Water, its Pollution and Abatement Technological Strategies: Application of Cheap and Environmentally Friendly Local Resources

Description

Increased domestic, industrial and agricultural practices have led to a rise in wastewater discharges, hence water pollution. Public awareness of water pollution events together with the effluent discharge standards now set; have led producers to devise various ways of treating these effluents before discharge. Such ways should, however, be environmentally friendly and cost effective. One such approach to wastewater treatment is the application of natural products particularly algae, which have been found to be good adsorbents for certain contaminants. Biosorption of the heavy metal ions, Cd²⁺, Cu²⁺, Pb²⁺ and Zn²⁺ by the brown algae, ascophyllum nodosum and moringa oleifera has been studied by measuring the efficiency of their removal from ‘waters’ using contact time and pH as the variables in a batch-process series of experiments. Biosorption of mixtures of the metal ions to study their competitive effects within the algae at pH’s of 5 and 9 and moringa o. at pH 4 has also been done. The concentration of metal ions adsorbed were measured using inductively coupled plasma-optical emission spectrometer. Flow injection experiment was done by incorporating a column packed with the algae to determine its maximum capacity for metal biosorption. The effects of stirring on metal biosorption and particle size distribution of three pore size categories of the algae using the mastersizer equipment were also investigated. Dry moringa o. were de-shelled by hand and crushed by paste and mortar, washed and dried. Forty grams of powder were then shaken with 400 mL of acetone /ethanol mixture for 30 minutes, centrifuged and dried in the oven at 30 ⁰C overnight. The results for algae show that for the single systems, Cd²⁺ were the most efficiently biosorbed metal ions while Pb²⁺ were the least; following the order Cd²⁺>> Zn²⁺ ≥Cu²⁺> Pb²⁺ and Cd²⁺>Zn²⁺>Pb²⁺>Cu²⁺ at pH’s 5 and 9, respectively for mixed ions for algae of pore size < 1 mm. Reduction in algae size lowered metal biosorption and also changed the order to Zn²⁺>Cd²⁺>Cu²⁺>Pb²⁺. A pH of 5 was found to be optimum for adsorption of these metal ions. The metal uptake increased with contact time based on a solid-to-liquid ratio (mass of algae to volume of water) of 1:100. The algal biomass demonstrated a Langmuir adsorption-like isotherm, with a steep rise in the initial slope of the kinetics prior to an equilibrium-like asymptote and stirring was found to lower the time to attain equilibrium. Maximum % biosorption could only be attained after 1 hour of contact. Modified algae facilitated by treatment using KMnO₄ and Na₂CO₃ enhanced heavy metal biosorption with the former offering better properties. The untreated algae were, however, found to have a maximum capacity for metal biosorption of more than 4 hours. From particle size distribution, although the majority of algae particles in each category were of the largest size, their % volume occupied was low. For moringa o. single systems, the larger fraction (< 1 mm) offered better biosorption abilities than the smaller one (> 500 µm) for Cd and Zn. Generally, the smaller particle size fraction (< 500 µm) was least in biosorbing metals and the order of biosorption for all particle sizes was Zn > Cu > Cd > Pb. Although treatment improved moringa’s biosorption abilities, KMnO₄ proved a better enhancer of metal biosorption than Na₂CO₃. At low pH, the trend of biosorption for moringa o. was Zn > Cu >Cd > Pb while at high pH Cd was the most with Pb the least and the order was Cd ≥ Zn > Cu >Pb. Both algae and moringa adsorption followed Langmuir model which proceeds through surface and mono layer mechanism than the Freundlich which is hetero based. It was also found that all metals except Zn with algae adsorbent adopted pseudo second order reaction.

John Lusweti Kituyi was born on 15^th March, 1956 in Ndivisi Village, Ndivisi Location, Bungoma County; the last-born child of the late Mzee Obed Kitui Lusweti (commonly called Walucho) and Mama Rabecca Makokha (Mayi Achupa). He started schooling shortly after Kenya attained independence in 1964 at Ndivisi Primary School and continued until 1971 when he sat for C.P.E. In 1972 he joined Butula Secondary for a four-year secondary education and performed very well in E.A.C.E. He then enrolled for A’ levels at St. Pauls Amukura High School in 1976 and later on proceeded to the University of Nairobi for a Bachelor of Education degree from 1978-1981.

Upon completion, he was posted to his former high school, St. Paul’s Amukura to teach Chemistry and Mathematics. Two years later, he was transferred to St. Peter’s Mumias Boys until 1984 when he left for a master’s degree at Kenyatta University. In 1986 he was posted to Moi Science Teachers’ College, the present University of Eldoret, until 1990 when he joined Moi University as a Tutorial Fellow in the Department of Chemistry and promoted to Lecturer in 1992.

He graduated with a Doctor of Philosophy (PhD) in Physical Chemistry, Moi University in 2001. The PhD Thesis was entitled “Investigation of Heavy Metal Speciation in Lake Nakuru”. Eight (8) years later, he rose to Senior Lecturer scale and soon after, secured a Commonwealth Fellowship at the University of Plymouth, UK in the same year for a period of six (6) months. He became an Associate Professor in 2012, a position he held for six (6) years before attaining the current position of Professor of Physical Chemistry in 2018.

Professor Kituyi’s research area leans towards applied chemistry; water pollution and use of natural products and synthesised complexes in bioremediation of environmental matrices.

Professionally, he has a wealth of experience and an incomparable many years’ record of postgraduate supervision. He has so far published more than 60 articles in referred journals, 2 book chapters and supervised to graduation 8 PhD and 30 MSc students. He has also examined 4 internal and 3 external PhD theses, 24 internal and 12 external MSc theses. He is an external examiner for two public universities in Kenya.

He has been a head of department, a warden, chairman, board of management of a number of schools and is actively involved in church leadership.

Professor John Lusweti Kituyi is married to Pamela Rebecca Musikhe and they are blessed with children; Faith and Dan, Dr. Victor and Dr. Winny, Mercy and Pr. James, Eng. Timothy and David. He has grandchildren Shirley, Giovanni, Elianna, Ethan, Elon, Jehiel, Jemiel, Jeriel and Jediel.