciplinary and in tackling the problems, a team effort is more beneficial; where necessary other disciplines should join hands in solving the problems;
• A National ‘Green Peace’ Group should be formed and encouraged to monitor the industries, communities and regulatory bodies in keeping the environment clean and habitable; and
• There is need to take stock of the availability of technologies and the expertise within the country through proper screening and draft them to address the environmental challenges.


Pollution of water bodies due to solid wastes – an environmental threa