Studies On The Treatment Of Coal And Brewery Wastewater Using Adsorption And Coagulation– Flocculation Techniques

2.3 SOLID COMPOSITION IN WASTE WATER EFFLUENT

Solids are present in water in three main forms:

a) Suspended particles
b) Colloids
c) Dissolved molecules:

a). Suspended particles: These consist of sand, vegetable matter and silts. The ranges in size vary from very large particles down to particles with a typical dimension of 10 μm. Wastewater and industrial effluent treatment require removal of suspended solids for purification and possible re-usage (Brostow et al, 2009). The removal can be accomplished by gravitation (very slow), by coagulation dependent on electric charge situation) and by flocculation (not dependent on electric charges and the fastest). In organic flocculants are used in very large quantities, they leave large amounts of sludge and are strongly affected by pH charges (Brostow et al, 2009).

b) Colloids: These are very fine particles typically ranging from 10nm to 10 μm. The colloids (means glue- like) are usually charged and this charge is frequently responsible for their stability (Anderson, 1979). These colloids may includes xxviii organic and inorganic particulates. The most frequently occurring forces between colloids are van der Waalls forces, electrostatic forces and forces due to adsorbed macromolecule (Terlizzi, 1994; Ma et al, 2001). Generally, we have hydrophilic colloids (e.g. soap) and hydrophobic colloids (e.g. clay, non-hydrated metal oxides). When these colloids are mixed with water, they form stable colloidal solutions with similar negative charges that keep the particles separate (Binnie et al, 2002).

c). Dissolved Molecules: Dissolved Molecules are present as individual molecules or as ions. Dissolved molecules can not be removed by conventional physical treatment like sedimentation and filtration.

2.4 PUMPKIN SEEDS (PEPITA, CUCURBITA PEPO)

A Pepita (From Mexican Spanish: pepita de calabaza, “little seed of squash”) or pumpkin seed is an edible seed of a pumpkin or other cultivar of squash (genus cucurbita), typically rather flat and asymmetrically oval, and light green in colour inside a white hull. The word can refer either to the hulled cernel or unhulled whole seed, and most commonly refers to the roasted end product. The pressed oil of the roasted seeds of a specific pumpkin variety is also used in Central and Eastern European cuisine. Pumpkin seeds have medicinal properties. They are used to cure catarrh, demulcent, diuretic, anthelminitic, lower cholesterol and heal arthritis. In 2007, Stevenson et al of the USDA’s New crops products Research unit searched the primary literature for information about the lipid content of pepitas from seven cultivars of C. Maxima. They found the following ranges of fatty acid content in C. maxima pepitas:

The reported concentration of myristate and palmitate (the cholestrogenic fatty acids) for the pepitas ranged from 1.6% to 4.9% (Stevenson et al, 2007). The total unsaturated fatty acid concentration ranged from 9% to 21% of the pepita (Stevenson et al, 2007). The total fat content ranged from 11% to 52% of the pepita. Based on the quantity of alphatocopherol extracted in the oil, the vitamin E content of the twelve C. maxima cultivar seeds ranged from the seeds of pumpkins, such as cucurbita pepo varieties have been subjected to a great deal of research especially into the treatment of prostate ailments to 19mg/g of pepita (Stevenson et al, 2007).

2.5 MUCUNA PRURIENS

Mucuna pruriens is a creeping legume which offers good mulch and soil over (Asongwed-Awa, 2002).

2.5.1 HISTORY Velvetbean, a vigorous annual climbing legume, originally came from southern China and Eastern India, where it was at one time widely; cultivated as a green vegetable crop (CSIR, 1962;Burkill,1966;Duke,1981; Wilmot-Dear,1984). The genus Mucuna (Adans), belonging to the Fabaceae family, covers perhaps 100 species of annual and perennial legumes including the annual velvet bean (Lorenzetti et al, 2010). The genus stizolobium was used by Bort (1909) to distinguish velvetbean from perennial Mucuna spp, but this distinction was not maintained by Burkill (1966) or Bailey (1947). Synonyms Mucuna utilis wall.

2.5.2 COMMON NAMES

Velvet bean, banana stock pea (Aust.), Ojo de venado, Poroto atercipelado (Arg.), Frijol terciopela (Mex.), haba de terciopelo (P.R) Pois a grater, haricot veloute, pois mascate, dolique de Floride, alkusi, makhmali sem, alkushi, cigu, kaocho, taingilotra, stizolobia, fluweelbootjie, nescafe, buffalo bean (Bachmann, 2000).

2.5.3 DESCRIPTION

Velvet beans are annual, or perennial, herbaceous, vigorous climbing vines, which can reach 18m in length when grown on supports and even on the ground could attain a length of 5.5m but 2-3m is normal, although bushy forms also exist (Bachmann, 2000).

a). Roots: The roots are fleshy usually well nodulated and produced near the soil surface (Bachmann, 2000). They are also bitter, sweet thermogenic emollient stimulant, purgative, aphrodisiac and diueretic (Salau, A. and Odeleye, O.M., 2007).
b). Stems: The long trailing stems are rather slender and sparsely pubescent (Bachman, 2000).
c). Leaves: The stems bear numerous alternate, trifoliolate leaves on short, hairy, fleshy petioles, with large, ovate leaflets, they are glabrous and leaflets, they are about 10cm long x 8cm wide (Bachmann, 2000). The leaves are also aphrodisiac (Salau, A and Odeleye, O.M., 2007). d).Seeds: The pods contain 4-6 seeds, globular, approximately 1.2 x 1.2cm, often mottled brown or black colour, sometimes with a pale-grey background, a few cultivars surrounded by a distinctive white aril (Bachmann, 2000). The seed coat is hard, thick and glossy. One hundred seeds weigh approximately 109g (Bachmann, 2000). The seeds are a stringent, laxative, anthelmentic, alexipharmic and tonic (Taylor, 2005). A clinical study confirmed the efficacy of the seeds in the management of parkinson’s disease by virtue of their L-DOPA content (Manyam et al, 1995; Bell et al, 1995; Bell et al, 1971).
e). Flowers: The inflorescence is axillary and flowers, usually 5-30, are showy, and purple red or greenish yellow in colour (Bachmann, 2000). Flowering may be stimulated by cooler night temperature (21oC) (Duke, 1981). f) Fruit: Pods are 9-14cm long, hard, curved, slightly ridged and covered with soft black, white or grey hairs which give them a velvety appearance (Bachmann, 2000).

2.5.4 HABITAT

They are now cultivated in many tropical and subtropical areas, and through breeding, certain cultivars tolerant of more temperate conditions have been developed (Bachman, 2000).

2.5.5 VARIABILITY

There are numerous cultivars of M. Pruriens, some of which were formerly treated as separate species. The principal ones (Bachmann, 2000) are:
i). Deering, Florida or Georgia velvet bean, frequently designated as stizaolobiun deeringianum or Mucuna deeringiana, grown in the USA.
ii). Bengal velvet bean, often designated as M. utile or S. utile in India.
iii). Mauritus velvet bean, often designated as M. aterrima or S. aterimum, grown in Mauritus, Brazil, Australia and the W.I
iv) Yokohama velvet bean, usually designated as S. hassjoo originated in Japan.
V). Lyon bean, designated M. nivea, S. Niveum, M Coclinchinnensis or carpogon grown in Philippines and SE. Asia.