The study investigated the potential of water hyacinths and phytoplankton scum, an aquatic weed, as binder for production of fuel briquettes. It also evaluated some physical and combustion characteristics. The water hyacinths were manually harvested, cleaned, sun-dried, and milled to particle sizes distribution ranging from <0.25 to 4.75 mm using hammer mill. The water hyacinth grinds and binder (phytoplankton scum) at 10% (B 1 ), 20% (B 2 ), 30% (B 3 ), 40% (B 4 ), and 50% (B 5 ) by weight of each feedstock were fed into a steel cylindrical die of dimension 14.3 cm height and 4.7 cm diameter and compressed by hydraulic press at pressure 20 MPa with dwell time of 45 seconds. Data were analysed using analysis of variance and descriptive statistics. Initial bulk density of uncompressed mixture of water hyacinth and phytoplankton scum at different binder levels varied between 113.86 ± 3.75 (B 1 ) and 156.93 ± 4.82 kg/m 3 (B 5 ). Compressed and relaxed densities of water hyacinth briquettes at different binder proportions showed significant difference < 0.05. Durability of the briquettes improved with increased binder proportion. Phytoplankton scum improved the mechanical handling characteristics of the briquettes. It could be concluded that production of water hyacinth briquettes is feasible, cheaper, and environmentally friendly and that they compete favourably with other agricultural products.

Okpoka Creek of the Upper Bonny Estuary in the Niger Delta is a tidal creek receiving organic anthropogenic effluents from its environs. The study investigated the influence of tides (low and high) on the species composition, diversity, abundance, and distribution of phytoplankton. The surface water and phytoplankton samples were collected monthly from May 2004 to April 2006 at both tides from ten stations according to standard methods. Phytoplankton was identified microscopically. Species diversity was calculated using standard indices. Data analyses were done using analysis of variance, Duncan multiple range, and descriptive statistics. Phosphate and ammonia exceeded international acceptable levels of 0.10 mg/L for natural water bodies indicating high nutrient status, organic matter, and potential pollutants. A total of 158 species of phytoplankton were identified. Diatoms dominated the phytoplankton (62.9%). Diversity indices of diatoms were1.5±0.03(Margalef) and0.8±0.01(Shannon). Pollution-indicator species such asNavicula microcephala,Nitzschia sigma,Synedra ulna(diatoms),Cladophora glomerata(green alga),Euglena acus(euglenoid),Anabeana spiroides(blue-green alga), andCeratium furca(dinoflagellate) were recorded at either only low, high or both tides. Concerted environmental surveillance on Upper Bonny Estuary is advocated to reduce the inflow of pollutants from the Bonny Estuary into this Creek caused by tidal influence.

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The knowledge of water resistance capacity of briquettes is important in order to determine how sensitive the produced briquettes are to moisture change during storage. The relative changes in length and diameter of briquettes during immersion in water for 6 hours were investigated. This was conducted to determine hygroscopic property of produced briquettes under process variables levels of binder (10, 20, 30, 40, and 50%) by weight of residue, compaction pressure (3.0, 5.0, 7.0, and 9.0 MPa) and particle size (0.5, 1.6, and 4 mm of dried and ground water hyacinth). Data was statistically analysed using Analysis of Variance, the Duncan Multiple Range Test, and descriptive statistics. The relative change in length of briquettes with process variables ranged significantly from 7.21 ± 0.24% to 15.62 ± 3.07% (binder), 8.58 ± 0.55% to 13.97 ± 2.50% (compaction pressure), and 6.15 ± 0.21% to 17.78 ± 1.26% (particle size) ( < 0.05). Furthermore, the relative change in diameter of briquettes with binder, compaction pressure, and particle size varied significantly from 2.77 ± 0.13% to 3.02 ± 0.12%, 2.58 ± 0.12% to 3.31 ± 0.11%, and 2.64 ± 0.14% to 3.17 ± 0.06%, respectively ( < 0.05). This study suggests optimum process variables required to produce briquettes of high water resistance capacity for humid environments like the Niger Delta, Nigeria, as 50% (binder proportion), 9 MPa (compaction pressure), and 0.5 mm (particle size).